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Mass drug administration (MDA) is a proven strategy for lymphatic filariasis, onchocerciasis, blinding trachoma, soil-transmitted helminths, and schistosomiasis control programs. By providing regular MDA to at-risk populations, infection levels of these neglected tropical diseases (NTDs) can be reduced to a point where the force of transmission is reduced and morbidity is moderated.1 Because the treatments used are safe for uninfected individuals, in most settings, the program expenditures for providing MDA to the whole at-risk population are more cost effective than diagnosing and treating each infected individual. The programs for different NTDs are at various stages of maturation. Whereas lymphatic filariasis and blinding trachoma have fairly well-defined strategies for where to initiate MDA, how to track progress, and when treatment can be stopped,2,3 other programs such as schistosomiasis control still have important operational research questions that require attention. This is in part due to the longer time that donated drugs used for treating lymphatic filariasis (ivermectin and albendazole) and trachoma (azithromycin) have been available. However, in recent years, generous donations from pharmaceutical companies, governmental bodies, and private foundations have made it possible to begin widespread MDA for schistosomiasis using praziquantel. In part to address the unanswered questions about best methods for schistosomiasis control, the Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) was formed.4 A primary goal of SCORE has been to identify the most effective strategies for reducing prevalence and intensity of schistosome infections in endemic areas with different initial prevalence of Schistosoma mansoni or Schistosoma haematobium through randomized trials to compare MDA frequency and target population. We conducted one of the SCORE studies in 150 villages in western Kenya with high baseline prevalence (> 25%) of S. mansoni. Over a 5-year period, we compared the impact of MDA provided at the community or school level either annually or with intervening years. Assessments of infection prevalence and intensity in children aged 9–12 years were performed at baseline, each year MDA was provided, and a final evaluation was conducted. The studies focused on school-aged children (SAC) because this is the age-group that typically has the highest infection levels. In addition, infection levels in community adults and first-year students were assessed at baseline and the final evaluation to determine what effect MDA may have on infection levels in the larger community.

Background Recent research suggests that schistosomiasis targets for morbidity control and elimination as a public health problem could benefit from a reanalysis. These analyses would define evidence-based targets that control programs could use to confidently assert that they had controlled or eliminated schistosomiasis as a public health problem. We estimated how low Schistosoma haematobium infection levels diagnosed by urine filtration in school-age children should be decreased so that microhematuria prevalence was at, or below, a “background” level of morbidity. Methodology Data obtained from school-age children in Burkina Faso, Mali, Niger, Tanzania, and Zambia who participated in schistosomiasis monitoring and evaluation cohorts were reanalyzed before and after initiation of preventive chemotherapy. Bayesian models estimated the infection level prevalence probabilities associated with microhematuria thresholds ≤10%, 13%, or 15%. Principal findings An infection prevalence of 5% could be a sensible target for urogenital schistosomiasis morbidity control in children as microhematuria prevalence was highly likely to be below 10% in all surveys. Targets of 8% and 11% infection prevalence were highly likely to result in microhematuria levels less than 13% and 15%, respectively. By contrast, measuring heavy-intensity infections only achieves these thresholds at impractically low prevalence levels. Conclusions/significance A target of 5%, 8%, or 11% urogenital schistosomiasis infection prevalence in school-age children could be used to determine whether a geographic area has controlled or eliminated schistosomiasis as a public health problem depending on the local background threshold of microhematuria., Author summary For urogenital schistosomiasis, targets for morbidity control and elimination as a public health problem are based on the percentage of school-age children with a heavy intensity infection in a set of sentinel schools. These targets are not tied to specific morbidity indicators and should be reevaluated due to the recognition that all infections have an impact on people’s health. Multiple studies have shown a strong association between urogenital schistosomiasis infection and microhematuria. In these analyses, data from children aged 6–15 years in monitoring and evaluation cohorts from five African countries were used to determine whether infection and heavy intensity infection targets could be developed, based on a prevalence of microhematuria in a school without schistosomiasis infections before and after initiation of a deworming program. Results indicate that targets of 5%, 8%, or 11% urogenital schistosomiasis infection prevalence in school-age children can be used to reliably conclude that a school is below a microhematuria prevalence of 10%, 13%, or 15%, respectively. These targets could be used by control program managers as guide to determine whether morbidity has been controlled or eliminated as a public health problem.

BackgroundTrichomonas vaginalis virus (TVV) is a non-segmented, 4.5–5.5 kilo-base pair (kbp), double-stranded RNA virus infecting T. vaginalis. The objectives of this study were to examine the TVV prevalence in US Trichomonas vaginalis isolates and TVV’s associations with patient demographics, clinical outcomes, and metronidazole resistance.MethodsArchived T. vaginalis isolates from the enrollment visits of 355 women participating in a T. vaginalis treatment trial in Birmingham, Alabama, were thawed and grown in culture. Their total RNA was extracted using a Trizol reagent. Contaminating, single-stranded RNA was precipitated using 4.0 M Lithium Chloride and centrifugation. The samples were analyzed by gel electrophoresis to visualize a 4.5 kbp band representative of TVV. In vitro testing for metronidazole resistance was also performed on 25/47 isolates obtained from the women’s test of cure visits.ResultsTVV was detected in 142/355 (40%) isolates at the enrollment visit. Women with TVV-positive (TVV+) isolates were significantly older (P = .01), more likely to smoke (P = .04), and less likely to report a history of gonorrhea (P = .04). There was no association between the presence of clinical symptoms or repeat T. vaginalis infections with TVV+ isolates (P = .14 and P = .44, respectively). Of 25 test of cure isolates tested for metronidazole resistance, 0/10 TVV+ isolates demonstrated resistance, while 2/15 TVV-negative isolates demonstrated mild to moderate resistance (P = .23).ConclusionsOf 355 T. vaginalis isolates tested for TVV, T. vaginalis isolates tested for TVV, the prevalence was 40%. However, there was no association of TVV+ isolates with clinical symptoms, repeat infections, or metronidazole resistance. These results suggest that TVV may be commensal to T. vaginalis.

Background Current World Health Organization guidelines utilize prevalence of heavy-intensity infections (PHIs), that is, ≥50 eggs per 10 mL of urine for Schistosoma haematobium and ≥400 eggs per gram of stool for S. mansoni, to determine whether a targeted area has controlled schistosomiasis morbidity or eliminated schistosomiasis as a public health problem. The relationship between these PHI categories and morbidity is not well understood. Methods School-age participants enrolled in schistosomiasis monitoring and evaluation cohorts from 2003 to 2008 in Burkina Faso, Mali, Niger, Tanzania, Uganda, and Zambia were surveyed for infection and morbidity at baseline and after 1 and 2 rounds of preventive chemotherapy. Logistic regression was used to compare morbidity prevalence among participants based on their school’s PHI category. Results Microhematuria levels were associated with the S. haematobium PHI categories at all 3 time points. For any other S. haematobium or S. mansoni morbidity that was measured, PHI categories did not differentiate morbidity prevalence levels consistently. Conclusions These analyses suggest that current PHI categorizations do not differentiate the prevalence of standard morbidity markers. A reevaluation of the criteria for schistosomiasis control is warranted.

