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Background: Triatoma brasiliensis, a triatomine-bug vector of Chagas disease, evolved in the semiarid Caatinga, where it occupies rocky outcrops, shrubby cacti, and human dwellings. Dwellings and rocks are considered high-quality microhabitats for this saxicolous species, whereas cacti probably represent secondary, lower-quality microhabitats. This 'microhabitat-quality hierarchy' hypothesis predicts that T. brasiliensis populations occupying dwellings or rocks should endure harsh environmental conditions better than their cactus-living relatives. Methods/Findings: We tested this prediction by comparing T. brasiliensis infestation (proportion of microhabitats with bugs), density (bugs per microhabitat), and crowding (bugs per infested microhabitat) in dwellings, rocks, and cacti sampled before and during the extreme drought that ravaged the Caatinga in 2012–2016. We used random-intercepts generalized linear mixed models to account for microhabitat spatial clustering and for variations in bug-catch effort; we assessed model performance and computed model-averaged effect estimates using Akaike's information criterion. Pre-drought infestation was similar across microhabitat types; during the drought, infestation remained stable in dwellings and rocks but dropped in cacti. Pre-drought bug density declined from dwellings to rocks to cacti; an additional decline associated with the drought was largely comparable across microhabitats, albeit perhaps somewhat larger in cacti. Finally, pre-drought bug crowding was higher in dwellings than in rocks or cacti and changed little during the drought–possibly with a downward trend in dwellings and an upward trend in cacti. Conclusions: Triatoma brasiliensis populations fared better in dwellings and rocks than in cacti during extreme drought. Estimates of microhabitat and drought effects on infestation, density, and crowding suggest that only a few cacti (versus many rocks and dwellings) represent good-quality habitat under such extremely harsh conditions. Our findings provide empirical support to the microhabitat-quality hierarchy hypothesis, and imply that T. brasiliensis can endure extreme climate by exploiting high-quality microhabitats, whether wild or man-made, in the semiarid Caatinga. [ABSTRACT FROM AUTHOR]

The case-fatality rate of yellow fever virus (YFV) is one of the highest among arthropod-borne viruses (arboviruses). Although historically, the Asia-Pacific region has remained free of YFV, the risk of introduction has never been higher due to the increasing influx of people from endemic regions and the recent outbreaks in Africa and South America. Singapore is a global hub for trade and tourism and therefore at high risk for YFV introduction. Effective control of the main domestic mosquito vector Aedes aegypti in Singapore has failed to prevent re-emergence of dengue, chikungunya and Zika viruses in the last two decades, raising suspicions that peridomestic mosquito species untargeted by domestic vector control measures may contribute to arbovirus transmission. Here, we provide empirical evidence that the peridomestic mosquito Aedes malayensis found in Singapore can transmit YFV. Our laboratory mosquito colony recently derived from wild Ae. malayensis in Singapore was experimentally competent for YFV to a similar level as Ae. aegypti controls. In addition, we captured Ae. malayensis females in one human-baited trap during three days of collection, providing preliminary evidence that host-vector contact may occur in field conditions. Finally, we detected Ae. malayensis eggs in traps deployed in high-rise building areas of Singapore. We conclude that Ae. malayensis is a competent vector of YFV and re-emphasize that vector control methods should be extended to target peridomestic vector species. [ABSTRACT FROM AUTHOR]

Introduction: The prevalence of bacteremia caused by Gram negative non-fermentative (GNNF) bacteria has been increasing globally over the past decade. Many studies have investigated their epidemiology but focus on the common GNNF including Pseudomonas aeruginosa and Acinetobacter baumannii. Knowledge of the uncommon GNNF bacteremias is very limited. This study explores invasive bloodstream infection GNNF isolates that were initially unidentified after testing with standard microbiological techniques. All isolations were made during laboratory-based surveillance activities in two rural provinces of Thailand between 2006 and 2014. Methods: A subset of GNNF clinical isolates (204/947), not identified by standard manual biochemical methodologies were run on the BD Phoenix automated identification and susceptibility testing system. If an organism was not identified (12/204) DNA was extracted for whole genome sequencing (WGS) on a MiSeq platform and data analysis performed using 3 web-based platforms: Taxonomer, CGE KmerFinder and One Codex. Results: The BD Phoenix automated identification system recognized 92% (187/204) of the GNNF isolates, and because of their taxonomic complexity and high phenotypic similarity 37% (69/187) were only identified to the genus level. Five isolates grew too slowly for identification. Antimicrobial sensitivity (AST) data was not obtained for 93/187 (50%) identified isolates either because of their slow growth or their taxa were not in the AST database associated with the instrument. WGS identified the 12 remaining unknowns, four to genus level only. Conclusion: The GNNF bacteria are of increasing concern in the clinical setting, and our inability to identify these organisms and determine their AST profiles will impede treatment. Databases for automated identification systems and sequencing annotation need to be improved so that opportunistic organisms are better covered. [ABSTRACT FROM AUTHOR]

Background: The National Program for Chagas disease was implemented in Bolivia in 2006, and it greatly decreased the number of infections through vector control. Subsequently, a treatment regimen of benznidazole (BNZ) was started in seropositive school-age children living in certified vector control areas. Methods and findings: We conducted a 12-month follow-up study and seven blood samples were taken during and after the treatment. Serology, conventional diagnostic PCR (cPCR) and quantitative Real-time PCR (qPCR) were performed. Plasma Th1/Th2/Th17 cytokines levels were also determined. Approximately 73 of 103 seropositive children complied with BNZ, with three interruptions due to side effects. To evaluate each individual’s treatment efficacy, the cPCR and qPCR values during the final 6 months of the follow-up period were observed. Among 57 children who completed follow-up, 6 individuals (11%) showed both cPCR(+) and qPCR(+) (non reactive), 24 (42%) cPCR(-) but qPCR(+) (ambiguous) and 27 (47%) cPCR(-) and qPCR(-) (reactive). Within 14 Th1/Th2/Th17 cytokines, IL-17A showed significantly higher levels in seropositive children before the treatment compared to age-matched seronegative children and significantly decreased to the normal level one-year after. Moreover, throughout the follow-up study, IL-17A levels were positively co-related to parasite counts detected by qPCR. At the 12 months’ time point, IL-17A levels of non-reactive subjects were significantly higher than either those of reactive or ambiguous subjects suggesting that IL-17A might be useful to determine the reactivity to BNZ treatment. Conclusions: Plasma levels of IL-17A might be a bio-marker for detecting persistent infection of T. cruzi and its chronic inflammation. [ABSTRACT FROM AUTHOR]

Background: Lymphatic filariasis (LF) is a neglected tropical disease, and the Global Program to Eliminate LF delivers mass drug administration (MDA) to 500 million people every year. Adverse events (AEs) are common after LF treatment. Methodology/Principal findings: To better understand the pathogenesis of AEs, we studied LF-patients from a treatment trial. Plasma levels of many filarial antigens increased post-treatment in individuals with AEs, and this is consistent with parasite death. Circulating immune complexes were not elevated in these participants, and the classical complement cascade was not activated. Multiple cytokines increased after treatment in persons with AEs. A transcriptomic analysis was performed for nine individuals with moderate systemic AEs and nine matched controls. Differential gene expression analysis identified a significant transcriptional signature associated with post-treatment AEs; 744 genes were upregulated. The transcriptional signature was enriched for TLR and NF-κB signaling. Increased expression of seven out of the top eight genes upregulated in persons with AEs were validated by qRT-PCR, including TLR2. Conclusions/Significance: This is the first global study of changes in gene expression associated with AEs after treatment of lymphatic filariasis. Changes in cytokines were consistent with prior studies and with the RNAseq data. These results suggest that Wolbachia lipoprotein is involved in AE development, because it activates TLR2-TLR6 and downstream NF-κB. Additionally, LPS Binding Protein (LBP, which shuttles lipoproteins to TLR2) increased post-treatment in individuals with AEs. Improved understanding of the pathogenesis of AEs may lead to improved management, increased MDA compliance, and accelerated LF elimination. [ABSTRACT FROM AUTHOR]

Introduction: The widespread emergence of resistance to insecticides used to control adult Aedes mosquitoes has made traditional control strategies inadequate for the reduction of various vector populations. Therefore, complementary vector control methods, such as the Sterile Insect Technique, are needed to enhance existing efforts. The technique relies on the rearing and release of large numbers of sterile males, and the development of efficient and standardized mass-rearing procedures and tools is essential for its application against medically important mosquitoes. Methods: In the effort to reduce the cost of the rearing process, a prototype low-cost plexiglass mass-rearing cage has been developed and tested for egg production and egg hatch rate in comparison to the current Food and Agriculture Organization/International Atomic Energy Agency (FAO/IAEA) stainless-steel cage. Additionally, an adult-index was validated and used as a proxy to estimate the mosquito survival rates by counting the number of male and female mosquitoes that were resting within each of the 6 squares at a given point of time each day in the cage. Results: The study has shown that the prototype mass-rearing cage is cheap and is as efficient as the FAO/IAEA stainless-steel cage in terms of egg production, with even better overall egg hatch rate. The mean numbers of eggs per cage, after seven cycles of blood feeding and egg collection, were 969,789 ± 138,101 and 779,970 ± 123,042, corresponding to 81 ± 11 and 65 ± 10 eggs per female over her lifespan, in the prototype and the stainless-steel-mass-rearing cages, respectively. The longevity of adult male and female mosquitoes was not affected by cage type and, the adult-index could be considered as an appropriate proxy for survival. Moreover, the mass-rearing cage prototype is easy to handle and transport and improves economic and logistic efficiency. Conclusion: The low-cost mass-rearing prototype cage can be recommended to produce Ae. aegypti in the context of rear and release techniques. The proposed adult-index can be used as a quick proxy of mosquito survival rates in mass-rearing settings. [ABSTRACT FROM AUTHOR]

