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Campylobacter jejuni and Campylobacter coli are the leading cause of human gastroenteritis in the industrialized world and an emerging threat in developing countries. The incidence of campylobacteriosis in South America is greatly underestimated, mostly due to the lack of adequate diagnostic methods. Accordingly, there is limited genomic and epidemiological data from this region. In the present study, we performed a genome-wide analysis of the genetic diversity, virulence, and antimicrobial resistance of the largest collection of clinical C. jejuni and C. coli strains from Chile available to date (n = 81), collected in 2017–2019 in Santiago, Chile. This culture collection accounts for more than one third of the available genome sequences from South American clinical strains. cgMLST analysis identified high genetic diversity as well as 13 novel STs and alleles in both C. jejuni and C. coli. Pangenome and virulome analyses showed a differential distribution of virulence factors, including both plasmid and chromosomally encoded T6SSs and T4SSs. Resistome analysis predicted widespread resistance to fluoroquinolones, but low rates of erythromycin resistance. This study provides valuable genomic and epidemiological data and highlights the need for further genomic epidemiology studies in Chile and other South American countries to better understand molecular epidemiology and antimicrobial resistance of this emerging intestinal pathogen. Author summary: Campylobacter is the leading cause of bacterial gastroenteritis worldwide and an emerging and neglected pathogen in South America. In this study, we performed an in-depth analysis of the genome sequences of 69 C. jejuni and 12 C. coli clinical strains isolated from Chile, which account for over a third of the sequences from clinical strains available from South America. We identified a high genetic diversity among C. jejuni strains and the unexpected identification of clade 3 C. coli strains, which are infrequently isolated from humans in other regions of the world. Most strains harbored the virulence factors described for Campylobacter. While ~40% of strains harbored mutation in the gyrA gene described to confer fluoroquinolone resistance, very few strains encoded the determinants linked to macrolide resistance, currently used for the treatment of campylobacteriosis. Our study contributes to our knowledge of this important foodborne pathogen providing valuable data from South America. [ABSTRACT FROM AUTHOR]

We describe a case of chronic meningoencephalitis with hydrocephalus caused by Cryptococcus bacillisporus (VGIII) in an immunocompetent patient from Santa Cruz, Bolivia. This first report of a member of the Cryptococcus gattii species complex from Bolivia suggests that C. bacillisporus (VGIII) is present in this tropical region of the country and complements our epidemiological and clinical knowledge of this group of emerging fungal pathogens in South America. [ABSTRACT FROM AUTHOR]

• Due to the rapidly emerging SARS-CoV-2 pandemic and its tremendous public health challenges worldwide, there is a critical demand for rapid and easy to perform diagnostic assays. • The rapid antigen detection test evaluated here had a high diagnostic sensitivity and specificity in respiratory samples obtained from patients who mainly presented during the first week of COVID-19. • Rapid antigen detection has the potential to become an important tool for the early diagnosis of SARS-CoV-2, particularly in situations with limited access to molecular methods. In the context of the coronavirus disease 2019 (COVID-19) pandemic, the development and validation of rapid and easy-to-perform diagnostic methods are of high priority. This study was performed to evaluate a novel rapid antigen detection test (RDT) for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in respiratory samples. The fluorescence immunochromatographic SARS-CoV-2 antigen test (Bioeasy Biotechnology Co., Shenzhen, China) was evaluated using universal transport medium with nasopharyngeal (NP) and oropharyngeal (OP) swabs from suspected COVID-19 cases. Diagnostic accuracy was determined in comparison to SARS-CoV-2 real-time (RT)-PCR. A total of 127 samples were included; 82 were RT-PCR-positive. The median patient age was 38 years, 53.5% were male, and 93.7% were from the first week after symptom onset. Overall sensitivity and specificity were 93.9% (95% confidence interval 86.5–97.4%) and 100% (95% confidence interval 92.1–100%), respectively, with a diagnostic accuracy of 96.1% and Kappa coefficient of 0.9. Sensitivity was significantly higher in samples with high viral loads. The RDT evaluated in this study showed a high sensitivity and specificity in samples mainly obtained during the first week of symptoms and with high viral loads, despite the use of a non-validated sample material. The assay has the potential to become an important tool for early diagnosis of SARS-CoV-2, particularly in situations with limited access to molecular methods. [ABSTRACT FROM AUTHOR]

Scrub typhus is a potentially fatal rickettsiosis caused by Orientia species intracellular bacteria of the genus Orientia. Although considered to be restricted to the Asia Pacific region, scrub typhus has recently been discovered in southern Chile. We analyzed Orientia gene sequences of 16S rRNA (rrs) and 47-kDa (htrA) from 18 scrub typhus patients from Chile. Sequences were ≥99.7% identical among the samples for both amplified genes. Their diversity was 3.1%-3.5% for rrs and 11.2%-11.8% for htrA compared with O. tsusugamushi and 3.0% for rrs and 14.8% for htrA compared with Candidatus Orientia chuto. Phylogenetic analyses of both genes grouped the specimens from Chile in a different clade from other Orientia species. Our results indicate that Orientia isolates from Chile constitute a novel species, which, until they are cultivated and fully characterized, we propose to designate as Candidatus Orientia chiloensis, after the Chiloé Archipelago where the pathogen was identified. [ABSTRACT FROM AUTHOR]

