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Browsing by Author "Weitzel, Thomas"

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Absence of convincing evidence of Coxiella burnetii infection in Chile: a cross-sectional serosurvey among healthy adults in four different regions
(2016) Weitzel, Thomas; López, Javier; Acosta-Jamett, Gerardo; Edouard, Sophie; Parola, Philippe; Abarca Villaseca, Katia
Abstract Background Coxiella burnetii is an important zoonotic pathogen of global distribution. Still, in most parts of South America including Chile, systematic epidemiological data are lacking. The presented study aims to determine the seroprevalence of Coxiella burnetii antibodies in healthy adults of four different regions in Chile. Methods A cross-sectional study was performed, which included healthy adults living in rural and urban areas of four cities located in different regions in northern, central, and southern Chile. In urban sectors, households were chosen by double stratified random sampling, while in rural areas convenience sampling was performed. Serum specimens were taken and screened for the presence of IgG antibodies against C. burnetii phase II antigen using a commercial ELISA kit. Positive and indeterminate results were confirmed by a reference laboratory using indirect immunofluorescence assay (IFA). Results A total of 1112 individuals were included. Of those, 8 were positive by ELISA, but only one sample was confirmed using IFA. Statistical analysis for population freedom from disease revealed a high probability that C. burnetii was absent in our study population. Conclusion Our work provides the first epidemiological data on human Q fever in Chile indicating either a very low endemicity or the absence of this pathogen in the studied areas.Abstract Background Coxiella burnetii is an important zoonotic pathogen of global distribution. Still, in most parts of South America including Chile, systematic epidemiological data are lacking. The presented study aims to determine the seroprevalence of Coxiella burnetii antibodies in healthy adults of four different regions in Chile. Methods A cross-sectional study was performed, which included healthy adults living in rural and urban areas of four cities located in different regions in northern, central, and southern Chile. In urban sectors, households were chosen by double stratified random sampling, while in rural areas convenience sampling was performed. Serum specimens were taken and screened for the presence of IgG antibodies against C. burnetii phase II antigen using a commercial ELISA kit. Positive and indeterminate results were confirmed by a reference laboratory using indirect immunofluorescence assay (IFA). Results A total of 1112 individuals were included. Of those, 8 were positive by ELISA, but only one sample was confirmed using IFA. Statistical analysis for population freedom from disease revealed a high probability that C. burnetii was absent in our study population. Conclusion Our work provides the first epidemiological data on human Q fever in Chile indicating either a very low endemicity or the absence of this pathogen in the studied areas.Abstract Background Coxiella burnetii is an important zoonotic pathogen of global distribution. Still, in most parts of South America including Chile, systematic epidemiological data are lacking. The presented study aims to determine the seroprevalence of Coxiella burnetii antibodies in healthy adults of four different regions in Chile. Methods A cross-sectional study was performed, which included healthy adults living in rural and urban areas of four cities located in different regions in northern, central, and southern Chile. In urban sectors, households were chosen by double stratified random sampling, while in rural areas convenience sampling was performed. Serum specimens were taken and screened for the presence of IgG antibodies against C. burnetii phase II antigen using a commercial ELISA kit. Positive and indeterminate results were confirmed by a reference laboratory using indirect immunofluorescence assay (IFA). Results A total of 1112 individuals were included. Of those, 8 were positive by ELISA, but only one sample was confirmed using IFA. Statistical analysis for population freedom from disease revealed a high probability that C. burnetii was absent in our study population. Conclusion Our work provides the first epidemiological data on human Q fever in Chile indicating either a very low endemicity or the absence of this pathogen in the studied areas.
Canine seroprevalence to Orientia species in southern Chile: A cross-sectional survey on the Chiloe A Island
(2018) Weitzel, Thomas; Jiang, Ju; Acosta-Jamett, Gerardo; Martinez-Valdebenito, Constanza; Lopez, Javier; Richards, Allen L.; Abarca Villaseca, Katia
Catheter-associated bloodstream infection caused by Leifsonia aquatica in a haemodialysis patient: a case report
(SOC GENERAL MICROBIOLOGY, 2012) Porte, Lorena; Soto, Andres; Andrighetti, Daniela; Dabanch, Jeannette; Braun, Stephanie; Saldivia, Alejandra; Carlos Flores, Juan; Wozniak, Aniela; Garcia, Patricia; Weitzel, Thomas
Leifsonia aquatica is an aquatic coryneform rod that is capable of forming biofilms in environmental water sources. It has rarely been associated with human infections and its pathogenicity and clinical significance are uncertain. We describe a case of catheter-related bloodstream infection in a haemodialysis patient. The isolate grew on conventional media as a yellow-pigmented colony, but identification required molecular methods. Although the strain displayed reduced sensitivity to vancomycin, the clinical outcome was favourable after catheter removal and intravenous treatment with this antibiotic. Our report gives further evidence of the capability of this aquatic bacterium to cause human infection.