Background: Human mobility plays a central role in shaping pathogen transmission by generating spatial and/or individual variability in potential pathogen-transmitting contacts. Recent research has shown that symptomatic infection can influence human mobility and pathogen transmission dynamics. Better understanding the complex relationship between symptom severity, infectiousness, and human mobility requires quantification of movement patterns throughout infectiousness. For dengue virus (DENV), human infectiousness peaks 0–2 days after symptom onset, making it paramount to understand human movement patterns from the beginning of illness. Methodology and principal findings: Through community-based febrile surveillance and RT-PCR assays, we identified a cohort of DENV+ residents of the city of Iquitos, Peru (n = 63). Using retrospective interviews, we measured the movements of these individuals when healthy and during each day of symptomatic illness. The most dramatic changes in mobility occurred during the first three days after symptom onset; individuals visited significantly fewer locations (Wilcoxon test, p = 0.017) and spent significantly more time at home (Wilcoxon test, p = 0.005), compared to when healthy. By 7–9 days after symptom onset, mobility measures had returned to healthy levels. Throughout an individual’s symptomatic period, the day of illness and their subjective sense of well-being were the most significant predictors for the number of locations and houses they visited. Conclusions/Significance: Our study is one of the first to collect and analyze human mobility data at a daily scale during symptomatic infection. Accounting for the observed changes in human mobility throughout illness will improve understanding of the impact of disease on DENV transmission dynamics and the interpretation of public health-based surveillance data. [ABSTRACT FROM AUTHOR]

Introduction: In Tunisia, almost 77% of clinically and bacteriologically diagnosed cases of extrapulmonary tuberculosis (EPTB) are zoonotic TB, caused by M. bovis. Although several studies have analyzed bovine TB in cattle in Tunisia, no study has evaluated the risk of transmission to humans in such an endemic country. We aimed to study the genetic diversity of M. bovis human isolates, to ascertain the causes of human EPTB infection by M. bovis and to investigate the distribution and population structure of this species in Tunisia. Materials and methods: A total of 110 M. bovis isolates taken from patients with confirmed EPTB were characterized by spoligotyping and MIRU-VNTR typing methods. Results: Among the 15 spoligotypes detected in our study, 6 (SB0120, SB0121, SB2025, SB1200, SB1003 and SB0134) were the most prevalent (83.5%) of which SB0120, SB0121 and SB2025 were the most prevailing. MIRU-VNTR typing method showed a high genotypic and genetic diversity. The genetic differentiation based on MIRU-VNTR was significant between populations from South East (Tataouine, Medenine) and Central West (Gafsa, Sidi Bouzid, Kasserine) regions. Of note, 13/15 (86.7%) spoligotypes detected in our study were previously identified in cattle in Tunisia with different frequencies suggesting a peculiar ability of some genotypes to infect humans. Using combined spoligotyping and MIRU-VNTR method, a high clustering rate of 43.9% was obtained. Our results underlined that human EPTB due to M. bovis was more commonly found in female gender and in young patients. Most of our patients, 66.4% (73/110) were raw milk or derivatives consumers, whereas 30.9% (34/110) patients would have contracted EPTB through contact with livestock. The findings suggest that the transmission of Zoonotic TB caused by M. bovis to humans mainly occurred by oral route through raw milk or derivatives. Conclusion: Our study showed the urgent need of a better veterinary control with the implementation of effective and comprehensive strategies in order to reach a good protection of animals as well as human health. [ABSTRACT FROM AUTHOR]

Lymphatic filariasis (LF), a morbid disease caused by the tissue-invasive nematodes Wuchereria bancrofti, Brugia malayi, and Brugia timori, affects millions of people worldwide. Global eradication efforts have significantly reduced worldwide prevalence, but complete elimination has been hampered by limitations of current anti-filarial drugs and the lack of a vaccine. The goal of this study was to evaluate B. malayi intestinal UDP-glucuronosyltransferase (Bm-UGT) as a potential therapeutic target. To evaluate whether Bm-UGT is essential for adult filarial worms, we inhibited its expression using siRNA. This resulted in a 75% knockdown of Bm-ugt mRNA for 6 days and almost complete suppression of detectable Bm-UGT by immunoblot. Reduction in Bm-UGT expression resulted in decreased worm motility for 6 days, 70% reduction in microfilaria release from adult worms, and significant reduction in adult worm metabolism as detected by MTT assays. Because prior allergic-sensitization to a filarial antigen would be a contraindication for its use as a vaccine candidate, we tested plasma from infected and endemic normal populations for Bm-UGT-specific IgE using a luciferase immunoprecipitation assay. All samples (n = 35) tested negative. We then tested two commercially available medicines known to be broad inhibitors of UGTs, sulfinpyrazone and probenecid, for in vitro activity against B. malayi. There were marked macrofilaricidal effects at concentrations achievable in humans and very little effect on microfilariae. In addition, we observed that probenecid and sulfinpyrazone exhibit a synergistic macrofilaricidal effect when used in combination with albendazole. The results of this study demonstrate that Bm-UGT is an essential protein for adult worm survival. Lack of prior IgE sensitization in infected and endemic populations suggest it may be a feasible vaccine candidate. The finding that sulfinpyrazone and probenecid have in vitro effects against adult B. malayi worms suggests that these medications have promise as potential macrofilaricides in humans. [ABSTRACT FROM AUTHOR]

Background: The diagnosis of schistosomiasis currently relies on microscopic detection of schistosome eggs in stool or urine samples and serological assays. The poor sensitivity of standard microscopic procedures performed in routine laboratories, makes molecular detection methods of increasing interest. The aim of the study was to evaluate two in-house real-time Schistosoma PCRs, targeting respectively S. mansoni [Sm] and S. haematobium [Sh] in excreta, biopsies and sera as potential tools to diagnose active infections and to monitor treatment efficacy. Methods: Schistosoma PCRs were performed on 412 samples (124 urine, 86 stools, 8 biopsies, 194 sera) from patients with suspected schistosomiasis, before anti-parasitic treatment. Results were compared to microscopic examination and serological assays (enzyme-linked immunosorbent assay (ELISA), indirect haemagglutination (HA) and Western Blot (WB) assay). Results: Compared to microscopy, PCRs significantly increased the sensitivity of diagnosis, from 4% to 10.5% and from 33.7% to 48.8%, for Sh in urine and Sm in stools, respectively. The overall sensitivity of PCR on serum samples was 72.7% and reached 94.1% in patients with positive excreta (microscopy). The specificity of serum PCR was 98.9%. After treatment, serum PCR positivity rates slowly declined from 93.8% at day 30 to 8% at day 360, whereas antibody detection remained positive after 1 year. Conclusion: Schistosoma PCRs clearly outperform standard microscopy on stools and urine and could be part of reference methods combined with WB-based serology, which remains a gold standard for initial diagnosis. When serological assays are positive and microscopy is negative, serum PCRs provide species information to guide further clinical exploration. Biomarkers such as DNA and antibodies are of limited relevance for early treatment monitoring but serum PCR could be useful when performed at least 1 year after treatment to help confirm a cured infection. [ABSTRACT FROM AUTHOR]

Background: Identification of blood sources of hematophagous arthropods is crucial for understanding the transmission cycles of vector-borne diseases. Many different approaches towards host determination were proposed, including precipitin test, ELISA, DNA- and mass spectrometry-based methods; yet all face certain complications and limitations, mostly related to blood degradation. This study presents a novel method for blood meal identification, peptide mass mapping (PMM) analysis of host-specific hemoglobin peptides using MALDI-TOF mass spectrometry. Methodology/Principal findings: To identify blood meal source, proteins from abdomens of engorged sand fly females were extracted, cleaved by trypsin and peptide fragments of host hemoglobin were sequenced using MALDI-TOF MS. The method provided correct host identification of 100% experimentally fed sand flies until 36h post blood meal (PBM) and for 80% samples even 48h PBM. In females fed on two hosts, both blood meal sources were correctly assigned for 60% of specimens until 36h PBM. In a validation study on field-collected females, the method yielded unambiguous host determination for 96% of specimens. The suitability of PMM-based MALDI-TOF MS was proven experimentally also on lab-reared Culex mosquitoes. Conclusions/Significance: PMM-based MALDI-TOF MS analysis targeting host specific hemoglobin peptides represents a sensitive and cost-effective method with a fast and simple preparation protocol. As demonstrated here on phlebotomine sand flies and mosquitoes, it allows reliable and rapid blood source determination even 48h PBM with minimal material input and provides more robust and specific results than other currently used methods. This approach was also successfully tested on field-caught engorged females and proved to be a promising useful tool for large-scale screening of host preferences studies. Unlike other methods including MALDI-TOF protein profiling, it allows correct identification of mixed blood meals as was demonstrated on both experimentally fed and field-collected sand flies. [ABSTRACT FROM AUTHOR]

Background: Population suppression through mass-release of Aedes aegypti males carrying dominant-lethal transgenes has been demonstrated in the field. Where population dynamics show negative density-dependence, suppression can be enhanced if lethality occurs after the density-dependent (i.e. larval) stage. Existing molecular tools have limited current examples of such Genetic Pest Management (GPM) systems to achieving this through engineering ‘cell-autonomous effectors’ i.e. where the expressed deleterious protein is restricted to the cells in which it is expressed–usually under the control of the regulatory elements (e.g. promoter regions) used to build the system. This limits the flexibility of these technologies as regulatory regions with useful spatial, temporal or sex-specific expression patterns may only be employed if the cells they direct expression in are simultaneously sensitive to existing effectors, and also precludes the targeting of extracellular regions such as cell-surface receptors. Expanding the toolset to ‘non-cell autonomous’ effectors would significantly reduce these limitations. Methodology/Principal findings: We sought to engineer female-specific, late-acting lethality through employing the Ae. aegypti VitellogeninA1 promoter to drive blood-meal-inducible, fat-body specific expression of tTAV. Initial attempts using pro-apoptotic effectors gave no evident phenotype, potentially due to the lower sensitivity of terminally-differentiated fat-body cells to programmed-death signals. Subsequently, we dissociated the temporal and spatial expression of this system by engineering a novel synthetic effector (Scorpion neurotoxin–TetO-gp67.AaHIT) designed to be secreted out of the tissue in which it was expressed (fat-body) and then affect cells elsewhere (neuro-muscular junctions). This resulted in a striking, temporary-paralysis phenotype after blood-feeding. Conclusions/Significance: These results are significant in demonstrating for the first time an engineered ‘action at a distance’ phenotype in a non-model pest insect. The potential to dissociate temporal and spatial expression patterns of useful endogenous regulatory elements will extend to a variety of other pest insects and effectors. [ABSTRACT FROM AUTHOR]