Background: Scrub typhus is an emerging vector-borne zoonosis, caused by Orientia spp. and transmitted by larvae of trombiculid mites, called chiggers. It mainly occurs within a region of the Asia-Pacific called the tsutsugamushi triangle, where rodents are known as the most relevant hosts for the trombiculid vector. However, the reservoir(s) and vector(s) of the scrub typhus outside Asia-Pacific are unknown. The disease has recently been discovered on and is considered endemic for Chiloé Island in southern Chile. The aim of the present work was to detect and determine the prevalence of chiggers on different rodent species captured in probable sites for the transmission of orientiae responsible for scrub typhus on Chiloé Island in southern Chile and to molecularly examine collected chiggers for the presence of Orientia DNA. Methodology/Principal findings: During the austral summer 2018, rodents were live-trapped in six sites and examined for chigger infestation. All study sites were rural areas on Chiloé Island, previously identified as probable localities where human cases acquired the scrub typhus. During a total of 4,713 trap-nights, 244 rodents of seven species were captured: the most abundant was Abrothrix olivacea. Chiggers were detected on all seven rodent species with a 55% prevalence rate. Chiggers showed low host specificity and varied according to site specific host abundance. Three genera of trombiculids were identified. Herpetacarus was the most abundant genus (93%), prevalent in five of the six sites. Infestation rates showed site specific differences, which were statistically significant using a GLM model with binomial errors. Molecular analyses proved that 21 of 133 (15.8%) mite pools were positive for Orientia species, all of them belonged to the genus Herpetacarus. Conclusions/Significance: This study firstly reports the presence of different rodent-associated chigger mites positive for Orientia sp., in a region endemic for scrub typhus in southern Chile. Herpetacarus and two other genera of mites were found with high infestation rates of rodents in sites previously identified as probable exposure of scrub typhus cases. A substantial percentage of mite pools were positive for Orientia DNA, suggesting that chigger mites serve as vectors and reservoirs of this emerging zoonosis in South America. Author summary: Scrub typhus is a chigger-transmitted zoonotic infection caused by Orientia species, which is endemic to the tsutsugamushi triangle in Asia-Pacific region. Recently, a focus of scrub typhus in South America has been confirmed on Chiloé Island in southern Chile. However, the vectors of scrub typhus in this region remain unknown. We undertook a survey to study the presence of chiggers on different rodent species in areas identified as probable sites of exposure to scrub typhus on Chiloé Island. The study showed that 55% of rodents were infested by trombiculids. Three mite genera were identified, of which Herpetacarus was the most abundant. Chiggers showed low host specificity, but spatial differences. Using molecular techniques, the trombiculid mites were found to be infected with Orientia species. These findings suggest that chigger mites play a role in the life cycle and transmission of this emerging infectious disease in Chile. [ABSTRACT FROM AUTHOR]

The so far known species of the Anopheles Claviger Complex, Anopheles claviger s.s. and Anopheles petragnani, can only be distinguished by partial overlapping characteristics of immature stages and by nucleotide sequence variation of the genomic ribosomal DNA (rDNA) internal transcribed spacer 2 (ITS2) region. The known distribution of An. petragnani is so far restricted to the western Mediterranean region, whereas An. claviger s.s. occurs across most of Europe, up to the Middle East and North Africa. In our study, we investigated the larval mosquito fauna in rock pools of the Murg valley (Black Forest, Germany) once a month from April to December 2015. Among other species, larvae belonging to the Anopheles Claviger Complex were found. The fourth instar larvae were morphologically identified by chaetotaxy of the head and abdomen. The results were confirmed by a multiplex PCR and additional sequencing of the amplificates. Of the 1289 collected larvae from the rock pools, seven belonged to the Anopheles Claviger Complex. Five individuals were determined morphologically as An. petragnani and two as An. claviger s.s. The associated mosquito fauna comprised of Aedes japonicus japonicus (548 individuals), Culex pipiens s.l. and Culex torrentium (493 individuals) and Culex hortensis (241 individuals). This is the first record of An. petragnani north of the Alps. Further studies will reveal whether this is an isolated population of An. petragnani and if the investigated rock pool breeding sites represent typical habitats of this species in temperate regions in Central Europe. [ABSTRACT FROM AUTHOR]