Background World Health Organization (WHO) guidelines for measuring global progress in schistosomiasis control classify individuals with Schistosoma spp. infections based on the concentration of excreted eggs. We assessed the associations between WHO infection intensity categories and morbidity prevalence for selected S. haematobium and S. mansoni morbidities in school-age children. Methodology A total of 22,488 children aged 6–15 years from monitoring and evaluation cohorts in Burkina Faso, Mali, Niger, Uganda, Tanzania, and Zambia from 2003–2008 were analyzed using Bayesian logistic regression. Models were utilized to evaluate associations between intensity categories and the prevalence of any urinary bladder lesion, any upper urinary tract lesion, microhematuria, and pain while urinating (for S. haematobium) and irregular hepatic ultrasound image pattern (C-F), enlarged portal vein, laboratory-confirmed diarrhea, and self-reported diarrhea (for S. mansoni) across participants with infection and morbidity data. Principal findings S. haematobium infection intensity categories possessed consistent morbidity prevalence across surveys for multiple morbidities and participants with light infections had elevated morbidity levels, compared to negative participants. Conversely, S. mansoni infection intensity categories lacked association with prevalence of the morbidity measures assessed. Conclusions/significance Current status infection intensity categories for S. haematobium were associated with morbidity levels in school-age children, suggesting urogenital schistosomiasis morbidity can be predicted by an individual’s intensity category. Conversely, S. mansoni infection intensity categories were not consistently indicative of childhood morbidity at baseline or during the first two years of a preventive chemotherapy control program., Author summary Infections with Schistosoma parasites are commonly classified by the presence and concentration of excreted Schistosoma eggs. Guidelines put forward by the World Health Organization (WHO) include classifications of S. haematobium infections assessed by urine filtration into light and heavy infections and S. mansoni infections assessed by Kato-Katz thick smears into light, moderate, and heavy infections. Past evidence has demonstrated an association between intensity of infection with morbidity for severe morbidities, but this was before recognition of the effect of light-intensity infections on morbidity and was done in treatment naïve populations. In these analyses, we assessed the associations between the WHO classifications for infection intensity and a wide array of S. haematobium and S. mansoni morbidity indicators in school-age children ascertained in monitoring and evaluation cohorts before and after initiation of deworming. Our analyses found a high correlation with S. haematobium intensity categories and morbidity indicators, especially microhematuria, but weaker correlation between S. mansoni intensity categories and morbidity indicators. The results indicate that, on the aggregate, the intensity categories represent a person’s S. haematobium-related morbidity but are poor at representing a person’s S. mansoni-related morbidity.

BackgroundTrichomonas vaginalisis the most common non-viral sexually transmitted infection. 5-Nitroimidazoles [metronidazole (MTZ) and tinidazole (TDZ)] are FDA-approved treatments. To better understand treatment failure, we conducted a systematic review on mechanisms of 5-nitroimidazole resistance.MethodsPubMed, ScienceDirect and EMBASE databases were searched using keywordsTrichomonas vaginalis, trichomoniasis, 5-nitroimidazole, metronidazole, tinidazole and drug resistance. Non-English language articles and articles on other treatments were excluded.ResultsThe search yielded 606 articles, of which 550 were excluded, leaving 58 articles.Trichomonas vaginalisresistance varies and is higher with MTZ (2.2–9.6%) than TDZ (0–2%). Resistance can be aerobic or anaerobic and is relative rather than absolute. Differential expression of enzymes involved in trichomonad energy production and antioxidant defenses affects 5-nitroimidazole drug activation; reduced expression of pyruvate:ferredoxin oxidoreductase, ferredoxin, nitroreductase, hydrogenase, thioredoxin reductase and flavin reductase are implicated in drug resistance.Trichomonas vaginalisinfection withMycoplasma hominisorT. vaginalisvirus has also been associated with resistance.Trichomonas vaginalishas two genotypes, with greater resistance seen in type 2 (vstype 1) populations.Discussion5-Nitroimidazole resistance results from differential expression of enzymes involved in energy production or antioxidant defenses, along with genetic mutations in theT. vaginalisgenome. Alternative treatments outside of the 5-nitroimidazole class are needed.

Introduction Globally, schistosomes infect approximately 200 million people, with 90% of infections in sub‐Saharan Africa. Schistosomiasis is hypothesized to increase HIV‐1 acquisition risk, and multiple cross‐sectional studies reported strong associations. We evaluated this hypothesis within four large prospective cohorts. Methods We conducted nested case‐control analyses within three longitudinal cohorts of heterosexual HIV‐1 serodiscordant couples and one female sex worker (FSW) cohort from Kenya and Uganda. The serodiscordant couples studies were conducted between 2004 and 2012 while the FSW cohort analysis included participant follow‐up from 1993 to 2014. Cases HIV‐1 seroconverted during prospective follow‐up; three controls were selected per case. The presence of circulating anodic antigen in archived serum, collected prior to HIV‐1 seroconversion, identified participants with active schistosomiasis; immunoblots determined the schistosome species. Data from serodiscordant couples cohorts were pooled, while the FSW cohort was analysed separately to permit appropriate confounder adjustment. Results We included 245 HIV‐1 seroconverters and 713 controls from the serodiscordant couples cohorts and 330 HIV‐1 seroconverters and 962 controls from the FSW cohort. The prevalence of active schistosomiasis was 20% among serodiscordant couples and 22% among FSWs. We found no association between schistosomiasis and HIV‐1 acquisition risk among males (adjusted odds ratio (aOR) = 0.99, 95% CI 0.59 to 1.67) or females (aOR = 1.21, 95% CI 0.64 to 2.30) in serodiscordant couples. Similarly, in the FSW cohort we detected no association (adjusted incidence rate ratio (aIRR) = 1.11, 95% CI 0.83 to 1.50). Exploring schistosome species‐specific effects, there was no statistically significant association between HIV‐1 acquisition risk and Schistosoma mansoni (serodiscordant couples: aOR = 0.90, 95% CI 0.56 to 1.44; FSW: aIRR = 0.83, 95% CI 0.53 to 1.20) or Schistosoma haematobium (serodiscordant couples: aOR = 1.06, 95% CI 0.46 to 2.40; FSW: aIRR = 1.64, 95% CI 0.93 to 2.87) infection. Conclusions Schistosomiasis was not a strong risk factor for HIV‐1 acquisition in these four prospective studies. S. mansoni was responsible for the majority of schistosomiasis in these cohorts, and our results do not support the hypothesis that S. mansoni infection is associated with increased HIV‐1 acquisition risk. S. haematobium infection was associated with a point estimate of elevated HIV‐1 risk in the FSW cohort that was not statistically significant, and there was no trend towards a positive association in the serodiscordant couples cohorts.

Background Many regions of sub-Saharan Africa experience a high prevalence of both schistosomiasis and HIV-1, leading to frequent coinfection. Higher plasma HIV-1 viral loads are associated with faster disease progression and genital HIV-1 loads are a primary determinant of HIV-1 transmission risk. We hypothesized that schistosome infection would be associated with higher HIV-1 viral loads in plasma and genital samples. Methods/Principal findings We utilized data from individuals who HIV-1 seroconverted while enrolled in one of four prospective cohort studies. Plasma and genital viral loads collected 4–24 months after the estimated date of HIV-1 acquisition, but prior to antiretroviral therapy initiation, were included. Detection of circulating anodic antigen in archived blood samples, collected prior to HIV-1 seroconversion, identified participants with active schistosomiasis; immunoblots determined the schistosome species causing infection. Our analysis included 370 HIV-1 seroconverters with plasma viral load results, of whom 82 (22%) had schistosomiasis. We did not find a statistically significant association between schistosomiasis and higher HIV-1 set point plasma viral loads (-0.17 log10 copies/ml, 95% CI -0.38 to 0.03); S. mansoni infection was associated with a lower set point (-0.34 log10 copies/ml, 95% CI -0.58 to -0.09). We found no association between schistosomiasis and cervical (+0.07 log10 copies/swab, 95% CI -0.20 to 0.34) or vaginal (+0.11 log10 copies/swab, 95% CI -0.17 to 0.39) set point viral loads; S. haematobium infection was associated with lower cervical viral loads (-0.59 log10 copies/swab, 95% CI -1.11 to -0.06). Conclusions/Significance These results do not support the hypotheses that schistosome coinfection increases plasma or genital HIV-1 viral loads., Author summary Schistosomiasis is a parasitic disease that is common in many parts of sub-Saharan Africa most affected by the HIV-1 epidemic. Schistosomiasis causes genital damage when schistosome ova become lodged in the female genital tract, inducing inflammation that may elevate HIV-1 genital viral loads and increase the risk of HIV-1 transmission. Schistosomiasis may also promote viral replication by facilitating cell-to-cell transmission of HIV-1, elevating HIV-1 plasma viral load levels. Using data from 370 individuals residing in Kenya or Uganda who acquired HIV-1 while participating in one of four prospective cohort studies, we tested the hypotheses that schistosomiasis increases plasma and genital viral load levels. We found no evidence that individuals with schistosomiasis had higher set point plasma viral load levels, a measure of viral replication obtained during the set point period 4–24 months after HIV-1 acquisition when viral load levels remain relatively stable. Additionally, we found no evidence that schistosomiasis was associated with higher female set point genital viral loads measured from vaginal or cervical swabs. Unexpectedly, we found that S. mansoni infection was associated with a decline in plasma viral load levels while S. haematobium infection was associated with a decline in cervical viral load levels. Thus, our results do not support the hypotheses that schistosomiasis increases plasma and genital HIV-1 viral loads.