Background: Histoplasmosis is a neglected disease that affects mainly immunocompromised patients, presenting a progressive dissemination pattern and a high mortality rate, mainly due to delayed diagnosis, caused by slow fungal growth in culture. Therefore, a fast, suitable and cost-effective assay is required for the diagnosis of histoplasmosis in resource-limited laboratories. This study aimed to develop and evaluate two new molecular approaches for a more cost-effective diagnosis of histoplasmosis. Methodology: Seeking a fast, suitable, sensitive, specific and low-cost molecular detection technique, we developed a new Loop-mediated Isothermal Amplification (LAMP) assay and nested PCR, both targeting the Internal Transcribed Spacer (ITS) multicopy region of Histoplasma capsulatum. The sensitivity was evaluated using 26 bone marrow and 1 whole blood specimens from patients suspected to have histoplasmosis and 5 whole blood samples from healthy subjects. All specimens were evaluated in culture, as a reference standard test, and Hcp100 nPCR, as a molecular reference test. A heparin-containing whole blood sample from a heathy subject was spiked with H. capsulatum cells and directly assayed with no previous DNA extraction. Results: Both assays were able to detect down to 1 fg/μL of H. capsulatum DNA, and ITS LAMP results could also be revealed to the naked-eye by adding SYBR green to the reaction tube. In addition, both assays were able to detect all clades of Histoplasma capsulatum cryptic species complex. No cross-reaction with other fungal pathogens was presented. In comparison with Hcp100 nPCR, both assays reached 83% sensitivity and 92% specificity. Furthermore, ITS LAMP assay showed no need for DNA extraction, since it could be directly applied to crude whole blood specimens, with a limit of detection of 10 yeasts/μL. Conclusion: ITS LAMP and nPCR assays have the potential to be used in conjunction with culture for early diagnosis of progressive disseminated histoplasmosis, allowing earlier, appropriate treatment of the patient. The possibility of applying ITS LAMP, as a direct assay, with no DNA extraction and purification steps, makes it suitable for resource-limited laboratories. However, more studies are necessary to validate ITS LAMP and nPCR as direct assay in other types of clinical specimens. [ABSTRACT FROM AUTHOR]

Zika virus (ZIKV) is a newly-identified infectious cause of congenital disease. Transplacental transfer of maternal IgG to the fetus plays an important role in preventing many neonatal infections. However, antibody transfer may also have negative consequences, such as mediating enhancement of flavivirus infections in early life, or trafficking of virus immune complexes to the fetal compartment. ZIKV infection produces placental pathology which could lead to impaired IgG transfer efficiency as occurs in other maternal infections, such as HIV-1 and malaria. In this study, we asked whether ZIKV infection during pregnancy impairs transplacental transfer of IgG. We enrolled pregnant women with fever or rash in a prospective cohort in Vitoria, Brazil during the recent ZIKV epidemic. ZIKV and dengue virus (DENV)-specific IgG, ZIKV and DENV neutralizing antibodies, and routine vaccine antigen-specific IgG were measured in maternal samples collected around delivery and 20 paired cord blood samples. We concluded that 8 of these mothers were infected with ZIKV during pregnancy and 12 were ZIKV-uninfected. The magnitude of flavivirus-specific IgG, neutralizing antibody, and vaccine-elicited IgG were highly correlated between maternal plasma and infant cord blood in both ZIKV-infected and -uninfected mother-infant pairs. Moreover, there was no difference in the magnitude of plasma flavivirus-specific IgG levels between mothers and infants regardless of ZIKV infection status. Our data suggests that maternal ZIKV infection during pregnancy does not impair the efficiency of placental transfer of flavivirus-specific, functional, and vaccine-elicited IgG. These findings have implications for the neonatal outomes of maternal ZIKV infection and optimal administration of antibody-based ZIKV vaccines and therapeutics. [ABSTRACT FROM AUTHOR]

Ticks successfully feed and transmit pathogens by injecting pharmacological compounds in saliva to thwart host defenses. We have previously used LC-MS/MS to identify proteins that are present in saliva of unfed Amblyomma americanum ticks that were exposed to different hosts. Here we show that A. americanum serine protease inhibitor (serpin) 27 (AAS27) is an immunogenic saliva protein that is injected into the host within the first day of tick feeding and is an anti-inflammatory protein that might act by blocking plasmin and trypsin functions. Although AAS27 is injected into the host throughout tick feeding, qRT-PCR and western blotting analyses indicate that the respective transcript and protein are present in high amounts within the first 24 h of tick feeding. Biochemical screening of Pichia pastoris-expressed recombinant (r) AAS27 against mammalian proteases related to host defense shows it is an inhibitor of trypsin and plasmin, with stoichiometry of inhibition indices of 3.5 and 3.8, respectively. Consistent with typical inhibitory serpins, rAAS27 formed heat- and SDS-stable irreversible complexes with both proteases. We further demonstrate that rAAS27 inhibits trypsin with ka of 6.46 ± 1.24 x 104 M-1 s-1, comparable to serpins of other tick species. We show that native AAS27 is part of the repertoire of proteins responsible for the inhibitory activity against trypsin in crude tick saliva. AAS27 is likely utilized by the tick to evade the hosts inflammation defense since rAAS27 blocks both formalin and compound 48/80-induced inflammation in rats. Tick immune sera of rabbits that had acquired resistance against tick feeding following repeated infestations with A. americanum or Ixodes scapularis ticks reacts with rAAS27. Of significant interest, antibody to rAAS27 blocks this serpin inhibitory functions. Taken together, we conclude that AAS27 is an anti-inflammatory protein secreted into the host during feeding and may represent a potential candidate for development of an anti-tick vaccine. [ABSTRACT FROM AUTHOR]

Urbanization is one of the major drivers of dengue epidemics globally. In Kenya, an intriguing pattern of urban dengue virus epidemics has been documented in which recurrent epidemics are reported from the coastal city of Mombasa, whereas no outbreaks occur in the two major inland cities of Kisumu and Nairobi. In an attempt to understand the entomological risk factors underlying the observed urban dengue epidemic pattern in Kenya, we evaluated vector density, human feeding patterns, vector genetics, and prevailing environmental temperature to establish how these may interact with one another to shape the disease transmission pattern. We determined that (i) Nairobi and Kisumu had lower vector density and human blood indices, respectively, than Mombasa, (ii) vector competence for dengue-2 virus was comparable among Ae. aegypti populations from the three cities, with no discernible association between susceptibility and vector cytochrome c oxidase subunit 1 gene variation, and (iii) vector competence was temperature-dependent. Our study suggests that lower temperature and Ae. aegypti vector density in Nairobi may be responsible for the absence of dengue outbreaks in the capital city, whereas differences in feeding behavior, but not vector competence, temperature, or vector density, contribute in part to the observed recurrent dengue epidemics in coastal Mombasa compared to Kisumu. [ABSTRACT FROM AUTHOR]

Zika virus (ZIKV), an emerging arbovirus belonging to the genus Flavivirus, is transmitted by Aedes mosquitoes. ZIKV infection can cause microcephaly of newborn babies and Guillain–Barré syndrome in adults. Because no licensed vaccine or specific antiviral treatment is available for ZIKV infection, the most commonly used approach to control the spread of ZIKV is suppression of the mosquito vector population. A novel proposed strategy to block arthropod virus (arbovirus) transmission is based on the chemical inhibition of virus infection in mosquitoes. However, only a few drugs and compounds have been tested with such properties. Here we present a comprehensive screen of 55 FDA-approved anti-flaviviral drugs for potential anti-ZIKV and mosquitocidal activity. Four drugs (auranofin, actinomycin D (Act-D), bortezomib and gemcitabine) were toxic to C6/36 cells, and two drugs (5-fluorouracil and mycophenolic acid (MPA)) significantly reduced ZIKV production in C6/36 cells at 2 μM and 0.5 μM, respectively. Three drugs (Act-D, cyclosporin A, ivermectin) exhibited a strong adulticidal activity, and six drugs (U18666A, retinoic acid p-hydroxyanilide (4-HPR), clotrimazole, bortezomib, MPA, imatinib mesylate) significantly suppressed ZIKV infection in mosquito midguts. Some of these FDA-approved drugs may have potential for use for the development of ZIKV transmission-blocking strategies. [ABSTRACT FROM AUTHOR]

Objective: Where human African trypanosomiasis (HAT) patients are seen, failure to microscopically diagnose infections by Trypanosoma brucei gambiense in blood smears and/or cerebrospinal fluid (CSF) in the critical early stages of the disease is the single most important factor in treatment failure, a result of delayed treatment onset or its absence. We hypothesized that the enhanced sensitivity of detergent-enhanced loop-mediated isothermal amplification (LAMP) will allow for point of care (POC) detection of African trypanosomes in the CSF of HAT patients where the probability for detecting a single parasite or parasite DNA molecule in 1 μL of CSF sample is negligible by current methods. Methodology: We used LAMP targeting the multicopy pan-T. brucei repetitive insertion mobile element (RIME LAMP) and the Trypanosoma brucei gambiense 5.8S rRNA-internal transcribed spacer 2 gene (TBG1 LAMP). We tested 1 μL out of 20 μL sham or Triton X-100 treated CSFs from 73 stage-1 and 77 stage-2 HAT patients from the Central African Republic and 100 CSF negative controls. Results: Under sham conditions, parasite DNA was detected by RIME and TBG1 LAMP in 1.4% of the stage-1 and stage-2 gambiense HAT CSF samples tested. After sample incubation with detergent, the number of LAMP parasite positive stage-2 CSF’s increased to 26%, a value which included the 2 of the 4 CSF samples where trypanosomes were identified microscopically. Unexpected was the 41% increase in parasite positive stage-1 CSF’s detected by LAMP. Cohen’s kappa coefficients for RIME versus TBG1 LAMP of 0.92 (95%CI: 0.82–1.00) for stage-1 and 0.90 (95%CI: 0.80–1.00) for stage-2 reflected a high level of agreement between the data sets indicating that the results were not due to amplicon contamination, data confirmed in χ2 tests (p<0.001) and Fisher’s exact probability test (p = 4.7e-13). Conclusion: This study detected genomic trypanosome DNA in the CSF independent of the HAT stage and may be consistent with early CNS entry and other scenarios that identify critical knowledge gaps for future studies. Detergent-enhanced LAMP could be applicable for non-invasive African trypanosome detection in human skin and saliva or as an epidemiologic tool for the determination of human (or animal) African trypanosome prevalence in areas where chronically low parasitemias are present. [ABSTRACT FROM AUTHOR]