Objective: To assess HIV-1 isolate based resistance profiles from extensively pretreated patients and effects of a resistance guided switch of antiretroviral therapy.Methods: In a prospective study phenotypic and genotypic resistance analyses were performed on HIV infected individuals with failure of the current therapy and history of at least three antiretroviral regimens. Antiretroviral therapy was changed according to the results. Viral load and CD4 lymphocyte counts were measured at baseline, after 10 (SD 2), and 24 (2) weeks.Results: All patients (n=52) failed their actual regimen. Currently versus ever previously taking the specific drug, resistance associated mutations and phenotypic resistance to AZT and 3TC were found in over 80% of individuals; resistance to DDI and D4T was detected in less than 10% of cases. A resistance guided switch of therapy was followed by a median decrease of viral load of 0.5 log10 units after 24 weeks. Individuals resistant to two or more drugs compared with patients with resistance to less than two drugs of ongoing treatment, were switched to a regimen containing DDI, D4T, and a PI or NNRTI. After 10 (SD 2) weeks viral load decrease was pronounced in patients with resistance to at least two drugs in the previous regimen.Conclusions: Among different RTI, the profile of clinically relevant resistance indicates pronounced differences when looking at separate drugs. Regarding virological response, in the context of available drugs, resistance tested with currently used methods is of limited value in extensively pretreated patients and seems to have its value primarily in first or second switch of therapy. [ABSTRACT FROM AUTHOR]

The emergence of SARS-CoV-2 variants, as observed with the D614G spike protein mutant and, more recently, with B.1.1.7 (501Y.V1), B.1.351 (501Y.V2) and B.1.1.28.1 (P.1) lineages, represent a continuous threat and might lead to strains of higher infectivity and/or virulence. We report on the occurrence of a SARS-CoV-2 haplotype with nine mutations including D614G/T307I double-mutation of the spike. This variant expanded and completely replaced previous lineages within a short period in the subantarctic Magallanes Region, southern Chile. The rapid lineage shift was accompanied by a significant increase of cases, resulting in one of the highest incidence rates worldwide. Comparative coarse-grained molecular dynamic simulations indicated that T307I and D614G belong to a previously unrecognized dynamic domain, interfering with the mobility of the receptor binding domain of the spike. The T307I mutation showed a synergistic effect with the D614G. Continuous surveillance of new mutations and molecular analyses of such variations are important tools to understand the molecular mechanisms defining infectivity and virulence of current and future SARS-CoV-2 strains. [ABSTRACT FROM AUTHOR]

Summary: Objectives: To analyze the prevalence of hepatitis B virus (HBV) co-infection and its influence on mortality and treatment outcome within a large AIDS cohort in Chile. Methods: Clinical and epidemiological data from the Chilean AIDS Cohort were retrospectively analyzed. Adult patients tested for hepatitis B surface antigen (HBsAg) during the time period of October 2001 to October 2007 were included. Results: Of 5115 cohort patients, 1907 met the inclusion criteria. The prevalence of HBV co-infection was 8.4%. Overall mortality rates were 2.15 and 1.77 per 100 person-years for HBsAg-positive and HBsAg-negative HIV patients, respectively, with a mortality rate ratio of 1.22 (95% confidence interval 0.58–2.54). Kaplan–Meier survival and Cox regression analysis did not show significant differences between the groups. Virological and immunological responses to antiretroviral therapy (ART) were not influenced by HBsAg status, but in co-infected patients, initial ART was more frequently changed. Conclusions: The prevalence of hepatitis B co-infection was 8.4%, indicating a markedly elevated hepatitis B risk compared to the general population in Chile. Neither treatment outcome nor overall mortality was influenced by hepatitis B co-infection. Still, patients with hepatitis B co-infection had less stable ART regimens, which might be related to a higher risk of hepatotoxic drug effects. [ABSTRACT FROM AUTHOR]