Immunoregulation is considered a common feature of Schistosoma mansoni infections, and elevated levels of T regulatory (Treg) lymphocytes have been reported during chronic human schistosomiasis. We now report that the removal of Treg (CD4+/CD25hi/CD127low lymphocytes) from peripheral blood mononuclear cells (PBMCs) of S. mansoni–infected individuals leads to increased levels of phytohemagglutinin (PHA)-stimulated interferon gamma (IFNγ) production and decreased interleukin-10 (IL-10) responses. Exposure to schistosome antigens did not result in measurable IFNγ by either PBMC or Treg-depleted populations. Interleukin-10 responses to soluble egg antigens (SEA) by PBMC were unchanged by Treg depletion, but the depletion of Treg greatly decreased IL-10 production to soluble worm antigenic preparation (SWAP). Proliferative responses to PHA increased upon Treg removal, but responses to SEA or SWAP did not, unless only initially low responders were evaluated. Addition of anti-IL-10 increased PBMC proliferative responses to either SEA or SWAP, but did not alter responses by Treg-depleted cells. Blockade by anti-transforming growth factor-beta (TGF-β) increased SEA but not SWAP proliferative responses by PBMC, whereas anti-TGF-β increased both SEA- and SWAP-stimulated responses by Treg-depleted cultures. Addition of both anti-IL-10 and anti-TGF-β to PBMC or Treg-depleted populations increased proliferation of both populations to either SEA or SWAP. These studies demonstrate that Treg appear to produce much of the antigen-stimulated IL-10, but other cell types or subsets of Treg may produce much of the TGF-β. The elevated levels of Treg seen in chronic schistosomiasis appear functional and involve IL-10 and TGF-β in antigen-specific immunoregulation perhaps leading to regulation of immunopathology and/or possibly decreased immunoprotective responses.

Schistosomiasis control programs are designed to reduce morbidity by providing mass drug administration (MDA) of praziquantel to at-risk populations. We compared morbidity markers between two cohorts of Kenyan schoolchildren that initially had high prevalence of Schistosoma mansoni infections. One cohort (N = 416 at year 1) received four rounds of annual MDA in a community-wide treatment (CWT) strategy. The other cohort (N = 386 at year 1) received school-based treatment (SBT) every other year over the 4-year period. We measured infection with S. mansoni and soil-transmitted helminths (STH) as well as subtle morbidity markers at year 1, year 3, and year 5 and compared cohorts with mixed models after controlling for age and gender. At year 5, neither overall S. mansoni prevalence nor the prevalence of high infection–intensity S. mansoni infection was significantly reduced compared with baseline in either the CWT cohort (N = 277 remaining) or the SBT cohort (N = 235 remaining). Nevertheless, by year 5, children in both cohorts demonstrated significant decreases in wasting, ultrasound-detected organomegaly, and STH infection along with significantly improved pediatric quality-of-life scores compared with year 1. Stunting did not change over time, but children who were S. mansoni egg–positive at year 5 had significantly more stunting than children without schistosomiasis. The only significant difference between arms at year 5 was a lower prevalence of STH infections in the CWT group.

Schistosomiasis remains a major public health problem in Kenya. The World Health Organization recommends preventive chemotherapy with praziquantel (PZQ) to control morbidity due to schistosomiasis. Morbidity is considered linked to intensity of infection, which along with prevalence is used to determine the frequency of mass drug administration (MDA) to school-age children. We determined the impact of annual school-based MDA on children across all primary and high school years using a repeated cross-sectional study design in five schools near Lake Victoria in western Kenya, an area endemic for Schistosoma mansoni. At baseline and for the following four consecutive years, between 897 and 1,440 school children in Grades 1–12 were enrolled and evaluated by Kato-Katz for S. mansoni and soil-transmitted helminths (STH), followed by annual MDA with PZQ and albendazole. Four annual rounds of MDA with PZQ were associated with reduced S. mansoni prevalence in all school children (44.7–14.0%; P < 0.001) and mean intensity of infection by 91% (90.4 to 8.1 eggs per gram [epg] of stool; P < 0.001). Prevalence of high-intensity infection (≥ 400 epg) decreased from 6.8% at baseline to 0.3% by the end of the study. Soil-transmitted helminth infections, already low at baseline, also decreased significantly over the years. In this high prevalence area, annual school-based MDA with high coverage across all Grades (1–12) resulted in rapid and progressive declines in overall prevalence and intensity of infection. This decrease was dramatic in regard to heavy infections in older school-attending children.

World Health Organization recommendations for the timing and target population for mass drug administration (MDA) for schistosomiasis are based on the prevalence of infection in school children within a given community. In a large study comparing MDA approaches for Schistosoma mansoni control, we evaluated whether prevalence of infection and egg burdens in 9- to 12-year-old students reflected infection levels in young children and adults in the same community. Cross-sectional surveys of preadolescents (9–12 years old) were compared with those of first year students (5–8 years old) in 225 villages and adults (20–55 years old) in 150 villages along the Kenyan shores of Lake Victoria. Village schistosomiasis prevalence and intensity levels in preadolescents strongly correlated (P < 0.0001) with prevalence and infection intensity for other age groups in the community. Our findings suggest that S. mansoni prevalence and intensity among 9- to 12-year-olds are valid for community sampling purposes in mapping for MDAs.

Parasitologic surveys of young adults in college and university settings are not commonly done, even in areas known to be endemic for schistosomiasis and soil-transmitted helminths. We have done a survey of 291 students and staff at the Kisumu National Polytechnic in Kisumu, Kenya, using the stool microscopy Kato-Katz (KK) method and the urine point-of-care circulating cathodic antigen (POC-CCA) test. Based on three stools/two KK slides each, in the 208 participants for whom three consecutive stools were obtained, Schistosoma mansoni prevalence was 17.8%. When all 291 individuals were analyzed based on the first stool, as done by the national neglected tropical disease (NTD) program, and one urine POC-CCA assay (n = 276), the prevalence was 13.7% by KK and 23.2% by POC-CCA. Based on three stools, 2.5% of 208 participants had heavy S. mansoni infections (≥400 eggs/gram feces), with heavy S. mansoni infections making up 13.5% of the S. mansoni cases. The prevalence of the soil-transmitted helminths (STH: Ascaris lumbricoides, Trichuris trichiura and hookworm) by three stools was 1.4%, 3.1%, and 4.1%, respectively, and by the first stool was 1.4%, 2.4% and 1.4%, respectively. This prevalence and intensity of infection with S. mansoni in a college setting warrants mass drug administration with praziquantel. This population of young adults is ‘in school’ and is both approachable and worthy of inclusion in national schistosomiasis control and elimination programs.

Because anemia is one of the markers of morbidity associated with schistosomiasis, it has been proposed as a potential measure to evaluate the impact of control programs. However, anemia is also a common consequence of malaria, and schistosomiasis and malaria are often co-endemic. To estimate the attributable fraction of anemia due to Schistosoma mansoni and Plasmodium falciparum infections, we applied a log-binomial model to four studies measuring these parameters of a combined 5,849 children in western Kenya. In our studies, malaria contributed 23.3%, schistosomiasis contributed 6.6%, and co-infection contributed 27.6% of the anemia. We conclude that in areas where S. mansoni and P. falciparum are co-endemic, the contribution of schistosomiasis to anemia is masked by anemia resulting from malaria, thus limiting anemia as a useful measure for schistosomiasis control programs in these settings.