Despite provision of preventive measures against schistosomiasis such as mass drug administration (MDA), the prevalence of Schistosoma mansoni remains high in communities living near Lake Victoria. This study aimed to analyse the status of schistosomiasis, including its prevalence, health education, knowledge, attitudes, and practices (KAP) among pupils, and water use in schools in Mbita situated along the shores of Lake Victoria. Four primary schools were selected as target schools and pupils in classes six and seven were recruited as study participants. The prevalence of S. mansoni was examined by Kato-Katz method. Simultaneously, a KAP survey toward schistosomiasis was conducted among the pupils. Health education contents were extracted from textbooks. All primary schools in the study site were surveyed regarding how each secured water used for daily school life. The prevalence of S. mansoni was 56% and 36% in 2015 and 2016, respectively. 60–70% of pupils chose a correct answer for the mode of transmission. More than 70% of pupils answered that bathing in Lake Victoria causes Schistosoma infection; however, more than 70% of pupils bathed in Lake Victoria sometimes or every day. According to the science textbook, “avoiding contact with contaminated water” is the way to prevent schistosomiasis; however, 66% of schools asked pupils to bring water from Lake Victoria. The prevalence of S. mansoni among pupils remains high. Schoolchildren are taught to avoid contact with contaminated water but are often asked to fetch water from the lake. From the school health viewpoint, health education that reflects the social and cultural context of the community in the contents and teaching methods are needed. In addition to this, provision of sanitation infrastructure is needed. A comprehensive and innovative approach which harmonises central and local governments and other stakeholders, as well as community is important to prevent schistosomiasis. [ABSTRACT FROM AUTHOR]

Background: Babesia, a tick-borne genus of intraerythrocytic parasites, is understudied in humans outside of established high-endemic areas. There is a paucity of data on Babesia in Africa, despite evidence that it is regionally present. A pilot study suggested that Babesia was present in a rural district of Tanzania. Methodology/Principal findings: A cross-sectional study was conducted July-August 2017: residents in a case hamlet that had clustering of subjects with high signal-to-cut off (S/CO) ratios for antibodies against B. microti in the pilot study, and a control hamlet that had lacked significant signal, were evaluated for B. microti. Subjects aged ≥15yrs (n = 299) underwent clinical evaluation and household inspections; 10ml whole blood was drawn for Babesia transcription mediated amplification (TMA), B. microti indirect fluorescent antibody testing (IFA) and rapid diagnostic testing (RDT) for Plasmodium spp. Subjects aged <15yrs (n = 266) underwent a RDT for Plasmodium and assessment by ELISA for B. microti antibodies. A total of 570 subjects participated (mean age 22 [<1 to 90yrs]) of whom 50.7% were female and 145 (25.5%) subjects were Plasmodium RDT positive (+). In those <15yrs, the median ELISA S/CO was 1.11 (IQR 0.80–1.48); the median S/CO in the case (n = 120) and control (n = 146) hamlets was 1.19 (IQR 0.81–1.48) and 1.06 (IQR 0.80–1.50) respectively (p = 0.4). Children ≥5yrs old were more likely to have a higher S/CO ratio than those <5yrs old (p<0.001). One hundred (38%) subjects <15yrs were Plasmodium RDT+. The median S/CO ratio (children <15yrs) did not differ by RDT status (p = 0.15). In subjects ≥15yrs, no molecular test was positive for Babesia, but four subjects (1.4%) were IFA reactive (two each at titers of 128 and 256). Conclusions/Significance: The findings offer further support for Babesia in rural Tanzania. However, low prevalence of seroreactivity questions its clinical significance. [ABSTRACT FROM AUTHOR]

In 1994, combined active and passive screening reported 1469 cases from the historic Gambian Human African Trypanosomiasis (gHAT) foci of West Nile, Uganda. Since 2011 systematic active screening has stopped and there has been reliance on passive screening. During 2014, passive screening alone detected just nine cases. In the same year a tsetse control intervention was expanded to cover the main gHAT foci in West Nile to curtail transmission of gHAT contributing to the elimination of gHAT as a public health problem in the area. It is known that sole reliance on passive screening is slow to detect cases and can underestimate the actual true number. We therefore undertook an active screening programme designed to test the efficacy of these interventions against gHAT transmission and clarify disease status. Screening was conducted in 28 randomly selected villages throughout the study area, aiming to sample all residents. Whole blood from 10,963 participants was analysed using CATT and 97 CATT suspects (0.9%) were evaluated with microscopy and trypanolysis. No confirmed cases were found providing evidence that the gHAT prevention programmes in West Nile have been effective. Results confirm gHAT prevalence in the study area of West Nile is below the elimination threshold (1 new case / 10,000 population), making elimination on course across this study area if status is maintained. The findings of this study can be used to guide future HAT and tsetse management in other gHAT foci, where reduced caseloads necessitate a shift from active to passive screening. [ABSTRACT FROM AUTHOR]

Background: To be transmitted to vertebrate hosts via the saliva of their vectors, arthropod-borne viruses have to cross several barriers in the mosquito body, including the midgut infection and escape barriers. Yellow fever virus (YFV) belongs to the genus Flavivirus, which includes human viruses transmitted by Aedes mosquitoes, such as dengue and Zika viruses. The live-attenuated YFV-17D vaccine has been used safely and efficiently on a large scale since the end of World War II. Early studies have shown, using viral titration from salivary glands of infected mosquitoes, that YFV-17D can infect Aedes aegypti midgut, but does not disseminate to other tissues. Methodology/Principal findings: Here, we re-visited this issue using a panel of techniques, such as RT-qPCR, Western blot, immunofluorescence and titration assays. We showed that YFV-17D replication was not efficient in Aedes aegypti midgut, as compared to the clinical isolate YFV-Dakar. Viruses that replicated in the midgut failed to disseminate to secondary organs. When injected into the thorax of mosquitoes, viruses succeeded in replicating into midgut-associated tissues, suggesting that, during natural infection, the block for YFV-17D replication occurs at the basal membrane of the midgut. Conclusions/Significance: The two barriers associated with Ae. aegypti midgut prevent YFV-17D replication. Our study contributes to our basic understanding of vector–pathogen interactions and may also aid in the development of non-transmissible live virus vaccines. [ABSTRACT FROM AUTHOR]

Enteric fevers, caused by the Salmonella enterica serovars Typhi (ST), Paratyphi A (PA) and Paratyphi B (PB), are life-threatening illnesses exhibiting very similar clinical symptoms but with distinct epidemiologies, geographical distributions and susceptibilities to antimicrobial treatment. Nevertheless, the mechanisms by which the host recognizes pathogens with high levels of homology, such as these bacterial serovars, remain poorly understood. Using a three-dimensional organotypic model of the human intestinal mucosa and PA, PB, and ST, we observed significant differences in the secretion patterns of pro-inflammatory cytokines and chemokines elicited by these serovars. These cytokines/chemokines were likely to be co-regulated and influenced the function of epithelial cells, such as the production of IL-8. We also found differing levels of polymorphonuclear leukocyte (PMN) migration among various infection conditions that either included or excluded lymphocytes and macrophages (Mϕ), strongly suggesting feedback mechanisms among these cells. Blocking experiments showed that IL-1β, IL-6, IL-8, TNF-α and CCL3 cytokines were involved in the differential regulation of migration patterns. We conclude that the crosstalk among the lymphocytes, Mϕ, PMN and epithelial cells is cytokine/chemokine-dependent and bacterial-serotype specific, and plays a pivotal role in orchestrating the functional efficiency of the innate cells and migratory characteristics of the leukocytes. [ABSTRACT FROM AUTHOR]

Background: Visceral leishmaniasis (VL) in Brazil is a neglected, vector-borne, tropical parasitic disease that is responsible for several thousand human deaths every year. The transmission route involves sand flies becoming infected after feeding on infected reservoir host, mainly dogs, and then transmitting the Leishmania infantum parasites while feeding on humans. A major component of the VL control effort is the identification and euthanasia of infected dogs to remove them as a source of infection. A rapid, non-invasive, point-of-care device able to differentiate between the odours of infected and uninfected dogs may contribute towards the accurate diagnosis of canine VL. Methodology/Principal findings: We analysed the headspace volatile chemicals from the hair of two groups of dogs collected in 2017 and 2018 using a bench-top eNose volatile organic chemical analyser. The dogs were categorised as infected or uninfected by PCR analysis of blood samples taken by venepuncture and the number of parasites per ml of blood was calculated for each dog by qPCR analysis. We demonstrated using a robust clustering analysis that the eNose data could be discriminated into infected and uninfected categories with specificity >94% and sensitivity >97%. The eNose device and data analysis were sufficiently sensitive to be able to identify infected dogs even when the Leishmania population in the circulating blood was very low. Conclusions/Significance: The study illustrates the potential of the eNose to rapidly and accurately identify dogs infected with Le. infantum. Future improvements to eNose analyser sensor sensitivity, sampling methodology and portability suggest that this approach could significantly improve the diagnosis of VL infected dogs in Brazil with additional potential for effective diagnosis of VL in humans as well as for the diagnosis of other parasitic diseases. [ABSTRACT FROM AUTHOR]

Depletion of Wolbachia endosymbionts of human pathogenic filariae using 4–6 weeks of doxycycline treatment can lead to permanent sterilization and adult filarial death. We investigated the anti-Wolbachia drug candidate ABBV-4083 in the Litomosoides sigmodontis rodent model to determine Wolbachia depletion kinetics with different regimens. Wolbachia reduction occurred in mice as early as 3 days after the initiation of ABBV-4083 treatment and continued throughout a 10-day treatment period. Importantly, Wolbachia levels continued to decline after a 5-day-treatment from 91.5% to 99.9% during a 3-week washout period. In jirds, two weeks of ABBV-4083 treatment (100mg/kg once-per-day) caused a >99.9% Wolbachia depletion in female adult worms, and the kinetics of Wolbachia depletion were recapitulated in peripheral blood microfilariae. Similar to Wolbachia depletion, inhibition of embryogenesis was time-dependent in ABBV-4083-treated jirds, leading to a complete lack of late embryonic stages (stretched microfilariae) and lack of peripheral microfilariae in 5/6 ABBV-4083-treated jirds by 14 weeks after treatment. Twice daily treatment in comparison to once daily treatment with ABBV-4083 did not significantly improve Wolbachia depletion. Moreover, up to 4 nonconsecutive daily treatments within a 14-dose regimen did not significantly erode Wolbachia depletion. Within the limitations of an animal model that does not fully recapitulate human filarial disease, our studies suggest that Wolbachia depletion should be assessed clinically no earlier than 3–4 weeks after the end of treatment, and that Wolbachia depletion in microfilariae may be a viable surrogate marker for the depletion within adult worms. Furthermore, strict daily adherence to the dosing regimen with anti-Wolbachia candidates may not be required, provided that the full regimen is subsequently completed. [ABSTRACT FROM AUTHOR]