Background: Strongyloidiasis is caused by a neglected nematode, manifesting as chronic intestinal infection with potentially severe manifestations. The disease is an emerging problem in non-endemic countries affecting travelers and migrants. Diagnosis of strongyloidiasis is hampered by the lack of standardization and absence of a gold standard. Since adequate direct methods to detect the motile larvae in stool samples are not widely available, other techniques such as serology have been developed., Methods: We evaluated three commercial ELISA kits (DRG Instruments, IVD Research, and Bordier Affinity Products) to detect IgG antibodies against Strongyloides stercoralis assays utilizing serum samples from travelers with microscopically confirmed strongyloidiasis (n = 50) and other imported helminthic infections (n = 159) as well as healthy controls (n = 50)., Results: The DRG, IVD, and Bordier assays showed sensitivities of 58.0%, 64.0%, and 56.0%, respectively. Specificity values were 96.0%, 96.0%, and 92.0% in healthy controls, and 67.3%, 62.9%, and 76.7% in cases with other helminth infections, respectively. Cross-reactions were mostly observed in cases with other nematodes (37.5%, 42.5%, and 20.0%, respectively), but also in trematode (33.3%, 38.1%, and 19.0%, respectively) and in cestode infections (25.0%, 30.0%, and 32.5%, respectively)., Conclusion: The study demonstrates the diagnostic limitations of serological assays to detect or exclude cases of strongyloidiasis in returning travelers, who frequently present with recent or acute infections., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Weitzel et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Background: Prolonged diarrhoea is common amongst returning travellers and is often caused by intestinal protozoa. However, the epidemiology of travel-associated illness caused by protozoal pathogens is not well described., Methods: We analysed records of returning international travellers with illness caused by Giardia duodenalis, Cryptosporidium spp., Cyclospora cayetanensis or Cystoisospora belli, reported to the GeoSentinel Network during January 2007-December 2019. We excluded records of travellers migrating, with an unascertainable exposure country, or from GeoSentinel sites that were not located in high-income countries., Results: There were 2517 cases, 82.3% giardiasis (n = 2072), 11.4% cryptosporidiosis (n = 287), 6.0% cyclosporiasis (n = 150) and 0.3% cystoisosporiasis (n = 8). Overall, most travellers were tourists (64.4%) on long trips (median durations: 18-30 days). Cryptosporidiosis more frequently affected people < 18 years (13.9%) and cyclosporiasis affected people ≥ 40 years (59.4%). Giardiasis was most frequently acquired in South Central Asia (45.8%) and sub-Saharan Africa (22.6%), cryptosporidiosis in sub-Saharan Africa (24.7%) and South-Central Asia (19.5%), cyclosporiasis in South East Asia (31.3%) and Central America (27.3%), and cystoisosporiasis in sub-Saharan Africa (62.5%). Cyclosporiasis cases were reported from countries of uncertain endemicity (e.g. Cambodia) or in countries with no previous evidence of this parasite (e.g. French Guiana). The time from symptom onset to presentation at a GeoSentinel site was the longest amongst travellers with giardiasis (median: 30 days). Over 14% of travellers with cryptosporidiosis were hospitalized., Conclusions: This analysis provides new insights into the epidemiology and clinical significance of four intestinal protozoa that can cause morbidity in international travellers. These data might help optimize pretravel advice and post-travel management of patients with travel-associated prolonged gastrointestinal illnesses. This analysis reinforces the importance of international travel-related surveillance to identify sentinel cases and areas where protozoal infections might be undetected or underreported., (© The Author(s) 2024. Published by Oxford University Press on behalf of International Society of Travel Medicine. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: The effect of clothing colour on the biting rates of different vector mosquito species is not well understood. Studies under tropical field conditions are lacking. This study aimed to determine the influence of clothing colours on mosquito biting rates in rural and suburban settings in West Africa., Methods: We performed a simulated field study in a suburban and a rural site in Mali using Mosquito-Magnet traps utilizing CO2 and other attractants, which were covered with black, white, and black/white striped textile sheets covers. These targets operated continuously for 10 consecutive days with bright nights (around full moon) and 10 consecutive days with dark nights (around new moon). Trapped mosquitoes were collected and catch rates counted hourly. Mosquitoes were morphologically identified to the species complex level (Anopheles gambiae s.l. and Culex pipiens s.l.) or species level (Aedes aegypti). A subset of Anopheles specimens were further identified by molecular methods., Results: Under bright-night conditions, An. gambiae s.l. was significantly more attracted to black targets than to white and striped targets; during dark nights, no target preference was noted. During bright nights, Cx. pipiens s.l. was significantly more attracted to black and striped targets than to white targets; a similar trend was noted during dark nights (not significant). For day-active Ae. aegypti, striped targets were more attractive than the other targets and black were more attractive than white targets., Conclusions: The study firstly demonstrated that under field conditions in Mali, West Africa, mosquito catch rates were influenced by different clothing colours, depending on mosquito species and light conditions. Overall, light colours were least attractive to host-seeking mosquitoes. Using white or other light-coloured clothing can potentially reduce bite exposure and risk of disease transmission in endemic tropical regions., (© The Author(s) 2024. Published by Oxford University Press on behalf of International Society of Travel Medicine. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Campylobacter is the leading cause of bacterial gastroenteritis worldwide and an emerging and neglected pathogen in South America. This zoonotic pathogen colonizes the gastrointestinal tract of a wide range of mammals and birds, with poultry as the most important reservoir for human infections. Apart from its high morbidity rates, the emergence of resistant strains is of global concern. The aims of this work were to determine genetic diversity, presence of antimicrobial resistance determinants and virulence potential of Campylobacter spp. isolated from patients with acute gastrointestinal disease at 'Clinica Alemana', Santiago de Chile. The study considered the isolation of Campylobacter spp., from stool samples during a 20-month period (January 2020 to September 2021). We sequenced (NextSeq, Illumina) and performed an in-depth analysis of the genome sequences of 88 Campylobacter jejuni and 2 Campylobacter coli strains isolated from clinical samples in Chile. We identified a high genetic diversity among C. je juni strains and the emergence of prevalent clonal complexes, which were not identified in our previous reports. While ~40% of strains harbored a mutation in the gyrA gene associated with fluoroquinolone resistance, no macrolide-resistance determinants were detected. Interestingly, gene clusters encoding virulence factors such as the T6SS or genes associated with long-term sequelae such as Guillain-Barré syndrome showed lineage-relatedness. In addition, our analysis revealed a high degree of variability regarding the presence of fT3SS and T6SS effector proteins in comparison to type strains 81-176, F38011, and NCTC 11168 and 488. Our study provides important insights into the molecular epidemiology of this emerging foodborne pathogen. In addition, the differences observed regarding the repertoire of fT3SS and T6SS effector proteins could have an impact on the pathogenic potential and transmissibility of these Latin American isolates, posing another challenge in characterizing the infection dynamics of this emergent and neglected bacterial pathogen., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Katz, Porte, Weitzel, Varela, Muñoz-Rehbein, Ugalde, Grim, González-Escalona, Blondel and Bravo.)