Chigger Mites (Acariformes: Trombiculidae) of Chiloe Island, Chile, With Descriptions of Two New Species and New Data on the Genus Herpetacarus
(2021) Carolina Silva-de La Fuente, Maria; Stekolnikov, Alexandr A.; Weitzel, Thomas; Beltrami, Esperanza; Martinez-Valdebenito, Constanza; Abarca, Katia; Acosta-Jamett, Gerardo
Three species of chigger mites are recorded in our collections from four species of cricetid rodents on Chiloe Island (southern Chile, Los Lagos Region), an area endemic to scrub typhus (Orientia sp.). Two species are described as new-Herpetacarus (Abonnencia) eloisae sp. nov. and Quadraseta chiloensis sp. nov. One species, Paratrombicula goffi Stekolnikov and Gonzalez-Acuna 2012, is for the first time recorded on a mammal host (one species of cricetid rodent), and its distribution is extended to the Los Lagos Region of Chile. The genus Proschoengastia Vercammen-Grandjean, 1967 is synonymized with the subgenus Herpetacarus (Abonnencia) Vercammen-Grandjean, 1960, and four new combinations are established: Herpetacarus (Abonnencia) herniosa (Brennan and Jones, 1961), comb. nov., Herpetacarus (Abonnencia) insolita (Brennan and Jones, 1961), comb. nov., Herpetacarus (Abonnencia) macrochaeta (Brennan and Jones, 1961), comb. nov., and Herpetacarus (Abonnencia) antarctica (Stekolnikov and Gonzalez-Acuna, 2015), comb. nov.
Chikungunya, enfermedad emergente en América Latina. Descripción de los primeros casos en Chile
(2018) Perret Pérez, Cecilia; Vizcaya Altamirano, María Cecilia; Weitzel, Thomas; Rosas, Reinaldo; Dabanch, Jeannette; Martínez, Constanza
Cluster of imported vivax malaria in travelers returning from Peru
(2015) Weitzel, Thomas; Labarca L., Jaime; Cortes, Claudia P.; Rosas, Reinaldo; Balcells Marty, María Elvira; Perret Pérez, Cecilia
Development of a New Genus-Specific Quantitative Real-Time PCR Assay for the Diagnosis of Scrub Typhus in South America
(2022) Jiang, Ju; Martinez-Valdebenito, Constanza; Weitzel, Thomas; Farris, Christina M.; Acosta-Jamett, Gerardo; Abarca, Katia; Richards, Allen L.
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.
Eco-epidemiology of rodent-associated trombiculid mites and infection with Orientia spp. in Southern Chile
(2023) Silva de la Fuente, Maria Carolina; Perez, Caricia; Martinez-Valdebenito, Constanza; Perez, Ruth; Vial, Cecilia; Stekolnikov, Alexandr; Abarca, Katia; Weitzel, Thomas; Acosta-Jamett, Gerardo
BackgroundScrub 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 findingsDuring summer 2020, trombiculid mites were collected from rodents captured in three areas in southern Chile known to be endemic for scrub typhus (Cochamo and Chiloe Island in the Los Lagos Region and Tortel in the Aysen 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 Cochamo (45.0%) and Chiloe 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/SignificanceOur 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 Aysen Region. Our data improve our knowledge on possible vectors of scrub typhus and their distribution in Chile.