Epigenetic mechanisms, like DNA methylation, determine immune cell phenotype. To understand the epigenetic alterations induced by helminth co-infections, we evaluated the longitudinal effect of ascariasis and schistosomiasis infection on CD4+ T cell DNA methylation and the downstream tuberculosis (TB)-specific and BCG-induced immune phenotype. All experiments were performed on human primary immune cells from a longitudinal cohort of recently TB-exposed children. Compared to age-matched uninfected controls, children with active Schistosoma haematobium and Ascaris lumbricoides infection had 751 differentially DNA methylated genes with 72% hyper-methylated. Gene ontology pathway analysis identified inhibition of IFN-γ signaling, cellular proliferation, and the Th1 pathway. Targeted RT-PCR after methyl-specific endonuclease digestion confirmed DNA hyper-methylation of the transcription factors BATF3, ID2, STAT5A, IRF5, PPARg, RUNX2, IRF4 and NFATC1 and cytokines or cytokine receptors IFNGR1, TNFS11, RELT (TNF receptor), IL12RB2 and IL12B (p< 0.001; Sidak-Bonferroni). Functional blockage of the IFN-γ signaling pathway was confirmed with helminth-infected individuals having decreased up-regulation of IFN-γ-inducible genes (Mann-Whitney p < 0.05). Hypo-methylation of the IL-4 pathway and DNA hyper-methylation of the Th1 pathway was confirmed by antigen-specific multidimensional flow cytometry demonstrating decreased TB-specific IFN-γ and TNF and increased IL-4 production by CD4+ T cells (Wilcoxon signed rank P

Schistosomiasis affects over 200 million people worldwide [1] and accounts for an estimated 1.9 million disability-adjusted life years (DALYs) annually [2], with 90% of the burden currently concentrated in Africa. The last decade has witnessed an extraordinary surge of advocacy and funding for neglected tropical diseases (NTDs), including schistosomiasis. Large-scale schistosomiasis control is now implemented in 30 countries in Africa [1], funded primarily through support from the United States Agency for International Development (USAID) and the Department for International Development (DFID), private philanthropic funds from the END Fund and through GiveWell recommendations, and leveraging praziquantel donations from Merck KGaA. However, the number of people still requiring treatment remains daunting [1]. The aim of current public health strategies for schistosomiasis is to decrease morbidity through preventive chemotherapy (PC) (Fig 1) [3]. Periodic large-scale administration of the drug praziquantel focusing on the school-aged population and high-risk adults aims to reduce the prevalence and intensity of infection [4].

Cercarial dermatitis, also known as swimmer's itch, is an allergenic skin reaction followed by intense itching caused by schistosome cercariae penetrating human skin. Cercarial dermatitis outbreaks occur globally and are frequently associated with freshwater lakes and are occasionally associated with marine or estuarine waters where birds reside year-round or where migratory birds reside. In this study, a broadly reactive TaqMan assay targeting 18S rRNA gene (ribosomal DNA [rDNA]) sequences that was based on a genetically diverse panel of schistosome isolates representing 13 genera and 20 species (the 18S rDNA TaqMan assay) was developed. A PCR assay was also developed to amplify a 28S rDNA region for subsequent sequencing to identify schistosomes. When applied to surface water samples seeded with Schistosoma mansoni cercariae, the 18S rDNA TaqMan assay enabled detection at a level of 5 S. mansoni cercariae in 100 liters of lake water. The 18S rDNA TaqMan and 28S rDNA PCR sequencing assays were also applied to 100-liter water samples collected from lakes in Nebraska and Wisconsin where there were reported dermatitis outbreaks. Avian schistosome DNA was detected in 11 of 34 lake water samples using the TaqMan assay. Further 28S rDNA sequence analysis of positive samples confirmed the presence of avian schistosome DNA and provided a preliminary identification of the avian schistosomes in 10 of the 11 samples. These data indicate that the broadly schistosome-reactive TaqMan assay can be effective for rapid screening of large-volume water samples for detection of avian schistosomes, thereby facilitating timely response actions to mitigate or prevent dermatitis outbreaks. Additionally, samples positive by the 18S rDNA TaqMan assay can be further assayed using the 28S rDNA sequencing assay to both confirm the presence of schistosomes and contribute to their identification.

Financial resources tend to be limited in schistosomiasis endemic areas, forcing program managers to balance financial and scientific considerations when selecting detection assays. Therefore, we compared the costs of using single stool Kato-Katz, triplicate stool Kato-Katz, and point-of-contact circulating cathodic antigen (POC-CCA) assays for the detection of Schistosoma mansoni infection. Economic and financial costs were estimated from the viewpoint of a schistosomiasis control program using the ingredients approach. Costs related to specimen collection, sample processing and analysis, and treatment delivery were considered. Analysis inputs and assumptions were tested using one-way and two-way sensitivity analysis. The total per-person cost of performing the single Kato-Katz, triplicate Kato-Katz, and POC-CCA was US$6.89, US$17.54, and US$7.26, respectively. Major cost drivers included labor, transportation, and supplies. In addition, we provide a costing tool to guide program managers in evaluating detection costs in specific settings, as costs may vary temporally and spatially.

The Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) focus is on randomized trials of different approaches to mass drug administration (MDA) in endemic countries in Africa. Because their studies provided an opportunity to evaluate the effects of mass treatment on Schistosoma-associated morbidity, nested cohort studies were developed within SCORE’s intervention trials to monitor changes in a suite of schistosomiasis disease outcomes. This paper describes the process SCORE used to select markers for prospective monitoring and the baseline prevalence of these morbidities in four parallel cohort studies. In July 2009, SCORE hosted a discussion of the potential impact of MDA on morbidities due to Schistosoma infection that might be measured in the context of multi-year control. Candidate markers were reviewed and selected for study implementation. Baseline data were then collected from cohorts of children in four country studies: two in high endemic S. mansoni sites (Kenya and Tanzania), and two in high endemic S. haematobium sites (Niger and Mozambique), these cohorts to be followed prospectively over 5 years. At baseline, 62% of children in the S. mansoni sites had detectable eggs in their stool, and 10% had heavy infections (≥ 400 eggs/g feces). Heavy S. mansoni infections were found to be associated with increased baseline risk of anemia, although children with moderate or heavy intensity infections had lower risk of physical wasting. Prevalence of egg-positive infection in the combined S. haematobium cohorts was 27%, with 5% of individuals having heavy infection (≥50 eggs/10 mL urine). At baseline, light intensity S. haematobium infection was associated with anemia and with lower scores in the social domain of health-related quality-of-life (HRQoL) assessed by Pediatric Quality of Life Inventory. Our consensus on practical markers of Schistosoma-associated morbidity indicated that height, weight, hemoglobin, exercise tolerance, HRQoL, and ultrasound abnormalities could be used as reference points for gauging treatment impact. Data collected over five years of program implementation will provide guidance for future evaluation of morbidity control in areas endemic for schistosomiasis. These cohort studies are registered and performed in conjunction with the International Standard Randomised Controlled Trial Registry trials ISRCTN16755535 , ISRCTN14117624 , ISRCTN95819193 , and ISRCTN32045736 .

Schistosomiasis is a debilitating parasitic disease of humans, endemic in tropical areas, for which no vaccine is available. Evidence points to glycan antigens as being important in immune responses to infection. Here we describe our studies on the comparative humoral immune responses to defined schistosome-type glycan epitopes in Schistosoma mansoni-infected humans, rhesus monkeys and mice. Rhesus anti-glycan responses over the course of infection were screened on a defined glycan microarray comprising semi-synthetic glycopeptides terminating with schistosome-associated or control mammalian-type glycan epitopes, as well as a defined glycan microarray of mammalian-type glycans representing over 400 glycan structures. Infected rhesus monkeys generated a high immunoglobulin G (IgG) antibody response to the core xylose/core α3 fucose epitope of N-glycans, which peaked at 8–11 weeks post infection, coinciding with maximal ability to kill schistosomula in vitro. By contrast, infected humans generated low antibody levels to this epitope. At 18 months following praziquantel therapy to eliminate the parasite, antibody levels were negligible. Mice chronically infected with S. mansoni generated high levels of anti-fucosylated LacdiNAc (GalNAcβ1, 4(Fucα1, 3)GlcNAc) IgM antibodies, but lacked a robust response to the core xylose/core α3 fucose N-glycan antigens compared with other species studied, and their sera demonstrated an intermediate level of schistosomula killing in vitro. These differential responses to parasite glycan antigens may be related to the ability of rhesus monkeys to self-cure in contrast to the chronic infection seen in humans and mice. Our results validate defined glycan microarrays as a useful technology to evaluate diagnostic and vaccine antigens for schistosomiasis and perhaps other infections.