Competing Interests: All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. Thomas Weitzel, Constanza Martínez-Valdebenito, Katia Abarca, and Gerardo Acosta-Jamett report institutional support (including equipment and laboratory materials for diagnostic testing), travel support, and honoraria from the National Research and Development Agency of Chile (Agencia Nacional de Investigación y Desarrollo) and the National Fund for Scientific and Technological Development (Fondo Nacional de Desarrollo Científico y Tecnológico). No other potential conflicts of interest were disclosed.

Campylobacter spp. are considered the most frequent cause of acute gastroenteritis worldwide. However, outside high-income countries, its burden is poorly understood. Limited published data suggest that Campylobacter prevalence in low- and middle-income countries is high, but their reservoirs and age distribution are different. Culturing Campylobacter is expensive due to laboratory equipment and supplies needed to grow the bacterium (e.g., selective culture media, microaerophilic atmosphere, and a 42°C incubator). These requirements limit the diagnostic capacity of clinical laboratories in many resource-poor regions, leading to significant underdiagnosis and underreporting of isolation of the pathogen. CAMPYAIR, a newly developed selective differential medium, permits Campylobacter isolation without the need for microaerophilic incubation. The medium is supplemented with antibiotics to allow Campylobacter isolation in complex matrices such as human feces. The present study aims to evaluate the ability of the medium to recover Campylobacter from routine clinical samples. A total of 191 human stool samples were used to compare the ability of CAMPYAIR (aerobic incubation) and a commercial Campylobacter medium (CASA, microaerophilic incubation) to recover Campylobacter . All Campylobacter isolates were then identified by MALDI-TOF MS. CAMPYAIR showed sensitivity and specificity values of 87.5% (95% CI 47.4%-99.7%) and 100% (95% CI 98%-100%), respectively. The positive predictive value of CAMPYAIR was 100% and its negative predictive value was 99.5% (95% CI 96.7%-99.9%); Kappa Cohen coefficient was 0.93 (95% CI 0.79-1.0). The high diagnostic performance and low technical requirements of the CAMPYAIR medium could permit Campylobacter culture in countries with limited resources., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Levican, Varela, Porte, Weitzel, Briceño, Guerra, Mena and Hinton.)

Campylobacter spp. is an emerging cause of infectious diarrhea worldwide. In South American countries such as Chile, its prevalence is underestimated due to inadequate detection methods. Gastrointestinal multiplex PCR panels (GMP) permit rapid and sensitive detection of bacterial pathogens and provide important epidemiological information. This study aimed to analyze Campylobacter epidemiology using the results of molecular methods and to compare molecular detection results to those of culture methods. We performed a retrospective, descriptive analysis of Campylobacter spp. detected in clinical stool samples between 2014-2019 by GMP and culture. Within 16,582 specimens examined by GMP, Campylobacter was the most prevalent enteropathogenic bacteria (8.5%), followed by Salmonella spp. (3.9%), Shigella spp./enteroinvasive Escherichia coli (EIEC) (1.9%), and Yersinia enterocolitica (0.8%). The highest Campylobacter prevalence occurred in 2014/2015. Campylobacteriosis affected more males (57.2%) and adults from 19-65 years (47.9%) and showed a bimodal seasonality with summer and winter peaks. In 11,251 routine stool cultures, Campylobacter spp. was detected in 4.6%, mostly C. jejuni (89.6%). Among 4533 samples tested by GMP and culture in parallel, GMP showed a superior sensitivity (99.1% versus 50%, respectively). The study suggests that Campylobacter spp. is the most frequent bacterial enteropathogen in Chile.

Background: Scrub typhus is a potentially severe infection caused by bacteria of the genus Orientia, endemic in Asia-Pacific and recently discovered in southern Chile. The presented study aimed to determine the prevalence and species richness of rodent-associated trombiculid mites and their infection with Orientia spp. in different areas of two regions in southern Chile., Methodology/principal Findings: During summer 2020, trombiculid mites were collected from rodents captured in three areas in southern Chile known to be endemic for scrub typhus (Cochamó and Chiloé Island in the Los Lagos Region and Tortel in the Aysén Region). A total of 132 rodents belonging to five species were captured using Sherman-like traps; 89.4% were infested with trombiculids. Mite specimens were morphologically identified and subsequently tested by Orientia-specific qPCR. Six mite species were identified. Among chigger-infested rodents, 33.9% carried Orientia-positive mites; this rate was higher in Tortel (63.8%) than in Cochamó (45.0%) and Chiloé Island (2.0%). The analysis of individual mites (n = 901) revealed that 31.2% of Herpetacarus antarctica samples (n = 202) were positive for Orientia DNA; the prevalence was 7.0% in Paratrombicula neuquenensis (n = 213), 6.9% in Herpetacarus eloisae (n = 144), 3.6% in Argentinacarus expansus (n = 55), and 0% in Paratrombicula goffi (n = 110) and Quadraseta chiloensis (n = 177). The southernmost site (Tortel) showed the highest rates of trombiculid infestation, trombiculid load, and Orientia infection in the captured rodents., Conclusions/significance: Our study provides new insights into the trombiculid fauna and prevalence of Orientia in mites collected from wild rodents in southern Chile. Orientia DNA was detected in four of the six mite species. Rates of infestation, mite loads, and Orientia prevalences differed geographically and were highest in the Aysén Region. Our data improve our knowledge on possible vectors of scrub typhus and their distribution in Chile., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2023 Silva de la Fuente et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

The exposure of a research team to chigger mites in southern Chile allowed the first identification of a trombiculid species as vector and reservoir of scrub typhus outside the tsutsugamushi triangle, providing unique insights into the ecology and transmission of this recently discovered rickettsial infection in South America., (© The Author(s) 2021. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.)