Geographical distribution and phylogenetic analysis of rhipicephalus sanguineus sensu lato in northern and central Chile
(2018) Díaz Acevedo, Fabián Esteban; Martínez Valdebenito, Constanza; López, Javier; Weitzel, Thomas; Abarca Villaseca, Katia
Hosts and vectors of scrub typhus in Chile: epidemiological study and molecular analyses of Orientia infection in rodents and rodent-associated mites
(2024) Martínez Valdebenito, Constanza; Acosta-Jamett, Gerardo; Abello, Rayitray; Jiang, Ju; Richards, Allen L.; Abarca Villaseca, Katia; Weitzel, Thomas
Abstract Candidatus Orientia chiloensis causes scrub typhus over a wide geographical range in southern Chile. The life cycle, including vectors and reservoirs of this novel rickettsial pathogen, is incompletely understood. We analyzed rodent tissue and rodent-associated mite samples collected during a field study in six localities on Chiloé Island, where human scrub typhus cases have occurred. Using molecular methods, we detected Orientia DNA in 24.8% of rodents, belonging to five of seven captured species. Orientia-infection rates showed geographical variations, but were not influenced by rodent species, sex, age, and mite infestation. Phylogenetic analysis showed that Orientia sequences from trombiculid mites (Proschoengastia eloisae) were identical to those from scrub typhus patients from the same region. The results suggest that these rodent-associated mites serve as vectors and play an important role in the ecology of scrub typhus in southern Chile. Further studies are required to determine whether Orientia-infected rodents can also serve as reservoir of Orientia in Chile. Graphical Abstract
Cryptococcus bacillisporus (VGIII) Meningoencephalitis Acquired in Santa Cruz, Bolivia
(2021) Thompson, Luis; Porte, Lorena; Diaz, Violeta; Diaz, Maria Cristina; Solar, Sebastian; Valenzuela, Pablo; Norley, Nicole; Pires, Yumai; Carreno, Fernando; Valenzuela, Sergio; Shabani, Rukmane; Rickerts, Volker; Weitzel, Thomas
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.
Identification of trombiculid mites (Acari: Trombiculidae) on rodents from Chiloe Island and molecular evidence of infection with Orientia species
(2020) Acosta-Jamett, Gerardo; Martinez-Valdebenito, Constanza; Beltrami, Esperanza; Carolina Silva-de La Fuente, Maria; Jiang, Ju; Richards, Allen L.; Weitzel, Thomas; Abarca, Katia
Background
Imported scrub typhus: first case in South America and review of the literature
(2018) Weitzel, Thomas; Martínez Valdebenito, Constanza Pamela; Abarca Villaseca, Katia; Aylwin, Mabel; Jiang, Ju; Munita, Jose M.; Thompson, Luis; Richards, Allen L.
Abstract Background Scrub typhus is a neglected vector-borne zoonosis causing life-threatening illnesses, endemic in the Asian-Pacific region and, as recently discovered, in southern Chile. Scrub typhus is rarely reported in travelers, most probably due to the lack of clinical experience and diagnostic tests in non-endemic countries. We report the first case of imported scrub typhus in South America. Case presentation A 62-year-old tourist from South Korea presented severely ill with fever, rash, and eschar in Santiago, Chile. Laboratory exams showed thrombocytopenia and elevated inflammation parameters, hepatic enzymes, and LDH. With the clinical suspicion of scrub typhus, empirical treatment with doxycycline was initiated and the patient recovered rapidly and without complications. The diagnosis was confirmed by IgM serology and by real-time PCR, which demonstrated infection with Orientia tsutsugamushi (Kawasaki clade). Conclusions Only due to the emerging clinical experience with endemic South American scrub typhus and the recent implementation of appropriate diagnostic techniques in Chile, were we able to firstly identify and adequately manage a severe case of imported scrub typhus in South America. Physicians attending febrile travelers need to be aware of this rickettsiosis, since it requires prompt treatment with doxycycline to avoid complications.Abstract Background Scrub typhus is a neglected vector-borne zoonosis causing life-threatening illnesses, endemic in the Asian-Pacific region and, as recently discovered, in southern Chile. Scrub typhus is rarely reported in travelers, most probably due to the lack of clinical experience and diagnostic tests in non-endemic countries. We report the first case of imported scrub typhus in South America. Case presentation A 62-year-old tourist from South Korea presented severely ill with fever, rash, and eschar in Santiago, Chile. Laboratory exams showed thrombocytopenia and elevated inflammation parameters, hepatic enzymes, and LDH. With the clinical suspicion of scrub typhus, empirical treatment with doxycycline was initiated and the patient recovered rapidly and without complications. The diagnosis was confirmed by IgM serology and by real-time PCR, which demonstrated infection with Orientia tsutsugamushi (Kawasaki clade). Conclusions Only due to the emerging clinical experience with endemic South American scrub typhus and the recent implementation of appropriate diagnostic techniques in Chile, were we able to firstly identify and adequately manage a severe case of imported scrub typhus in South America. Physicians attending febrile travelers need to be aware of this rickettsiosis, since it requires prompt treatment with doxycycline to avoid complications.