The 2013–2016 Ebola virus outbreak in West Africa was the largest and deadliest outbreak to date. Here we conducted a serological study to examine the antibody levels in survivors and the seroconversion in close contacts who took care of Ebola-infected individuals, but did not develop symptoms of Ebola virus disease. In March 2017, we collected blood samples from 481 individuals in Makeni, Sierra Leone: 214 survivors and 267 close contacts. Using commercial, quantitative ELISAs, we tested the plasma for IgG-specific antibodies against three major viral antigens: GP, the only viral glycoprotein expressed on the virus surface; NP, the most abundant viral protein; and VP40, a major structural protein of Zaire ebolavirus. We also determined neutralizing antibody titers. In the cohort of Ebola survivors, 97.7% of samples (209/214) had measurable antibody levels against GP, NP, and/or VP40. Of these positive samples, all but one had measurable neutralizing antibody titers against Ebola virus. For the close contacts, up to 12.7% (34/267) may have experienced a subclinical virus infection as indicated by detectable antibodies against GP. Further investigation is warranted to determine whether these close contacts truly experienced subclinical infections and whether these asymptomatic infections played a role in the dynamics of transmission. [ABSTRACT FROM AUTHOR]

Typhoid fever is endemic across sub-Saharan Africa. However, estimates of the burden of typhoid are undermined by insufficient blood volumes and lack of sensitivity of blood culture. Here, we aimed to address this limitation by exploiting pre-enrichment culture followed by PCR, alongside routine blood culture to improve typhoid case detection. We carried out a prospective diagnostic cohort study and enrolled children (aged 0–4 years) with non-specific febrile disease admitted to a tertiary hospital in Blantyre, Malawi from August 2014 to July 2016. Blood was collected for culture (BC) and real-time PCR after a pre-enrichment culture in tryptone soy broth and ox-bile. DNA was subjected to PCR for invA (Pan-Salmonella), staG (S. Typhi), and fliC (S. Typhimurium) genes. A positive PCR was defined as invA plus either staG or fliC (CT<29). IgM and IgG ELISA against four S. Typhi antigens was also performed. In total, 643 children (median age 1.3 years) with nonspecific febrile disease were enrolled; 31 (4.8%) were BC positive for Salmonella (n = 13 S. Typhi, n = 16 S. Typhimurium, and n = 2 S. Enteritidis). Pre-enrichment culture of blood followed by PCR identified a further 8 S. Typhi and 15 S. Typhimurium positive children. IgM and IgG titres to the S. Typhi antigen STY1498 (haemolysin) were significantly higher in children that were PCR positive but blood culture negative compared to febrile children with all other non-typhoid illnesses. The addition of pre-enrichment culture and PCR increased the case ascertainment of invasive Salmonella disease in children by 62–94%. These data support recent burden estimates that highlight the insensitivity of blood cultures and support the targeting of pre-school children for typhoid vaccine prevention in Africa. Blood culture with real-time PCR following pre-enrichment should be used to further refine estimates of vaccine effectiveness in typhoid vaccine trials. [ABSTRACT FROM AUTHOR]

The N-linked glycosylation motif at amino acid position 154–156 of the envelope (E) protein of West Nile virus (WNV) is linked to enhanced murine neuroinvasiveness, avian pathogenicity and vector competence. Naturally occurring isolates with altered E protein glycosylation patterns have been observed in WNV isolates; however, the specific effects of these polymorphisms on avian host pathogenesis and vector competence have not been investigated before. In the present study, amino acid polymorphisms, NYT, NYP, NYF, SYP, SYS, KYS and deletion (A’DEL), were reverse engineered into a parental WNV (NYS) cDNA infectious clone to generate WNV glycosylation mutant viruses. These WNV glycosylation mutant viruses were characterized for in vitro growth, pH-sensitivity, temperature-sensitivity and host competence in American crows (AMCR), house sparrows (HOSP) and Culex quinquefasciatus. The NYS and NYT glycosylated viruses showed higher viral replication, pH and temperature sensitivity than NYP, NYF, SYP, SYS, KYS and A’DEL viruses in vitro. Interestingly, in vivo results demonstrated asymmetric effects in avian and mosquito competence that were independent of the E-protein glycosylation status. In AMCRs and HOSPs, all viruses showed comparable viremias with the exception of NYP and KYS viruses that showed attenuated phenotypes. Only NYP showed reduced vector competence in both Cx. quinquefasciatus and Cx. tarsalis. Glycosylated NYT exhibited similar avian virulence properties as NYS, but resulted in higher mosquito oral infectivity than glycosylated NYS and nonglycosylated, NYP, NYF, SYP and KYS mutants. These data demonstrated that amino acid polymorphisms at E154/156 dictate differential avian host and vector competence phenotypes independent of E-protein glycosylation status. [ABSTRACT FROM AUTHOR]

We studied infection by Trypanosomatidae in bats captured in two areas with different degradation levels in the Atlantic Forest of Rio de Janeiro state: Reserva Ecológica de Guapiaçu (REGUA) and Estação Fiocruz Mata Atlântica (EFMA). Furthermore, we evaluated whether the diversity of trypanosomatids changes according to bat diversity and the different levels of preservation in the region. The results showed no influence of the level of preservation on bat species richness (15 and 14 species, respectively), with similar chiropterofauna and higher abundance of two common fruit-eating bat species in the tropics: Carollia perspicillata and Artibeus lituratus. Of the 181 bat specimens analyzed by LIT/Schneider hemoculture, we detected 24 infected individuals (13%), including one positive Sturnira lilium individual that was also positive by fresh blood examination. Molecular characterization using nested PCR targeting the 18 SSU rRNA-encoding gene fragment showed similar trypanosomatid infection rates in bats from the two areas: 15% in REGUA and 11% in EFMA (p = 0.46). Trypanosoma dionisii was the most frequently detected parasite (54%), followed by T. cruzi DTUs TcI and TcIV and Trypanosoma sp., in Neotropical phyllostomid bats (RNMO63 and RNMO56); mixed infections by T. dionisii/T. cruzi TcIII and T. dionisii/T. cruzi TcI were also observed. The T. cruzi DTUs TcI and TcIV are the genotypes currently involved in cases of acute Chagas disease in Brazil, and T. dionisii was recently found in the heart tissue of an infected child. Surprisingly, we also describe for the first time Crithidia mellificae, a putative monoxenous parasite from insects, infecting a vertebrate host in the Americas. Bats from the Atlantic Forest of Rio de Janeiro state harbor a great diversity of trypanosomatids, maintaining trypanosomatid diversity in this sylvatic environment. [ABSTRACT FROM AUTHOR]

Background: A blend of compounds (pentanoic acid, guaiacol, δ-octalactone and geranylacetone) identified in waterbuck (Kobus defassa) body odour referred to as waterbuck repellent compounds (WRC) and a synthetic repellent 4-methylguaiacol have previously been shown to repel tsetse flies from the morsitans group. However, these repellents have not been evaluated on palpalis group tsetse flies. In this study, we evaluated the effect of these repellents on catches of Glossina fuscipes fuscipes (major vector of human sleeping sickness) in biconical traps and on sticky small targets which are visually attractive to palpalis group flies. The attractive devices were baited with different doses and blends of the repellent compounds. We also assessed the effect of removal of individual constituents in the synthetic blend of WRC on catches of G. f. fuscipes. Methodology/Principal findings: The study was conducted in western Kenya on four islands of Lake Victoria namely Big Chamaunga, Small Chamaunga, Manga and Rusinga. The tsetse fly catches from the treatments were modeled using a negative binomial regression to determine their effect on catches. In the presence of WRC and 4-methylguaiacol (released at ≈2 mg/h and ≈1.4 mg/h respectively), catches of G. f. fuscipes were significantly reduced by 33% (P<0.001) and 22% (P<0.001) respectively in biconical traps relative to control. On sticky small targets the reduction in fly catches were approximately 30% (P<0.001) for both 4-methylguiacol and WRC. In subtractive assays, only removal of geranylacetone from WRC significantly increased catches (by 1.8 times; P <0.001) compared to the complete blend of WRC. Conclusions/Significance: We conclude that WRC and 4-methylguaiacol reduce catches of G. f. fuscipes at stationary visually attractive traps and suggest that they may serve as broad spectrum repellents for Glossina species. We recommend further studies to investigate the effects of these compounds on reduction of G. f. fuscipes attracted to human hosts as this may lead to development of new strategies of reducing the prevalence and incidence of sleeping sickness. [ABSTRACT FROM AUTHOR]

Background: The Madagascar National Strategic Plan for Malaria Control 2018 (NSP) outlines malaria control pre-elimination strategies that include detailed goals for mosquito control. Primary surveillance protocols and mosquito control interventions focus on indoor vectors of malaria, while many potential vectors feed and rest outdoors. Here we describe the application of tools that advance our understanding of diversity, host choice, and Plasmodium infection in the Anopheline mosquitoes of the Western Highland Fringe of Madagascar. Methodology/Principal findings: We employed a modified barrier screen trap, the QUadrant Enabled Screen Trap (QUEST), in conjunction with the recently developed multiplex BLOOdmeal Detection Assay for Regional Transmission (BLOODART). We captured a total of 1252 female Anopheles mosquitoes (10 species), all of which were subjected to BLOODART analysis. QUEST collection captured a heterogenous distribution of mosquito density, diversity, host choice, and Plasmodium infection. Concordance between Anopheles morphology and BLOODART species identifications ranged from 93–99%. Mosquito feeding behavior in this collection frequently exhibited multiple blood meal hosts (single host = 53.6%, two hosts = 42.1%, three hosts = 4.3%). The overall percentage of human positive bloodmeals increased between the December 2017 and the April 2018 timepoints (27% to 44%). Plasmodium positivity was frequently observed in the abdomens of vectors considered to be of secondary importance, with an overall prevalence of 6%. Conclusions/Significance: The QUEST was an efficient tool for sampling exophilic Anopheline mosquitoes. Vectors considered to be of secondary importance were commonly found with Plasmodium DNA in their abdomens, indicating a need to account for these species in routine surveillance efforts. Mosquitoes exhibited multiple blood feeding behavior within a gonotrophic cycle, with predominantly non-human hosts in the bloodmeal. Taken together, this complex feeding behavior could enhance the role of multiple Anopheline species in malaria transmission, possibly tempered by zoophilic feeding tendencies. [ABSTRACT FROM AUTHOR]