Recently, health measurements have broadened to include the assessment of quality of life (QOL). This study was conducted to assess whether the short form of the World Health Organization (WHO) QOL questionnaire (WHOQOL-BREF) was an effective tool for measuring morbidity due to Schistosoma mansoni infection and whether it could detect an impact of treatment with praziquantel. A total of 724 adults 18–85 years of age were enrolled. At baseline, S. mansoni prevalence was 73.2% by stool examination and 75.4% by circulating cathodic antigen, and there was no association between infection status and WHOQOL-BREF scores. Six months after treatment, S. mansoni prevalence was lower and the proportion of persons with higher WHOQOL-BREF scores significantly increased among persons who were infected at baseline. However, a similar increase was observed in persons not infected at baseline. In areas of high prevalence, the WHOQOL-BREF may not be able to detect the benefits of schistosomiasis control programs.

Objectives Metronidazole and tinidazole are effective treatments for most patients with trichomoniasis but not for individuals who are infected with very resistant strains of Trichomonas vaginalis or persons with hypersensitivity to the 5-nitroimidazole drugs. Thus, there is a need for additional oral therapies to treat trichomoniasis. Methods We screened the US Drug Collection Library against metronidazole-susceptible and resistant strains of T vaginalis. Activity was measured by incubating parasites and drugs for 48 h in the presence of tritiated thymidine. Growth inhibition was determined by the reduction of incorporated radioactivity by compounds at 20 μM in comparison to media control. Drugs that showed good initial activity were further tested to calculate IC 50 values. Drugs with the most promise were tested together with metronidazole to see if there was any combinatorial effect. Results Of the 1040 drugs in the library, 83 (8%) reduced growth of a metronidazole-susceptible T vaginalis strain by at least 20%. Of these, IC 50 values were calculated for 27 compounds and 8 drugs were evaluated in combination with metronidazole. Disulfiram and nithiamide were non-5-nitroimidazole drugs that showed the best activity against parasites when used alone. Albendazole and coenzyme B12 were the most promising compounds to boost the efficacy of metronidazole. Conclusions No one drug was as effective as any of the 5-nitroimidazole compounds. However, disulfiram and nithiamide may be useful to treat individuals with hypersensitivity to 5-nitroimidazole drugs and albendazole and coenzyme B12 may be helpful in combination with metronidazole or tinidazole for treatment of persons with highly resistant T vaginalis infections.

Trichomonas vaginalis is an extracellular protozoan parasite that binds to the epithelium of the human urogenital tract during infection. In this study, we examined the propensities of 26 T. vaginalis strains to bind to and lyse prostate (BPH-1) and ectocervical (Ect1) epithelium and to lyse red blood cells (RBCs). We found that only three of the strains had a statistically significant preference for either BPH-1 (MSA1103) or Ect1 (LA1 and MSA1123). Overall, we observed that levels of adherence are highly variable among strains, with a 12-fold range of adherence on Ect1 cells and a 45-fold range on BPH-1 cells. Cytolysis levels displayed even greater variability, from no detectable cytolysis to 80% or 90% cytolysis of Ect1 and BPH-1, respectively. Levels of adherence and cytolysis correlate for weakly adherent/cytolytic strains, and a threshold of attachment was found to be necessary to trigger cytolysis; however, this threshold can be reached without inducing cytolysis. Furthermore, cytolysis was completely blocked when we prevented attachment of the parasites to host cells while allowing soluble factors complete access. We demonstrate that hemolysis was a rare trait, with only 4 of the 26 strains capable of lysing >20% RBCs with a 1:30 parasite/RBC ratio. Hemolysis also did not correlate with adherence to or cytolysis of either male (BPH-1)- or female (Ect1)-derived epithelial cell lines. Our results reveal that despite a broad range of pathogenic properties among different T. vaginalis strains, all strains show strict contact-dependent cytolysis.

Since the advent of techniques for the expression of recombinant peptide antigens, the availability of human vaccines for parasitic diseases has been ‘imminent’. Yet vaccines based on recombinant proteins are still largely aspirations, not realities. It is now apparent that vaccine development needs additional knowledge about host protective immune response(s), antigen characteristics, and the delivery required to induce those responses. The most successful immune protection against parasites has been generated by infection and treatment, the induction of protective immunity by truncating the course of an infection with drug treatment. Here, we consider the characteristics of an effective, protective anti-parasite vaccine and propose a conceptual framework to aid parasite vaccine development using malaria and schistosomiasis as examples.

A better understanding of the mechanism of anemia associated with Schistosoma mansoni infection might provide useful information on how treatment programs are implemented to minimize schistosomiasis-associated morbidity and maximize treatment impact. We used a cross-sectional study with serum samples from 206 Kenyan school children to determine the mechanisms in S. mansoni-associated anemia. Serum ferritin and soluble transferrin receptor levels were measured by using an enzyme-linked immunosorbent assay. Results suggest that S. mansoni-infected persons are more likely (odds ratio = 3.68, 95% confidence interval = 1.33–10.1) to have levels of serum ferritin (> 100 ng/mL) that are associated with anemia of inflammation (AI) than S. mansoni-uninfected children. Our results suggest that AI is the most common form of anemia in S. mansoni infections. In contrast, the mechanism of anemia in S. mansoni-uninfected children was iron deficiency. Moreover, the prevalence of AI in the study participants demonstrated a significant trend with S. mansoni infection intensity (P < 0.001). Our results are consistent with those observed in S. japonicum-associated anemia.

Schistosomiasis control programs aim to reduce morbidity but are evaluated by infection prevalence and intensity reduction. We present baseline cross-sectional data from a nested cohort study comparing indicators of mor- bidity for measuring program impact. Eight hundred twenty-two schoolchildren 7-8 years of age from Nyanza Province, Kenya, contributed stool for diagnosis of Schistosoma mansoni and soil-transmitted helminths (STH) and blood smears for malaria, and were evaluated for anemia, quality of life, exercise tolerance, anthropometry, and ultrasound abnormal- ities. Schistosoma mansoni, STH, and malaria infection prevalence were 69%, 25%, and 8%, respectively. Only anemia and S. mansoni infection (adjusted odds ratio (aOR) = 1.70; confidence interval (CI) = 1.03-2.80), and hepatomegaly and heavy S. mansoni infection (aOR = 2.21; CI = 1.19-4.11) were associated. Though anemia and hepatomegaly appeared most useful at baseline, additional morbidity indicators may be sensitive longitudinal measures to evaluate schistosomi- asis program health impact.

The Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) was established in 2008 to answer strategic questions about schistosomiasis control. For programme managers, a high-priority question is: what are the most cost-effective strategies for delivering preventive chemotherapy (PCT) with praziquantel (PZQ)? This paper describes the process SCORE used to transform this question into a harmonized research protocol, the study design for answering this question, the village eligibility assessments and data resulting from the first year of the study. Beginning in 2009, SCORE held a series of meetings to specify empirical questions and design studies related to different schedules of PCT for schistosomiasis control in communities with high (gaining control studies) and moderate (sustaining control studies) prevalence of Schistosoma infection among school-aged children. Seven studies are currently being implemented in five African countries. During the first year, villages were screened for eligibility, and data were collected on prevalence and intensity of infection prior to randomisation and the implementation of different schemes of PZQ intervention strategies. These studies of different treatment schedules with PZQ will provide the most comprehensive data thus far on the optimal frequency and continuity of PCT for schistosomiasis infection and morbidity control. We expect that the study outcomes will provide data for decision-making for country programme managers and a rich resource of information to the schistosomiasis research community. The trials are registered at International Standard Randomised Controlled Trial registry (identifiers: ISRCTN99401114 , ISRCTN14849830 , ISRCTN16755535 , ISRCTN14117624 , ISRCTN95819193 and ISRCTN32045736 ).