Intestinal protozoa in returning travellers: a GeoSentinel analysis from 2007 to 2019
(2024) Weitzel, Thomas; Brown, Ashley; Libman, Michael; Perret, Cecilia; Huits, Ralph; Chen, Lin; Leung, Daniel T.; Leder, Karin; Connor, Bradley A.; Menendez, Marta D.; Asgeirsson, Hilmir; Schwartz, Eli; Salvador, Fernando; Malvy, Denis; Saio, Mauro; Norman, Francesca F.; Amatya, Bhawana; Duvignaud, Alexandre; Vaughan, Stephen; Glynn, Marielle; Angelo, Kristina M.
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.
Performance of the VITEK MS System for the Identification of Filamentous Fungi in a Routine Microbiological Laboratory in Chile
(2024) Porte, Lorena; Cruz, Rodrigo; Pérez, Inia; Varela, Carmen; Díaz, Cristina; García Cañete, Patricia; Legarraga, Paulette; Valdivieso, Francisca; Weitzel, Thomas
Background: Filamentous fungi are an emergent cause of severe infections in immunocompromised patients. Timely and accurate identification is crucial to initiate appropriate therapy. Traditional identification methods are time-consuming, labor-intensive, and operator-dependent. Ma-trix-assisted laser desorption/ionization-time-of-flight (MALDI-TOF) mass spectrometry is a rapid and easy-to-perform identification method. This study evaluates the effectiveness of a commercial MALDI-TOF MS platform to identify filamentous fungi in a routine laboratory. Material and Methods: We included 67 fungal isolates from 35 species/species complexes within 15 genera, confirmed in mycology reference laboratories. 33 were from clinical samples and 34 from strain collections. The study used the VITEK MS system (v3.2.0 database), after sample extraction by VITEK MS Mould Kit. Results were classified into categories: ‘correct species’, ‘correct species complex’, ‘correct genus’, ‘incorrect identification’, and ‘no identification’. We also evaluated the practicality of the kit. Results: VITEK MS correctly identified 91.0% of isolates (58.2% to species, 29.9% to species complex, and 1.5% to genus level). In 82%, the result matched the species/species complex identified by reference methods. No misidentifications were observed. The kit was rapid and easy to use. Conclusion: The VITEK MS system showed a high capability to accurately identify filamentous fungi in a routine laboratory.
Prevalence and Risk Factors for Echinococcal Infection in a Rural Area of Northern Chile : A Household-Based Cross-Sectional Study
(2014) Acosta Jamett, Gerardo; Weitzel, Thomas; Boufana, Belgees; Adones, Claudia; Bahamonde, Andrea; Abarca Villaseca, Katia; Craig, Philip S.; Reiter-Owona, Ingrid
Recomendaciones para viajeros chilenos a la Copa Mundial de la FIFA 2014 en Brasil
(2014) Perret Pérez, Cecilia; Weitzel, Thomas
Este artículo proporciona una serie de precauciones a observar y vacunas recomendadas para viajeros chilenos que asistirán a la Copa Mundial de Fútbol 2014 en Brasil. Su propósito es ayudar a los médicos a preparar a los visitantes a este masivo evento y resume las recomendaciones útiles para evitar enfermedades infecciosas, teniendo en consideración las circunstancias y disponibilidad en Chile.
Scrub Typhus in Continental Chile, 2016-2018
(2019) Weitzel, Thomas; Martinez-Valdebenito, Constanza; Acosta-Jamett, Gerardo; Jiang, Ju; Richards, Allen L.; Abarca, Katia
Endemic scrub typhus was recently detected on Chiloe 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.
Scrub Typhus Outbreak - Los Lagos Region, Chile, January-February 2023
(2023) Weitzel, Thomas; Martinez-Valdebenito, Constanza; Acosta-Jamett, Gerardo; Abarca, Katia
Yellow fever vaccination for Chilean tourists visiting Brazil. Practical considerations
(SOC CHILENA INFECTOLOGIA, 2018) Weitzel, Thomas; Perret, Cecilia; Valdivieso, Francisca; Abarca, Katia; Vial, Pablo
Due to the recent yellow fever outbreak affecting the costal region of Brazil, including main touristic destinations, there is a high demand of yellow fever vaccination. This publication addresses the most relevant practical issues regarding this vaccine for tourists visiting Brazil and aims to serve as a guideline for non-expert physicians in Chile and elsewhere.

Browsing by Author "Weitzel, Thomas"

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