The prevalence of rheumatic heart disease (RHD) in the Aboriginal population of the Australian Northern Territory is high, and Streptococcus pyogenes skin infections likely contribute to this. A promising candidate S. pyogenes “30mer” vaccine is composed of 30 pharyngitis associated type-specific antigens from the S. pyogenes M protein. Cross opsonisation experiments suggest that 30mer vaccine protection may extend to non-cognate emm types. A new “emm cluster” scheme for classifying M protein is based on the full-length coding sequence, and correlates with functional and immunological properties, and anatomical tropism. Twenty-seven years of research in the Northern Territory has yielded 1810 S. pyogenes isolates with clinical and emm type data. The primary aim was to analyse these data with reference to the emm cluster scheme and cross opsonisation information, to inform estimation of 30mer vaccine efficacy in the Northern Territory. The isolates encompass 101 emm types. Variants of cluster A-C were enriched in throat isolates, and variants of emm cluster D enriched in skin isolates. Throat isolates were enriched for 30mer vaccine cognate emm types in comparison with skin isolates of which only 25% were vaccine emm types. While cross opsonisation data indicates potential for enhancing 30mer vaccine coverage, more than one third of skin isolates were within 38 emm types untested for cross opsonisation. Emm cluster D variants, in particular emm cluster D4, were not only all non-cognate with the vaccine, but were abundant and diverse, and less likely to be cross-opsonisation positive than other emm clusters. Long term persistence of many emm types in the study area was revealed. It was concluded that the 30mer vaccine efficacy in the Northern Territory will likely require both cross protection, and additional measures to elicit immunity against variants of emm cluster D. [ABSTRACT FROM AUTHOR]

Background: Visceral Leishmaniasis in humans presents with fever, anemia, and splenomegaly and can be lethal if not treated. Nevertheless, the majority of Leishmania infantum-infected individuals does not manifest symptoms and remain so provided they are not immunosuppressed. In this work, the performance of different tests was evaluated to detect asymptomatic individuals who were living in Teresina, Piauí state, Brazil, an endemic area for VL. Methodology: L. infantum-specific antibodies were detected by ELISA and two different rapid immunochromatographic (IC) diagnostic tests, Kalazar Detect and OnSite, and parasitic loads were detected by real time PCR [qPCR]. Additionally, we measured levels of the biomarkers monokine induced by IFN-γ (MIG) and IFN-γ-induced protein 10 (IP-10) before and after stimulation of whole blood with soluble Leishmania antigen [SLA]. Principal findings: Kalazar Detect and OnSite detected, respectively, 76% and 64% of patients presenting with active Visceral Leishmaniasis; 50% and 57% of patients remained positive in these tests, respectively, after treatment. Of the healthy participants in the study who were living in the endemic area, only 1.7% were positive with both of the IC tests. On the other hand, reactivity in ELISA tests revealed that 13% of these individuals presented asymptomatic infections; among VL patients, 84% presenting with active disease were reactive in ELISA, and after treatment, 55.5% were seropositive. L. infantum DNA was present in the blood of 37.9% of infected individuals living in the endemic area, while IP-10 and MIG biomarkers were detected in 26.7% of them. The greatest concordance of positivity occurred between ELISA and qPCR. Conclusion: The association of different techniques can detect asymptomatic infections, however, more research is necessary to develop ideal biomarkers that are simple to use in the clinic and in field studies in areas endemic for Visceral Leishmaniasis. [ABSTRACT FROM AUTHOR]

Background: Acute kidney injury (AKI) is a major complication of snake envenoming, but early diagnosis remains problematic. We aimed to investigate the time course of novel renal biomarkers in AKI following Russell’s viper (Daboia russelii) bites. Methodology/Principal findings: We recruited a cohort of patients with definite Russell’s viper envenoming and collected serial blood and urine samples on admission (<4h post-bite), 4-8h, 8-16h, 16-24h, 1 month and 3 months post-bite. AKI stage (1–3) was defined using the Acute Kidney Injury Network criteria. AKI stages (1–3) were defined by the Acute Kidney Injury Network (AKIN) criteria. There were 65 Russell’s viper envenomings and 49 developed AKI: 24 AKIN stage 1, 13 stage 2 and 12 stage 3. There was a significant correlation between venom concentrations and AKI stage (p = 0.007), and between AKI stage and six peak biomarker concentrations. Although most biomarker concentrations were elevated within 8h, no biomarker performed well in diagnosing AKI <4h post-bite. Three biomarkers were superior to serum creatinine (sCr) in predicting AKI (stage 2/3) 4-8h post-bite: serum cystatin C (sCysC) with an area under the receiver operating curve (AUC-ROC), 0.78 (95%CI:0.64–0.93), urine neutrophil gelatinase-associated lipocalin (uNGAL), 0.74 (95%CI:0.59–0.87) and urine clusterin (uClu), 0.81 (95%CI:0.69–0.93). No biomarker was better than sCr after 8h. Six other urine biomarkers urine albumin, urine beta2-microglobulin, urine kidney injury molecule-1, urine cystatin C, urine trefoil factor-3 and urine osteopontin either had minimal elevation, and/or minimal prediction for AKI stage 2/3 (AUC-ROC<0.7). Conclusions/Significance: AKI was common and sometimes severe following Russell’s viper bites. Three biomarkers uClu, uNGAL and sCysC, appeared to become abnormal in AKI earlier than sCr, and may be useful in early identification of envenoming. [ABSTRACT FROM AUTHOR]

Giardia lamblia is a common intestinal parasitic infection that although often acutely asymptomatic, is associated with debilitating chronic intestinal and extra-intestinal sequelae. In previously healthy adults, a primary sporadic Giardia infection can lead to gut dysfunction and fatigue. These symptoms correlate with markers of inflammation that persist well after the infection is cleared. In contrast, in endemic settings, first exposure occurs in children who are frequently malnourished and also co-infected with other enteropathogens. In these children, Giardia rarely causes symptoms and associates with several decreased markers of inflammation. Mechanisms underlying these disparate and potentially enduring outcomes following Giardia infection are not presently well understood. A body of work suggests that the outcome of experimental Giardia infection is influenced by the nutritional status of the host. Here, we explore the consequences of experimental Giardia infection under conditions of protein sufficiency or deficiency on cytokine responses of ex vivo bone marrow derived dendritic cells (BMDCs) to endotoxin stimulation. We show that BMDCs from Giardia- challenged mice on a protein sufficient diet produce more IL-23 when compared to uninfected controls whereas BMDCs from Giardia challenged mice fed a protein deficient diet do not. Further, in vivo co-infection with Giardia attenuates robust IL-23 responses in endotoxin-stimulated BMDCs from protein deficient mice harboring enteroaggregative Escherichia coli. These results suggest that intestinal Giardia infection may have extra-intestinal effects on BMDC inflammatory cytokine production in a diet dependent manner, and that Giardia may influence the severity of the innate immune response to other enteropathogens. This work supports recent findings that intestinal microbial exposure may have lasting influences on systemic inflammatory responses, and may provide better understanding of potential mechanisms of post-infectious sequelae and clinical variation during Giardia and enteropathogen co-infection. [ABSTRACT FROM AUTHOR]

Background: T cell immunoglobulin mucin domain-1 (TIM-1) is a phosphatidylserine (PS) receptor, mediating filovirus entry into cells through interactions with PS on virions. TIM-1 expression has been implicated in Ebola virus (EBOV) pathogenesis; however, it remains unclear whether this is due to TIM-1 serving as a filovirus receptor in vivo or, as others have suggested, TIM-1 induces a cytokine storm elicited by T cell/virion interactions. Here, we use a BSL2 model virus that expresses EBOV glycoprotein to demonstrate the importance of TIM-1 as a virus receptor late during in vivo infection. Methodology/Principal findings: Infectious, GFP-expressing recombinant vesicular stomatitis virus encoding either full length EBOV glycoprotein (EBOV GP/rVSV) or mucin domain deleted EBOV glycoprotein (EBOV GPΔO/rVSV) was used to assess the role of TIM-1 during in vivo infection. GFP-expressing rVSV encoding its native glycoprotein G (G/rVSV) served as a control. TIM-1-sufficient or TIM-1-deficient BALB/c interferon α/β receptor-/- mice were challenged with these viruses. While G/rVSV caused profound morbidity and mortality in both mouse strains, TIM-1-deficient mice had significantly better survival than TIM-1-expressing mice following EBOV GP/rVSV or EBOV GPΔO/rVSV challenge. EBOV GP/rVSV or EBOV GPΔO/rVSV in spleen of infected animals was high and unaffected by expression of TIM-1. However, infectious virus in serum, liver, kidney and adrenal gland was reduced late in infection in the TIM-1-deficient mice, suggesting that virus entry via this receptor contributes to virus load. Consistent with higher virus loads, proinflammatory chemokines trended higher in organs from infected TIM-1-sufficient mice compared to the TIM-1-deficient mice, but proinflammatory cytokines were more modestly affected. To assess the role of T cells in EBOV GP/rVSV pathogenesis, T cells were depleted in TIM-1-sufficient and -deficient mice and the mice were challenged with virus. Depletion of T cells did not alter the pathogenic consequences of virus infection. Conclusions: Our studies provide evidence that at late times during EBOV GP/rVSV infection, TIM-1 increased virus load and associated mortality, consistent with an important role of this receptor in virus entry. This work suggests that inhibitors which block TIM-1/virus interaction may serve as effective antivirals, reducing virus load at late times during EBOV infection. [ABSTRACT FROM AUTHOR]

The definitive method for diagnosis of porcine cysticercosis is the detection of cysticerci at necropsy. Cysts are typically located in the striated muscle and brain. Until recently Taenia solium cysticerci have not been definitively identified in other tissue locations, despite several comprehensive investigations having been undertaken which included investigation of body organs other than muscle and brain. Recently a study conducted in Zambia reported 27% infection with T. solium in the liver of pigs with naturally acquired porcine cysticercosis, as well as some T. solium infection in the lungs and spleen of some animals. We investigated the cause of lesions in sites other than the muscle or brain in a total of 157 pigs from T. solium endemic regions of Uganda and Nepal which were subjected to extensive investigations at necropsy. Lesions which had the potential to be caused by T. solium were characterised by macroscopic and microscopic examination, histology as well as DNA characterisation by PCR-RFLP and sequencing. Lesions were confirmed as being caused by Taenia hydatigena (both viable and non-viable), by T. asiatica and Echinococcus granulosus (in Nepal) and nematode infections. No T. solium-related lesions or cysticerci were identified in any tissue other than muscle and brain. It is recommended that future evaluations of porcine cysticercosis in aberrant tissue locations include DNA analyses that take appropriate care to avoid the possibility of contamination of tissue specimens with DNA from a different tissue location or a different animal. The use of appropriate control samples to confirm the absence of cross-sample contamination is also recommended. [ABSTRACT FROM AUTHOR]