Scrub typhus is a potentially severe rickettsiosis, caused by Orientia tsutsugamushi in the Asia-Pacific region. Recently, however, two distinct pathogens, " Candidatus Orientia chuto" and " Candidatus Orientia chiloensis", have been discovered in the Middle East and South America, respectively. Since the novel pathogens differ significantly from O. tsutsugamushi , many established diagnostic methods are unreliable. This work describes the development and validation of a new quantitative real-time PCR (qPCR) assay (Orien16S) for the detection of all known Orientia species. Based on a 94 bp sequence of the 16S rRNA gene ( rrs ), Orien16S recognized DNA samples from O. tsutsugamushi ( n = 41), Ca. O. chiloensis ( n = 5), and Ca. O. chuto ( n = 1), but was negative for DNA preparations from closely related rickettsiae and other members of the order Rickettsiales ( n = 22) as well as unrelated bacterial species ( n = 11). After its implementation in Chile, the assay was verified, correctly identifying all tested eschar and buffy coat samples ( n = 28) of clinical suspected cases. Furthermore, Orien16S detected Orientia DNA in trombiculid mites collected in endemic regions in southern Chile. The presented novel qPCR assay provides a useful tool for detecting Orientia and diagnosing scrub typhus from all geographical regions., Competing Interests: JJ and AR are employed by the Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Jiang, Martínez-Valdebenito, Weitzel, Farris, Acosta-Jamett, Abarca and Richards.)

Background: Healthcare workers (HCWs) are at high risk of exposure to SARS-CoV-2. Cross-sectional studies have provided variable rates of seroprevalence in HCWs. Longitudinal assessments of the serological response to Covid-19 among HCWs are crucial to understanding the risk of infection and changes in antibody titers over time. We aimed to investigate seroprevalence and risk factors associated with seroconversion in a prospective cohort of HCWs during the peak of the first wave of the Covid-19 pandemic., Methods: We conducted a longitudinal study among 446 front-line HCWsin a tertiary-care hospital in Chile from April to July 2020. IgG was determined monthly using two different ELISAs in serum samples of HCWs, during the three-month period. In each visit, demographic data, symptoms, risk factors, and exposure risks were also assessed., Results: The overall seroprevalence at the end of the study period was 24% (95% CI20.2-28.3), with 43% of seropositive HCWs reporting no prior symptoms. Seroconversion rates significantly differed over the study period, from 2.1% to as high as 8.8% at the peak of the epidemic. There were no statistically significant differences observed between HCWs in direct clinical care of patients with Covid-19 and those working in low risk areas. Antibody titers appeared to wane over time., Conclusions: HCWs were severely affected with a high rate of seroconversion that appeared to mirror the local epidemiological situation. A significant amount of participants underwent an asymptomatic infection, highlighting the need for improved surveillance policies. Antibody titers appear to wane over time; further studies to understand this finding's impact on the risk of reinfection are warranted.

In November 2018, we diagnosed a cluster of falciparum malaria cases in three Chilean travelers returning from Nigeria. Two patients were treated with sequential intravenous artesunate plus oral atovaquone/proguanil (AP) and one with oral AP. The third patient, a 23-year-old man, presented with fever on day 29 after oral AP treatment and was diagnosed with recrudescent falciparum malaria. The patient was then treated with oral mefloquine, followed by clinical recovery and resolution of parasitemia. Analysis of day 0 and follow-up blood samples, collected on days 9, 29, 34, 64, and 83, revealed that parasitemia had initially decreased but then increased on day 29. Sequencing confirmed Tyr268Cys mutation in the cytochrome b gene, associated with atovaquone resistance, in isolates collected on days 29 and 34 and P. falciparum dihydrofolate reductase mutation Asn51Ile, associated with proguanil resistance in all successfully sequenced samples. Molecular characterization of imported malaria contributes to clinical management in non-endemic countries, helps ascertain the appropriateness of antimalarial treatment policies, and contributes to the reporting of drug resistance patterns from endemic regions.