Infection of mammals by the parasitic helminth Schistosoma mansoni induces antibodies to glycan antigens in worms and eggs, but the differential nature of the immune response among infected mammals is poorly understood. To better define these responses, we used a shotgun glycomics approach in which N-glycans from schistosome egg glycoproteins were prepared, derivatized, separated, and used to generate an egg shotgun glycan microarray. This array was interrogated with sera from infected mice, rhesus monkeys, and humans and with glycan-binding proteins and antibodies to gather information about the structures of antigenic glycans, which also were analyzed by mass spectrometry. A major glycan antigen targeted by IgG from different infected species is the FLDNF epitope [Fucα3GalNAcβ4(Fucα3)GlcNAc-R], which is also recognized by the IgG monoclonal antibody F2D2. The FLDNF antigen is expressed by all life stages of the parasite in mammalian hosts, and F2D2 can kill schistosomula in vitro in a complement-dependent manner. Different antisera also recognized other glycan determinants, including core β-xylose and highly fucosylated glycans. Thus, the natural shotgun glycan microarray of schistosome eggs is useful in identifying antigenic glycans and in developing new anti-glycan reagents that may have diagnostic applications and contribute to developing new vaccines against schistosomiasis.

Such isolates should undergo drug susceptibility testing periodically to detect emerging resistance., Nitroimidazoles (metronidazole and tinidazole) are the only recommended drugs for treating Trichomonas vaginalis infection, and previous samples that assessed resistance of such isolates have been limited in geographic scope. We assessed the prevalence of in vitro aerobic metronidazole and tinidazole resistance among T. vaginalis isolates from multiple geographic sites in the United States. Swab specimens were obtained from women who underwent routine pelvic examinations at sexually transmitted disease clinics in 6 US cities. Cultured T. vaginalis isolates were tested for nitroimidazole resistance (aerobic minimum lethal concentration [MLC] >50 µg/mL). Of 538 T. vaginalis isolates, 23 (4.3%) exhibited low-level in vitro metronidazole resistance (minimum lethal concentrations 50–100 µg/mL). No isolates exhibited moderate- to high-level metronidazole resistance or tinidazole resistance. Results highlight the possibility that reliance on a single class of antimicrobial drugs for treating T. vaginalis infections may heighten vulnerability to emergence of resistance. Thus, novel treatment options are needed.

Background Sexually transmitted infections (STIs) are associated with an increased risk of HIV infection. To model the interaction between STIs and HIV infection, we evaluated the capacity of the pigtail macaque model to sustain triple infection with Trichomonas vaginalis, Chlamydia trachomatis, and SHIVSF162P3.

A Chinese rhesus macaque infected with the pathogenic CCR5-tropic clade C simian-human immunodeficiency virus, SHIV-1157ipd3N4, had persistent viremia, depletion of CD4(+) T cells to

Background. Age prevalence curves for areas in which schistosomiasis is endemic suggest that humans develop partial immunity to reinfection beginning in early adolescence. We conducted a 2-year longitudinal study to determine whether children infected with Schistosoma mansoni develop protection-related immune responses after treatment with praziquantel and whether the development of these immune responses is accelerated by frequent treatment after reinfection. Methods. Children (8‐10 years old) were tested for S. mansoni every 4 months and treated with praziquantel when positive (arm A; ) or were tested and treated at the end of the 2-year follow-up period (arm B; n p 68 ). n p 49 Results. Children in arm A who remained free of infection during follow-up had significantly higher baseline levels of schistosome-specific immunoglobulin E (IgE) than did children with 2 repeat diagnoses of S. mansoni infection. Children with 2 repeat diagnoses of S. mansoni infection had significantly increased levels of antischistosome IgE and CD23 + B cells after receiving 3 praziquantel treatments over the course of follow-up. No increase in either parameter was seen in children who received only the baseline praziquantel treatment. Conclusions. B cell activation and anti-schistosome IgE are associated with resistance to S. mansoni in children, and these immunological parameters can be increased by multiple rounds of infections and praziquantel-induced cures. Schistosoma mansoni age prevalence curves for areas of endemicity suggest that intensity and prevalence of infection peak during the early teenage years. Prevalence then plateaus while infection intensity sharply declines as individuals enter the third decade of life. Immunologic studies suggest that the decline in intensity is in part attributable to the development of immunity to new infections [1‐3]. Given that the life span of S. mansoni worms is ∼5‐10 years [4, 5], this resistance to

Trichomonas vaginalis is a protozoan parasite that is the cause of the most common non-viral sexually transmitted disease, trichomoniasis. Metronidazole and tinidazole are the only drugs approved for treatment of T. vaginalis infections in the USA. However, drug resistance exists and some patients are allergic to these medications. Furthermore, the exact mechanism of metronidazole resistance remains undefined and current testing methods require several weeks before results are available. Identification of the mechanism of drug resistance may lead to the development of molecular tools to detect drug resistance, and quicker results for clinical treatment. In a recent study, Chinese T. vaginalis isolates that were polymerase chain reaction (PCR) positive for Mycoplasma hominis DNA demonstrated greater in vitro resistance to metronidazole than isolates with no evidence of M. hominis infection. To evaluate this finding in isolates from a distinct epidemiologic setting, we tested 55 T. vaginalis isolates collected from patients in the USA through the Centers for Disease Control and Prevention metronidazole susceptibility testing service. One half of the isolates demonstrated resistance to metronidazole by an in vitro sensitivity assay. Of the metronidazole-resistant T. vaginalis isolates, 18% were PCR positive for M. hominis, as were 22% of the metronidazole-susceptible T. vaginalis isolates (p = 0.746). We also observed no change in metronidazole sensitivity of two infected T. vaginalis isolates after they were cleared of their M. hominis infection by culturing the isolates in antibiotics. Thus, M. hominis infection of USA T. vaginalis isolates did not correlate with in vitro resistance to metronidazole.

Worldwide, approximately 90% of all human immunodeficiency virus (HIV) transmissions occur mucosally; almost all involve R5 strains. Risks of sexual HIV acquisition are highest for rectal, then vaginal, and finally oral exposures.Mucosal lacerations may affect the rank order of susceptibility to HIV but cannot be assessed in humans. We measured relative virus transmissibility across intact mucosae in macaques using a single stock of SHIV-1157ipd3N4, a simian-human immunodeficiency virus encoding a primary R5 HIV clade C env (SHIV-C).The penetrability of rhesus macaque mucosae differed significantly, with rectal challenge requiring the least virus, followed by vaginal and then oral routes (P = .031, oral vs vaginal; P.001 rectal vs vaginal). These findings imply that intrinsic mucosal properties are responsible for the differential mucosal permeability. The latter paralleled the rank order reported for humans, with relative risk estimates within the range of epidemiological human studies. To test whether inflammation facilitates virus transmission--as predicted from human studies--we established a macaque model of localized buccal inflammation. Systemic infection occurred across inflamed but not normal buccal mucosa.Our primate data recapitulate virus transmission risks observed in humans, thus establishing R5 SHIV-1157ipd3N4 in macaques as a robust model system to study cofactors involved in human mucosal HIV transmission and its prevention.

OBJECTIVE To investigate trends in the efficacy of praziquantel (PZQ) suggestive of the emergence of drug resistance against Schistosoma mansoni infection after 12.5 years of intense, repeated use in a small geographic area along the shores of Lake Victoria. METHODS As part of a longitudinal study, 178 men occupationally exposed to schistosomes were repeatedly tested for S. mansoni infection at 4- to 6-week intervals and treated with PZQ at each reinfection. We compared cure rates by year of study and examined factors associated with cure failure in a multivariate logistic regression model. RESULTS Overall, the cure rate after a single dose of PZQ was 66%, ranging annually from 36% to 82%. In multivariate analysis, failure to cure after 1 PZQ dose was significantly associated with high intensity of infection and having fewer previous exposures to dying worms. Even after adjustment for these factors, treatments administered in 2006 were significantly more likely to result in cure failures than treatments administered in 2004, the year in which PZQ efficacy was highest. While cure rates varied over the course of 12 years, there was no consistent downward trend towards decreased efficacy over time. In years for which malacological data were available, periods of low PZQ efficacy coincide with high rates of S. mansoni infection in nearby snail populations. CONCLUSION We did not find a pattern of cure failures consistent with development of clinical resistance to PZQ in our intensely treated cohort.