Background: Salmonella enterica serovar Enteritidis is a cause of both poultry- and egg-associated enterocolitis globally and bloodstream-invasive nontyphoidal Salmonella (iNTS) disease in sub-Saharan Africa (sSA). Distinct, multi-drug resistant genotypes associated with iNTS disease in sSA have recently been described, often requiring treatment with fluoroquinolone antibiotics. In industrialised countries, antimicrobial use in poultry production has led to frequent fluoroquinolone resistance amongst globally prevalent enterocolitis-associated lineages. Methodology/Principal findings: Twenty seven S. Enteritidis isolates from patients with iNTS disease and two poultry isolates, collected between 2007 and 2015 in the Ashanti region of Ghana, were whole-genome sequenced. These isolates, notable for a high rate of diminished ciprofloxacin susceptibility (DCS), were placed in the phyletic context of 1,067 sequences from the Public Health England (PHE) S. Enteritidis genome database to understand whether DCS was associated with African or globally-circulating clades of S. Enteritidis. Analysis showed four of the major S. Enteritidis clades were represented, two global and two African. All thirteen DCS isolates, containing a single gyrA mutation at codon 87, belonged to a global PT4-like clade responsible for epidemics of poultry-associated enterocolitis. Apart from two DCS isolates, which clustered with PHE isolates associated with travel to Spain and Brazil, the remaining DCS isolates, including one poultry isolate, belonged to two monophyletic clusters in which gyrA 87 mutations appear to have developed within the region. Conclusions/Significance: Extensive phylogenetic diversity is evident amongst iNTS disease-associated S. Enteritidis in Ghana. Antimicrobial resistance profiles differed by clade, highlighting the challenges of devising empirical sepsis guidelines. The detection of fluoroquinolone resistance in phyletically-related poultry and human isolates is of major concern and surveillance and control measures within the region’s burgeoning poultry industry are required to protect a human population at high risk of iNTS disease. [ABSTRACT FROM AUTHOR]

In French Guiana, cutaneous leishmaniasis is highly endemic, whereas no autochthonous case of visceral leishmaniasis have been reported so far. However, due to its proximity to Brazil which is highly endemic for visceral leishmaniasis, and the high transboundary population flow, an epidemiological challenge could arise at any time. As an overseas department and region and the largest outermost region of the European Union, epidemiological surveillance of visceral leishmaniasis is of great importance. Our study aimed to investigate the presence of Leishmania spp. in domestic (dogs) and sylvatic (bats) animals from French Guiana. Over the 2008–2018 period, samples from 349 animals were collected. They included blood from 179 autochthonous dogs and 59 bats, spleen samples from 33 bats and, blood from 78 military working dogs (MWD) collected before their departure from continental France and at the end of their four-month stay in French Guiana. Samples were screened using real-time polymerase chain reaction (qPCR) assays targeting Leishmania DNA followed by sequencing of 18S rRNA, kDNA and ITS2 genes. L. infantum was detected in 2.3% (8/349) of animals with 1.7% (3/179) of autochthonous dogs, 5.1% (4/78) of MWD returning from French Guiana, whereas they were negative before their departure. One of them dates back to 2012. All these dogs were positive for serological tests. In addition, L. infantum DNA was detectable in one bat spleen sample, belonging to Carollia perspicillata species. We report here for the first time an infection with L. infantum in dogs and bat from French Guiana. Our results suggest the existence of potential reservoir and transmission cycle for visceral leishmaniasis, at least since 2012, which was unknown in this territory until now. Further studies are needed to determine how these animals were infected and which vectors are involved in the transmission in this area. [ABSTRACT FROM AUTHOR]

Background: Strongyloides stercoralis is a neglected soil-transmitted helminth that occurs worldwide, though it is particularly endemic in tropical and subtropical areas. It can cause long-lasting and potentially fatal infections due to its ability to replicate within its host. S. stercoralis causes gastrointestinal and dermatological morbidity. The objective of this study was to assess the S. stercoralis infection risk and, using geostatistical models, to predict its geographical distribution in Cambodia. Methodology / Principal findings: A nation-wide, community-based parasitological survey was conducted among the Cambodian population, aged 6 years and older. S. stercoralis was diagnosed using a serological diagnostic test that detects IgG antibodies in urine. Data on demography, hygiene and knowledge about helminth infection were collected. S. stercoralis prevalence among 7,246 participants with a complete data record was 30.5%, ranging from 10.9% to 48.2% across provinces. The parasite was ubiquitous in Cambodia; only five south-eastern provinces had prevalence rates below 20%. Infection risk increased with age for both men and women, although girls under the age of 13 and women aged 50 years and over had lower odds of infection than their male counterparts. Open defecation was associated with higher odds of infection, while having some knowledge of the health problems caused by worms was a protective factor. Infection risk was positively associated with nighttime maximum temperature, minimum rainfall, and distance to water; it was negatively associated with land occupied by rice fields. Conclusions / Significance: S. stercoralis infection is rampant in Cambodia. Control programs delivering ivermectin are needed to manage the parasite. However, the high cost of this drug in Cambodia currently precludes the implementation of control initiatives. Donations, subsidies or affordable generics are needed so that S. stercoralis, which infects almost a third of the Cambodian population, can be addressed through an adequate control program. [ABSTRACT FROM AUTHOR]

Background: The objectives of this study were to 1) evaluate the influence of treatment with praziquantel on the inflammatory milieu in maternal, placental, and cord blood, 2) assess the extent to which proinflammatory signatures in placental and cord blood impacts birth outcomes, and 3) evaluate the impact of other helminths on the inflammatory micro environment. Methods/Findings: This was a secondary analysis of samples from 369 mother-infant pairs participating in a randomized controlled trial of praziquantel given at 12–16 weeks’ gestation. We performed regression analysis to address our study objectives. In maternal peripheral blood, the concentrations of CXCL8, and TNF receptor I and II decreased from 12 to 32 weeks’ gestation, while IL-13 increased. Praziquantel treatment did not significantly alter the trajectory of the concentration of any of the cytokines examined. Hookworm infection was associated with elevated placental IL-1, CXCL8 and IFN-γ. The risk of small-for-gestational age increased with elevated IL-6, IL-10, and CXCL8 in cord blood. The risk of prematurity was increased when cord blood sTNFRI and placental IL-5 were elevated. Conclusions: Our study suggests that fetal cytokines, which may be related to infectious disease exposures, contribute to poor intrauterine growth. Additionally, hookworm infection influences cytokine concentrations at the maternal-fetal interface. Clinical Trial Registry number and website: ClinicalTrials.gov (). [ABSTRACT FROM AUTHOR]

Background: African trypanosomosis, primarily transmitted by tsetse flies, remains a serious public health and economic challenge in sub-Saharan Africa. Interventions employing natural repellents from non-preferred hosts of tsetse flies represent a promising management approach. Although zebras have been identified as non-preferred hosts of tsetse flies, the basis for this repellency is poorly understood. We hypothesized that zebra skin odors contribute to their avoidance by tsetse flies. Methodology/Principal findings: We evaluated the effect of crude zebra skin odors on catches of wild savannah tsetse flies (Glossina pallidipes Austen, 1903) using unbaited Ngu traps compared to the traps baited with two known tsetse fly management chemicals; a repellent blend derived from waterbuck odor, WRC (comprising geranylacetone, guaiacol, pentanoic acid and δ-octalactone), and an attractant comprising cow urine and acetone, in a series of Latin square-designed experiments. Coupled gas chromatography-electroantennographic detection (GC/EAD) and GC-mass spectrometry (GC/MS) analyses of zebra skin odors identified seven electrophysiologically-active components; 6-methyl-5-hepten-2-one, acetophenone, geranylacetone, heptanal, octanal, nonanal and decanal, which were tested in blends and singly for repellency to tsetse flies when combined with Ngu traps baited with cow urine and acetone in field trials. The crude zebra skin odors and a seven-component blend of the EAD-active components, formulated in their natural ratio of occurrence in zebra skin odor, significantly reduced catches of G. pallidipesby 66.7% and 48.9% respectively, and compared favorably with the repellency of WRC (58.1%– 59.2%). Repellency of the seven-component blend was attributed to the presence of the three ketones 6-methyl-5-hepten-2-one, acetophenone and geranylacetone, which when in a blend caused a 62.7% reduction in trap catch of G. pallidipes. Conclusions/Significance: Our findings reveal fundamental insights into tsetse fly ecology and the allomonal effect of zebra skin odor, and potential integration of the three-component ketone blend into the management toolkit for tsetse and African trypanosomosis control. [ABSTRACT FROM AUTHOR]

The importance of Zika virus (ZIKV) has increased noticeably since the outbreak in the Americas in 2015, when the illness was associated with congenital disorders. Although there is evidence of sexual transmission of the virus, the mosquito Aedes aegypti is believed to be the main vector for transmission to humans. This species of mosquito has not only been found naturally infected with ZIKV, but also has been the subject of study in many vector competence assays that employ different strains of ZIKV around the world. In Argentina, the first case was reported in February 2016 and a total of 278 autochthonous cases have since been confirmed, however, ZIKV virus has not been isolated from any mosquito species yet in Argentina. In order to elucidate if Argentinian Ae. aegypti populations could be a possible vector of ZIKV, we conducted vector competence studies that involved a local strain of ZIKV from Chaco province, and a Venezuelan strain obtained from an imported case. For this purpose, Ae. aegypti adults from the temperate area of Argentina (Buenos Aires province) were fed with infected blood. Body, legs and saliva were harvested and tested by plaque titration on plates of Vero cells for ZIKV at 7, 11 and 14 days post infection (DPI) in order to calculate infection, transmission, and dissemination rates, respectively. Both strains were able to infect mosquitoes at all DPIs, whereas dissemination and transmission were observed at all DPIs for the Argentinian strain but only at 14 DPI for the Venezuelan strain. This study proves the ability of Ae. aegypti mosquitoes from Argentina to become infected with two different strains of ZIKV, both belonging to the Asian lineage, and that the virus can disseminate to the legs and salivary glands. [ABSTRACT FROM AUTHOR]