Background: Real-Time Reverse-Transcription Polymerase Chain Reaction (RT-PCR) is currently the only recommended diagnostic method for SARS-CoV-2. However, rapid immunoassays for SARS-CoV-2 antigen could significantly reduce the COVID-19 burden currently weighing on laboratories around the world., Methods: We evaluated the performance of two rapid fluorescence immunoassays (FIAs), SOFIA SARS Antigen FIA (Quidel Corporation, San Diego, CA, USA) and STANDARD F COVID-19 Ag FIA (SD Biosensor Inc., Gyeonggi-do, Republic of Korea), which use an automated reader. The study used 64 RT-PCR characterized clinical samples (32 positive; 32 negative), which consisted of nasopharyngeal swabs in universal transport medium., Results: Of the 32 positive specimens, all from patients within 5 days of symptom onset, the Quidel and SD Biosensor assays detected 30 (93.8%) and 29 (90.6%) samples, respectively. Among the 27 samples with high viral loads (Ct ≤ 25), the two tests had a sensitivity of 100%. Specificity was 96.9% for both kits., Conclusion: The high performance of the evaluated FIAs indicates a potential use as rapid and PCR-independent tools for COVID-19 diagnosis in early stages of infection. The excellent sensitivity to detect cases with viral loads above ~10 6 copies/mL (Ct values ≤ 25), the estimated threshold of contagiousness, suggests that the assays might serve to rapidly identify infective individuals., Competing Interests: The authors declare that they have no competing interests., (© 2021 Porte et al.)

In recent years, the spectrum and epidemiology of human rickettsioses has become an emerging topic in Chile. This survey aimed to assess the seroprevalence of spotted fever group rickettsiae (SFGR), typhus group rickettsiae (TGR), and scrub typhus group orientiae (STGO) in northern, central, and southern Chile. We performed a cross-sectional study of healthy adults in rural and urban settings of five regions. Participants were chosen by double stratified random sampling in urban and by convenience in rural locations (n = 1302). Serum specimens were analyzed for group-specific IgG antibodies against SFGR, TGR, and STGO by enzyme-linked immunosorbent assays (ELISAs). Overall seroprevalences to SFGR, TGR, and STGO were 5.3 %, 1.2 %, and 0.4 %, respectively. Prevalences showed geographical differences. Statistical analyses revealed an association of older age with seropositivity to SFGR and to TGR and of rural setting and male gender with seropositivity to SFGR. The study indicates that SFGR, TGR, and STGO are endemic in Chile. The very low STGO seroprevalence might indicate an insufficient sensitivity of serological tests using Asian O. tsutsugamushi strains as ELISA antigens for the detection of antibodies against Chilean Orientia species., (Copyright © 2020 Elsevier GmbH. All rights reserved.)

Objective: To analyse the spectrum, vaccination needs and pretravel advice complexity of travellers presenting at a travel medicine clinic in Santiago, Chile., Design: Cross-sectional study., Setting: Pretravel consultations in a private healthcare centre in Chile, an 'emerging market' country in South America., Participants: Travellers (n=1341) seeking pretravel advice at the Travel Medicine Program of Clínica Alemana, Santiago, from April 2016 to March 2018., Primary and Secondary Outcome Measures: Demographical and travel characteristics, indications for travel vaccines and malaria prophylaxis, and complexity of travel consultations., Results: Of 1341 travellers, 51% were female; the median age was 33 years. Most frequent travel reasons were tourism (67%) and business (20%). Median travel duration and time to departure were 21 days and 28 days, respectively. Most destinations were located in America (41%), followed by Asia (36%) and Africa (26%); 96% visited less developed countries, mostly in tropical regions, with risk of arboviral infections (94%) and malaria (69%). The indicated vaccine indications comprised hepatitis A (84%), yellow fever (58%), typhoid fever (51%), rabies (29%), polio (8%), Japanese encephalitis (6%) and meningococcal meningitis (5%). More than 60% of consultations were classified as complex., Conclusion: The studied population mostly visited less developed tropical regions, resulting in a high requirement of yellow fever and other travel-related vaccinations. Most consultations were complex and required a comprehensive knowledge and training in travel medicine., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2020. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Competing Interests: The authors have declared that no competing interests exist.

Campylobacter species are the leading cause of gastroenteritis worldwide and an emerging threat in developing countries. Here, we report the draft whole-genome sequences of 51 Campylobacter jejuni and 12 Campylobacter coli strains isolated from patients with gastroenteritis in Santiago, Chile.

Background: Coinfections of HIV patients with hepatitis B virus (HBV) and hepatitis C virus (HCV) are mayor public health problems, contributing to the emerging burden of HIV-associated hepatic mortality. Coinfection rates vary geographically, depending on various factors such as predominant transmission modes, HBV vaccination rates, and prevalence of HBV and HCV in the general population. In South America, the epidemiology of coinfections is uncertain, since systematic studies are scarce. Our study aimed to analyze rates of HBV and HCV infection in people living with HIV attending centers of the public and private health system in Chile., Methods: We performed a cross-sectional study including a public university hospital and a private health center in Santiago, Metropolitan Region in Chile. Serum samples were used to determine serological markers of hepatitis B (HBsAg, anti-HBs, anti-HBc total, HBeAg, anti-HBe) and anti-HCV. Demographic, clinical and laboratory data were obtained from medical records., Results: 399 patients were included (353 from public, 46 from private health center). Most (92.8%) were male, with a median age of 38.3 years; 99.4% acquired HIV through sexual contact (75.0% MSM); 25.7% had AIDS and 90.4% were on ART. In 78.9%, viral loads were <40 cps/mL; the median CD4 cell count was 468 cells/mm3. According to their serological status, 37.6% of patients were HBV naïve (susceptible), 6.5% were vaccinated, 43.6% had resolved HBV infection, and 5.8% were chronically infected. The rate of vaccination was 4.5% in the public and 21.7% in the private system. HCV coinfection was found in 1.0% of all patients., Conclusion: HBV coinfection rate was within the range of other South American countries, but lower than in non-industrialized regions in Asia and Africa. A low percentage of patients were HBV vaccinated, especially within the public system. HCV coinfection rate was very low, most probably due to the rareness of injecting drug use., Competing Interests: The authors have declared that no competing interests exist.