Flow cytometric analyses were performed to evaluate HLA-DR (+) activated T lymphocytes (Tact; CD3 (+)/CD4 (+)/CD25(medium)) and T regulatory cells (Treg; CD3 (+)/CD4(+)/CD25(high)) in the circulation of children 8-10 years of age living in an area endemic for both Plasmodium falciparum and Schistosoma mansoni in western Kenya. Those children with only S. mansoni had a higher mean percentage of HLA-DR (+) Tact than those who were co-infected with these two intravascular parasites. The proportion of circulating Treg was comparable in children with only schistosomiasis and both schistosomiasis and malaria. However, the mean level of memory Treg (Treg expressing CD45RO (+)) in those with dual infections was lower than in children with schistosomiasis alone. These imbalances in Tact and Treg memory subsets in children infected with both schistosomiasis and malaria may be related to the differential morbidity or course of infection attributed to coinfections with these parasites.

Restriction fragment length polymorphism (RFLP) analysis using a multilocus heat-inducible cytoplasmic heat-shock protein 70 (Hsp70) hybridization probe with EcoRI-digested genomic DNA was used in molecular typing of 129 Trichomonas vaginalis isolates. Results indicate that Trichomonas organisms exhibit considerable polymorphism in their Hsp70 RFLP patterns. Analysis of seven American Type Culture Collection reference strains and 122 clinical isolates, including 84 isolates from Jackson, Mississippi, 18 isolates from Atlanta, Georgia, and 20 isolates from throughout the United States, showed 105 distinct Hsp70 RFLP pattern subtypes for Trichomonas. Phylogenetic analysis of the Hsp70 RFLP data showed that the T. vaginalis isolates were organized into two clonal lineages. These results illustrate the substantial genomic diversity present in T. vaginalis and indicate that a large number of genetically distinct Trichomonas isolates may be responsible for human trichomoniasis in the United States.

Infection with Schistosoma mansoni remains a major public health problem in many resource-limited countries in the world. There are costs and logistical challenges associated with chemotherapy and sanitation-based control, and a vaccine might be needed as an additional tool for long-term control or elimination [1]. However, vaccine development has been hindered by limited translational data from studies in laboratory animals and an inadequate understanding of the protective immune mechanisms in humans [2]. Recent data showing that a proportion of adults occupationally exposed to S. mansoni can become more resistant to reinfection [3] have encouraged continued research into a vaccine. Studies in the human host to further characterize the immune responses that correlate with protection should help in vaccine development. In many field-based studies, high levels of parasite-specific IgE correlate with resistance in schistosomiasis [4 - 6], yet our understanding of the mechanisms of IgE regulation is limited. Remarkably, although B cells are the producers of IgE, little is known about human B cell function in schistosomiasis. In mice, B cells have been shown to play an important role in antiparasite immunity, not only as antibody producers but also in promoting an optimal and sustained T cell response [7]. It remains important to define the roles that human B cells play in immunity to schistosomiasis. IgE most likely exerts in vivo effector and regulatory function(s) through its high-affinity (FceRI) and/or low-affinity (FceRII or CD23) receptors on myeloid cells [8]. CD23 is also expressed by B cells. In some settings, CD23-bound IgE cross-linked by antigen activates B cells, and it has been shown to regulate IgE production. However, although CD23 may exercise opposing roles in IgE immune responses in mice [8, 9], it appears to be a positive regulator in humans and may have an important role in human immunology [10]. IgE-antigen complexes also enhance human B cell antigen presentation to T cells in vitro, although the specific intracellular mechanisms have not been detailed [9, 11, 12]. Thus, the production and regulation of IgE may be mediated in part through CD23+ B cells [8, 12-17]. The mechanisms of high IgE output at the level of the B cell are not well characterized in schistosomiasis, and it is not understood why some individuals develop high IgE levels and others do not, despite generally comparable levels of exposure. We have studied CD23 expression on B cells in a unique setting involving the development of demonstrable resistance to natural reinfection by S. mansoni in humans. We show that levels of both CD19+CD23+ B cells and circulating soluble CD23 (sCD23) correlate with the development of resistance to reinfection and with other indicators of resistance, such as eosinophilia, during a defined period of multiple praziquantel treatments and reinfections.

Background. Schistosomiasis and strongyloidiasis cause substantial morbidity and mortality among hundreds of millions of infected persons worldwide. In the United States, these infections are most commonly found among international travelers, immigrants, and refugees from areas of endemicity. Refugees resettled to the United States since 2000 include >3800 "Lost Boys and Girls" of Sudan and 8000 Somali Bantu. Many Lost Boys and Girls of Sudan reported chronic abdominal pain only since arrival, and some received diagnoses of schistosomiasis or strongyloidiasis. We assessed seroprevalence of these infections among these refugees and hypothesized an association between infection and abdominal pain. Methods. We offered a survey assessing chronic abdominal pain and serologic testing for schistosomiasis and strongyloidiasis to all 800 attendees of a Lost Boys and Girls of Sudan reunion in the United States. Serologic testing was performed on preimmigration specimens obtained from 100 United States-bound Somali Bantu refugees. Results. Of the 462 Sudanese refugees (58%) tested, 44% and 46% were seropositive for schistosomiasis (primarily due to Schistosoma mansoni) and strongyloidiasis, respectively; 24% of those who tested positive for schistosomiasis had S. mansoni antigenemia. Forty-six percent reported chronic abdominal pain, which was not associated with either infection. Among 100 Somali Bantu, 73% and 23% tested seropositive for schistosomiasis (primarily due to Schistosoma haematobium) and strongyloidiasis, respectively. Conclusions. The high seroprevalence of schistosomiasis and strongyloidiasis among Sudanese Lost Boys and Girls and Somali Bantu refugees supports presumptive treatment for these refugees. Current refugee resettlement policies inadequately address these diseases; our data support consideration of predeparture presumptive therapy for all refugees from areas of endemicity.

Background The current reference test for the detection of S. mansoni in endemic areas is stool microscopy based on one or more Kato-Katz stool smears. However, stool microscopy has several shortcomings that greatly affect the efficacy of current schistosomiasis control programs. A highly specific multiplex real-time polymerase chain reaction (PCR) targeting the Schistosoma internal transcriber-spacer-2 sequence (ITS2) was developed by our group a few years ago, but so far this PCR has been applied mostly on urine samples. Here, we performed more in-depth evaluation of the ITS2 PCR as an alternative method to standard microscopy for the detection and quantification of Schistosoma spp. in stool samples. Methodology/Principal findings Microscopy and PCR were performed in a Senegalese community (n = 197) in an area with high S. mansoni transmission and co-occurrence of S. haematobium, and in Kenyan schoolchildren (n = 760) from an area with comparatively low S. mansoni transmission. Despite the differences in Schistosoma endemicity the PCR performed very similarly in both areas; 13–15% more infections were detected by PCR when comparing to microscopy of a single stool sample. Even when 2–3 stool samples were used for microscopy, PCR on one stool sample detected more infections, especially in people with light-intensity infections and in children from low-risk schools. The low prevalence of soil-transmitted helminthiasis in both populations was confirmed by an additional multiplex PCR. Conclusions/Significance The ITS2-based PCR was more sensitive than standard microscopy in detecting Schistosoma spp. This would be particularly useful for S. mansoni detection in low transmission areas, and post-control settings, and as such improve schistosomiasis control programs, epidemiological research, and quality control of microscopy. Moreover, it can be complemented with other (multiplex real-time) PCRs to detect a wider range of helminths and thus enhance effectiveness of current integrated control and elimination strategies for neglected tropical diseases., Author Summary In the developing world, over 207 million people are infected with parasitic Schistosoma worms. Schistosoma mansoni is one of the most widespread species, and its routine diagnosis is based on microscopic detection of parasite eggs in stool samples. This technique is, however, highly observer-dependent and has suboptimal sensitivity. We compared the performance of stool microscopy with the highly specific real-time polymerase chain reaction (PCR) we recently described for the detection and quantification of parasite–specific DNA. We tested stool samples collected at two different epidemiological settings: a Senegalese population (n = 197) from a high transmission area where S. mansoni and S. haematobium are co-endemic and a Kenyan school population (n = 760) selected from zones with comparatively low S. mansoni transmission. Microscopy mostly missed low intensity infections that PCR was able to detect. Consequently, the PCR may be very useful for the detection of S. mansoni in areas with low levels of infection. Furthermore, being a highly standardized diagnostic procedure, the PCR may improve schistosomiasis control programs, epidemiological research, and quality control of microscopy. Also it can be easily combined with other PCRs to detect a wider range of helminth infections in a single stool sample.