Concomitant infection with human immunodeficiency virus (HIV) and the Leishmania parasite is a growing public health problem, the result of the former spreading to areas where the latter is endemic. Leishmania infection is usually asymptomatic in immunocompetent individuals, but the proportion of HIV+ individuals in contact with the parasite who remain asymptomatic is not known. The aim of the present work was to examine the use of cytokine release assays in the detection of asymptomatic immune responders to Leishmania among HIV+ patients with no previous leishmaniasis or current symptomatology. Eighty two HIV+ patients (all from Fuenlabrada, Madrid, Spain, where a leishmaniasis outbreak occurred in 2009) were examined for Leishmania infantum infection using molecular and humoral response-based methods. None returned a positive molecular or serological result for the parasite. Thirteen subjects showed a positive lymphoproliferative response to soluble Leishmania antigen (SLA), although the mean CD4+ T lymphocyte counts of these patients was below the normal range. Stimulation of peripheral blood mononuclear cells (PBMC) or whole blood with SLA (the lymphoproliferative assay and whole blood assay respectively), led to the production of specific cytokines and chemokines. Thus, despite being immunocompromised, HIV+ patients can maintain a Th1-type cellular response to Leishmania. In addition, cytokine release assays would appear to be useful tools for detecting these individuals via the identification of IFN-γ in the supernatants of SLA-stimulated PBMC, and of IFN-γ, MIG and IL-2 in SLA-stimulated whole blood. These biomarkers appear to be 100% reliable for detecting asymptomatic immune responders to Leishmania among HIV+ patients. [ABSTRACT FROM AUTHOR]

Detection and sequencing of chikungunya virus (CHIKV) genome was performed using a combination of a modified reverse transcription loop-mediated isothermal amplification (RT-LAMP) method and a MinION sequencer. We developed the protocol for drying all the reagents for the RT-LAMP in a single reaction tube. Using this system, the CHIKV genome was effectively amplified under isothermal conditions, and used as a template for MinION sequencing with a laptop computer. Our in-house RT-LAMP method and MinION sequencing system were also validated with RNAs and serum samples from recent outbreaks of CHIKV patients in Brazil. The obtained sequence data confirmed the CHIKV outbreaks and identified the genotype. In summary, our established inexpensive on-site genome detection and sequencing system is applicable for both diagnosis of CHIKV infected patients and genotyping of the CHIKV virus in future outbreak in remote areas. [ABSTRACT FROM AUTHOR]

Oral cholera vaccines (OCVs) are being increasingly employed, but current killed formulations generally require multiple doses and lack efficacy in young children. We recently developed a new live-attenuated OCV candidate (HaitiV) derived from a Vibrio cholerae strain isolated during the 2010 Haiti cholera epidemic. HaitiV exhibited an unexpected probiotic-like activity in infant rabbits, preventing intestinal colonization and disease by wild-type V. cholerae before the onset of adaptive immunity. However, it remained unknown whether HaitiV would behave similarly to other OCVs to stimulate adaptive immunity against V. cholerae. Here, we orally immunized adult germ-free female mice to test HaitiV’s immunogenicity. HaitiV safely and stably colonized vaccinated mice and induced known adaptive immune correlates of cholera protection within 14 days of administration. Pups born to immunized mice were protected against lethal challenges of both homologous and heterologous V. cholerae strains. Cross-fostering experiments revealed that protection was not dependent on vaccine colonization in or transmission to the pups. These findings demonstrate the protective immunogenicity of HaitiV and support its development as a new tool for limiting cholera. [ABSTRACT FROM AUTHOR]

Background: The liver fluke Opisthorchis viverrini infects several million people in Southeast Asia. Adult flukes live in the bile ducts of humans, where they cause hepatobiliary pathology, including cholangiocarcinoma. Here, we investigated the potential of extracellular vesicles (EVs) secreted by the fluke and defined recombinant proteins derived from EVs to generate protective immunity in a hamster vaccination-challenge model. Methodology/Principal findings: EVs isolated from the excretory-secretory products of O. viverrini and two recombinant EV surface proteins encoding the large extracellular loops (LEL) of Ov-TSP-2 (rOv-TSP-2) and Ov-TSP-3 (rOv-TSP-3) were adjuvanted and used to vaccinate hamsters intraperitoneally followed by challenge infection with O. viverrini metacercariae. The number of adult flukes recovered from hamsters immunized with EVs, rOv-TSP-2, rOv-TSP-3 and rOv-TSP-2+rOv-TSP-3 were significantly reduced compared to control animals vaccinated with adjuvant alone. The number of eggs per gram feces was also significantly reduced in hamsters vaccinated with rOv-TSP-2 compared to controls, but no significant differences were found in the other groups. The average length of worms recovered from hamsters vaccinated with EVs, rOv-TSP-2 and rOv-TSP-3 was significantly shorter than that of worms recovered from the control group. Anti-EV IgG levels in serum and bile were significantly higher in hamsters vaccinated with EVs compared to control hamsters both pre- and post-challenge. In addition, levels of anti-rOv-TSP antibodies in the serum and bile were significantly higher than control hamsters both pre- and post-challenge. Finally, antibodies against rOv-TSP-2 and rOv-TSP-3 blocked uptake of EVs by human primary cholangiocyte in vitro, providing a plausible mechanism by which these vaccines exert partial efficacy and reduce the intensity of O. viverrini infection. Conclusion/Significance: Liver fluke EVs and recombinant tetraspanins derived from the EV surface when administered to hamsters induce antibody responses that block EV uptake by target bile duct cells and exert partial efficacy and against O. viverrini challenge. [ABSTRACT FROM AUTHOR]

Despite worldwide mass drug administration, it is estimated that 68 million individuals are still infected with lymphatic filariasis with 19 million hydrocele and 17 million lymphedema reported cases. Despite the staggering number of pathology cases, the majority of LF-infected individuals do not develop clinical symptoms and present a tightly regulated immune system characterized by higher frequencies of regulatory T cells (Treg), suppressed proliferation and Th2 cytokine responses accompanied with increased secretion of IL-10, TGF-β and infection-specific IgG4. Nevertheless, the filarial-induced modulation of the host`s immune system and especially the role of regulatory immune cells like regulatory B (Breg) and Treg during an ongoing LF infection remains unknown. Thus, we analysed Breg and Treg frequencies in peripheral blood from Ghanaian uninfected endemic normals (EN), lymphedema (LE), asymptomatic patent (CFA+MF+) and latent (CFA+MF-) W. bancrofti-infected individuals as well as individuals who were previously infected with W. bancrofti (PI) but had cleared the infection due to the administration of ivermectin (IVM) and albendazole (ALB). In summary, we observed that IL-10-producing CD19+CD24highCD38dhigh Breg were specifically increased in patently infected (CFA+MF+) individuals. In addition, CD19+CD24highCD5+CD1dhigh and CD19+CD5+CD1dhighIL-10+ Breg as well as CD4+CD127-FOXP3+ Treg frequencies were significantly increased in both W. bancrofti-infected cohorts (CFA+MF+ and CFA+MF-). Interestingly, the PI cohort presented frequency levels of all studied regulatory immune cell populations comparable with the EN group. In conclusion, the results from this study show that an ongoing W. bancrofti infection induces distinct Breg and Treg populations in peripheral blood from Ghanaian volunteers. Those regulatory immune cell populations might contribute to the regulated state of the host immune system and are probably important for the survival and fertility (microfilaria release) of the helminth. [ABSTRACT FROM AUTHOR]

Background: A single co-administered dose of ivermectin (IVM) plus diethylcarbamazine (DEC) plus albendazole (ALB), or triple-drug therapy, was recently found to be more effective for clearing microfilariae (Mf) than standard DEC plus ALB currently used for mass drug administration programs for lymphatic filariasis (LF) outside of sub-Saharan Africa. Triple-drug therapy has not been previously tested in LF-uninfected individuals from Africa. This study evaluated the pharmacokinetics (PK), safety, and efficacy of triple-drug therapy in people with and without Wuchereria bancrofti infection in West Africa. Methods: In this open-label cohort study, treatment-naïve microfilaremic (>50 mf/mL, n = 32) and uninfected (circulating filarial antigen negative, n = 24) adults residing in Agboville district, Côte d’Ivoire, were treated with a single dose of IVM plus DEC plus ALB, and evaluated for adverse events (AEs) until 7 days post treatment. Drug levels were assessed by liquid chromatography and mass spectrometry. Persons responsible for assessing AEs were blinded to participants’ infection status. Findings: There was no difference in AUC0-inf or Cmax between LF-infected and uninfected participants (P>0.05 for all comparisons). All subjects experienced mild AEs; 28% and 25% of infected and uninfected participants experienced grade 2 AEs, respectively. There were no severe or serious adverse events. Only fever (16 of 32 versus 4 of 24, P<0.001) and scrotal pain/swelling in males (6 of 20 versus 0 of 12, P = 0.025) were more frequent in infected than uninfected participants. All LF positive participants were amicrofilaremic at 7 days post-treatment and 27 of 31 (87%) remained amicrofilaremic 12 months after treatment. Conclusions: Moderate to heavy W. bancrofti infection did not affect PK parameters for IVM, DEC or ALB following a single co-administered dose of these drugs compared to uninfected individuals. The drugs were well tolerated. This study confirmed the efficacy of the triple-drug therapy for clearing W. bancrofti Mf and has added important information to support the use of this regimen in LF elimination programs in areas of Africa without co-endemic onchocerciasis or loiasis. Trial registration: ClinicalTrials.gov . [ABSTRACT FROM AUTHOR]

Background: Wolbachia’s ability to restrict arbovirus transmission makes it a promising tool to combat mosquito-transmitted diseases. Wolbachia-infected Aedes aegypti are currently being released in locations such as Brazil, which regularly experience concurrent outbreaks of different arboviruses. A. aegypti can become co-infected with, and transmit multiple arboviruses with one bite, which can complicate patient diagnosis and treatment. Methodology/principle findings: Using experimental oral infection of A. aegypti and then RT-qPCR, we examined ZIKV/DENV-1 and ZIKV/DENV-3 co-infection in Wolbachia-infected A. aegypti and observed that Wolbachia-infected mosquitoes experienced lower prevalence of infection and viral load than wildtype mosquitoes, even with an extra infecting virus. Critically, ZIKV/DENV co-infection had no significant impact on Wolbachia’s ability to reduce viral transmission. Wolbachia infection also strongly altered expression levels of key immune genes Defensin C and Transferrin 1, in a virus-dependent manner. Conclusions/significance: Our results suggest that pathogen interference in Wolbachia-infected A. aegypti is not adversely affected by ZIKV/DENV co-infection, which suggests that Wolbachia-infected A. aegypti will likely prove suitable for controlling mosquito-borne diseases in environments with complex patterns of arbovirus transmission. [ABSTRACT FROM AUTHOR]