Gnathostomiasis is an emerging disease in non-endemic countries. This zoonotic nematode requires aquatic freshwater environments to complete its life cycle where larvae get encrusted in fishes. Typically, the infection manifests as migratory subcutaneous lesion caused by the larvae trak, which produces an eosinophilic panniculitis. Here we describe a patient who presented a migratory lesion with no response to antimicrobial therapy, a careful travel and food history together with specific laboratory tests led to the correct diagnosis. Gnathostomiasis should be suspected in patients with migratory skin lesions who have consumed raw freshwater fish during travel to endemic countries in South America or Asia.

Endemic scrub typhus was recently detected on Chiloé Island in southern Chile. We report a series of cases, acquired over a wide geographical range in continental Chile during 2016-2018, demonstrating that this emerging rickettsial infection is also found on the mainland of South America.

Malaria is one of the most severe health problems facing the world today. Until the mid-twentieth century, Europe was an endemic area of malaria, with the Balkan countries being heavily infested. Sibling species belonging to the Anopheles maculipennis complex are well-known as effective vectors of Plasmodium in Europe. A vast number of human malaria cases in the past in the former Yugoslavia territory have stressed the significance of An. maculipennis complex species as primary and secondary vectors. Therefore, the present study evaluates the species composition, geographic distribution and abundance of these malaria vector species. Mosquitoes were collected in the northern Serbian province of Vojvodina and analysed by PCR-RFLP, multiplex PCR and sequencing of the ITS2 intron of genomic rDNA. Four sibling species of the An. maculipennis complex were identified. Both larvae and adults of the recently described species An. daciae were identified for the first time in Serbia. In 250 larval samples, 109 (44%) An. messeae, 90 (36%) An. maculipennis s.s., 33 (13%) An. daciae and 18 (7%) An. atroparvus were identified. In adult collections, 81 (47%) An. messeae, 55 (32%) An. daciae, 33 (19%) An. maculipennis s.s., and 3 (2%) An. atroparvus were recorded. The most abundant species in Vojvodina was An. messeae, whereas An. atroparvus was confirmed a rare species in all parts. Since this species is a potentially, highly competent malarial vector, low population density could be crucial to prevent a new establishment of endemic malaria transmission in Serbia.

Background: Chikungunya (CHIK) was introduced in The Americas in 2013, spreading rapidly. In 2014, the first imported case was diagnosed in Chile., Aim: To identify patients with clinical suspicion of CHIK and describe their clinical and laboratory characteristics., Patients and Methods: Patients with suspected CHIK were enrolled. All were confirmed by PCR, IgM or IgG CHIK. A structured survey was applied, which included demographic questions, travel characteristics, clinical manifestations, and laboratory results., Results: 21 patients were enrolled and CHIK was confirmed in 16, who were further analyzed; 12 were female (75%), average age 39 years (27-52). The Caribbean and South Americawere the most frequent sites of exposure. In 63%, the initial symptom was arthralgia. Most frequent symptoms were myalgias, malaise (both 100%), fever, and polyarthralgia (both 94%). The median duration of arthralgias was 90 days (3-262); in 53% arthralgias lasted ≥ 3 months. Main joints involved were ankles, hands, and wrists; 87% reported invalidating pain. Arthritis lasted longer in men than in women (p < 0.001). 38% of patients presented lymphopenia and one patient mild thrombocytopenia. Two patients required hospitalization, one with severe headaches, the other with acute pyelonephritis., Conclusions: Chikungunya should be suspected in returning travelers presenting with fever and severe polyarthralgia. Travelers to endemic areas should apply prevention measures to avoid mosquito bites.

The presented study analyzed the presence and geographical distribution of the tropical and temperate lineages of Rhipicephalus sanguineus sensu lato in Chile. R. sanguineus s.l. ticks were collected from dogs at 14 sites in northern and central Chile for morphological and genetic analysis based on the 16S rDNA gene. Phylogenetic studies proved the existence of both, the tropical and the temperate lineages. The former was represented by a single haplotype and occurred in the far north; the latter included four haplotypes and was observed from the Tarapacá Region southwards. In four sites at latitudes from 20°S to 22°S, both lineages were found to coexist. Our study discovered for the first time the existence of the tropical lineage in Chile and demonstrated that distributions of the tropical and temperate lineages overlap, forming a transitional zone of approximately 200 km in northern coastal Chile., (Copyright © 2018 Elsevier GmbH. All rights reserved.)