The chapter talks about the mechanisms of resistance to antiparasitic agents. Plasmodium falciparum, the most virulent species, which adapts more easily to environmental constraints in tropical areas, has become the dominant species, and its resistance to chloroquine, to sulfadoxine-pyrimethamine, and, further, to all known drugs has developed to various degrees. True resistance is more likely in anthroponotic forms of leishmaniasis, such as those caused by Leishmania donovani and Leishmania tropica, because the zoonotic species that infect primarily animals, with humans as an occasional host, rarely encounter drugs. Laboratory or field isolates with resistance to pentavalent antimonials are also killed effectively by paromomycin and miltefosine. Several factors contribute to the emergence of drug- resistant parasites. Public health interventions to correct these factors have not always been successful and would benefit from a better understanding of the drug resistance mechanisms used by parasites. These mechanisms are very diverse and have been difficult to study, but recent technological advances now provide long-awaited tools that will facilitate the task. The genome sequences for P. falciparum, T. vaginalis, L. major, T. brucei, and S. mansoni have been compiled. When these data are used, for example, in combination with microarray technology, where the DNA of drug-resistant parasite strains is compared to that of drugsusceptible strains, identification of the genes that confer resistance should proceed even more rapidly than in the last few years.

Drug susceptibility tests fall into four broad categories: in vivo tests, in vitro tests, tests with experimental animals, and molecular tests. These different categories of tests provide complementary information. At one end of the spectrum, molecular tests analyze parasites at their most basic biologic level, without any outside interference. Most drug resistance tests in malaria concern Plasmodium falciparum, the most prevalent and virulent species and the most prone to the development of resistance. Incorporating pharmacokinetic parameters is now considered essential for true resistance identification within partners of artemisinins, which are frequently poorly absorbed or slowly eliminated drugs. While treatment failures for Trichomonas vaginalis infections have often been disregarded as being due to poor patient compliance or rapid reinfection, there is an increasing recognition that true clinical resistance exists and may be increasing, thus necessitating accurate drug susceptibility testing of patient isolates. Treatment failure in leishmaniasis may result from either true drug resistance or patient immunodeficiencies that preclude effective chemotherapeutic action. Differentiation of these two possibilities is important for both individual patient care and general public health. A standardized in vivo method for detection of drug resistance that was designed for testing trypanosomes that infect cattle can also be applied to those that infect humans. Investigation of drug resistance mechanisms of schistosomes is more difficult and time-consuming than those associated with protozoan infections.

A high level of serum IgE is generally associated with human resistance to schistosomes, though the protective mechanisms of IgE remain undefined. We recently reported that whereas some individuals who are occupationally hyperexposed to Schistosoma mansoni display resistance to reinfection, others remain highly susceptible, in some cases due to HIV-1 co-infection. As IgE functions, in part, through FcepsilonRI on mast cells, we characterized circulating CD117(+) FcepsilonRI(+) mast cell precursors in this population. Surprisingly, a higher percentage of CD117(+) cells correlated with a susceptible phenotype in HIV-1 seronegative participants with schistosomiasis. There was no association between percentages of peripheral CD117(+) cells and susceptibility to reinfection in persons with HIV-1. Serum levels of polyclonal IgE were inversely correlated with percentages of CD117(+) cells regardless of HIV-1 status. Thus, immature mast cells may affect IgE availability, or IgE may affect immature mast cells, altering the balance of host susceptibility and resistance to schistosomes.

Background: The clinical spectrum of visceral leishmaniasis (VL), a chronic intracellular parasitic disease, ranges from a subclinical, asymptomatic infection to severe clinical disease (kala-azar). In experimental leishmaniasis, mice that have a Th1 response to infection tend to have limited disease while a Th2 response is associated with disease progression. Humans with VL most often have mixed rather than polarized responses. However, most clinical studies have used methods that require a relatively large sample volume, thus limiting their scope. Measuring multiple cytokine levels in blood samples using a multiplexed microsphere assay (MMA) may be useful to further evaluate the Th1/Th2 paradigm in humans. Methods: Bangladeshi individuals (n = 120) living in an area endemic for VL were categorized into one of the five clinical categories. Sera from these individuals were measured for levels of IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12, IFN-γ, and TNF-α by multiplexed microsphere cytokine immunoassay. Results: Circulating IL-8, IL-10, and IL-12 differed significantly among the clinical groups. Persons with kala-azar demonstrated the highest median levels of IL-8 and IL-10 but lower median levels of IL-12. Conclusions: The MMA for cytokines is an extremely time-and sample-efficient method for characterizing circulating cytokine levels in visceral leishmaniasis patients. © 2006 International Society for Analytical Cytology

Objective: To evaluate the hypothesis that parasitic infections that induce T-helper type 2 (Th2) immune responses, such as schistosomiasis, upregulate HIV-1 replication. Design: The effect of concomitant Schistosoma mansoni infection was tested in a primate model of acute and chronic simian-human immunodeficiency virus (SHIV) infection in rhesus macaques using a novel SHIV strain encoding the R5 env gene of a primary HIV clade C isolate from sub-Saharan Africa. Methods: S. mansoni-infected rhesus macaques and controls were exposed to SHIV to assess the effects of schistosomiasis on acute viral infection. Effects on chronic viral infection were evaluated by exposing virus-infected animals to parasites. S. mansoni infection was confirmed by the presence of parasite eggs in stool and eosinophilia. Viral RNA loads, cytokine and chemokine mRNA expression were measured by real time reverse transcription–PCR. Results: S. mansoni coinfection increased the expression of Th2-associated cytokine responses and SHIV replication during both acute and chronic phases of SHIV infection. Conclusions: These results support the hypothesis that concomitant schistosomiasis upregulates replication of immunodeficiency viruses in coinfected hosts, raising the possibility that parasite-infected individuals may also be more susceptible to acquisition of HIV-1 infection.

To investigate whether infection with human immunodeficiency virus 1 (HIV-1) affects fibrosis development in patients infected with Schistosoma mansoni, we evaluated schistosomiasis-induced pathology in the livers of Kenyan patients co-infected with HIV-1. Compared with persons with schistosomiasis alone (n = 58), there were no significant differences in distribution of ultrasound-detectable pathology in persons with HIV-1 co-infection (n = 23). Similarly, serum aspartate aminotransferase levels were not significantly different in HIV-1+ individuals. Hepatic fibrosis was associated with significantly decreased CD4+ T cell counts, even in the absence of HIV-1 infection. These data suggest that HIV-1 co-infection does not significantly alter the proportion of patients experiencing schistosomiasis-induced fibrosis, but pathology associated with S. mansoni infections leads to CD4+ T cell reductions and thereby may exacerbate the effects of HIV-1 in co-infected individuals.

We evaluated 44 novel cationic compounds for activity against metronidazole-sensitive and -resistant Trichomonas vaginalis isolates. Six compounds in three different structural classes demonstrated 50% inhibitory concentrations as low as 1 μM against both sensitive and resistant isolates, suggesting a mode of action independent of parasite biochemical pathways that confer resistance to 5-nitroimidazoles.

Helminth infections elicit an immune response potentially enhancing susceptibility to mycobacterial diseases. Schistosomiasis and infection with Mycobacterium ulcerans show a remarkable similarity in epidemiologic characteristics in Ghana. In 2000, a case-control study was conducted in three districts in Ghana endemic for M. ulcerans. One hundred six patients with confirmed M. ulcerans disease and 106 matched community controls were included. Schistosome infection of these patients and controls was measured by an enzyme-linked immunosorbent assay that detected circulating anodic antigen in serum. Fifty percent of the participants tested positive for schistosomiasis. There was no difference in detection rates among patients and matched controls. Similarly, there were no differences in worm burden between patients and controls. These results do not support the hypothesis that susceptibility to M. ulcerans disease is driven by a co-infection with schistosomes.

Distribution of chemokine receptors CCR5 and CXCR4, which are also coreceptors for human immunodeficiency virus type 1 invasion of cells, was measured on the surfaces of CD4 + T cells and monocytes in peripheral blood samples from a group of Kenyan car washers. Patients with active schistosomiasis displayed higher cell surface densities of these receptors than did cured schistosomiasis patients.