SCRUB TYPHUS IN SOUTH AMERICA: EXPLORING THE CLINICAL AND EPIDEMIOLOGICAL CHARACTERISTICS OF AN EMERGING INFECTIOUS DISEASE IN SOUTHERN CHILE

Project Title

Partner Organisations

Facultad de Medicina Clínica Alemana Universidad del Desarrollo

Internal ID

1170810

Principal Investigator

WEITZEL, THOMAS

Publications

Now showing 1 - 10 of 14

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Scrub Typhus in Continental Chile, 2016–2018
(2019)
WEITZEL, THOMAS
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Constanza Martínez-Valdebenito
;
Gerardo Acosta-Jamett
;
Ju Jiang
;
Allen L. Richards
14Scopus© Citations 57
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Chigger Mites (Acariformes: Trombiculidae) of Chiloé Island, Chile, With Descriptions of Two New Species and New Data on the Genus<i>Herpetacarus</i>
(2020)
María Carolina Silva-de la Fuente
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Alexandr A Stekolnikov
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WEITZEL, THOMAS
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Esperanza Beltrami
;
Constanza Martínez-Valdebenito
<jats:title>Abstract</jats:title><jats:p>Three species of chigger mites are recorded in our collections from four species of cricetid rodents on Chiloé 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 goffiStekolnikov and González-Acuña 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 ProschoengastiaVercammen-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-Acuña, 2015), comb. nov.</jats:p>
1Scopus© Citations 18 1
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Molecular Description of a Novel <i>Orientia</i> Species Causing Scrub Typhus in Chile
(2020)
Katia Abarca
;
Constanza Martínez-Valdebenito
;
Jenniffer Angulo
;
Ju Jiang
;
Christina M. Farris
1Scopus© Citations 78 1
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Scrub typhus: A new cause of acute undifferentiated febrile illness in Latin America?
(2021)
Carlos Ramiro Silva-Ramos
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Fernando de Castro Jacinavicius
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WEITZEL, THOMAS
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David H. Walker
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Álvaro A. Faccini-Martínez
16Scopus© Citations 6
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Development of a New Genus-Specific Quantitative Real-Time PCR Assay for the Diagnosis of Scrub Typhus in South America
(2022)
Ju Jiang
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Constanza Martínez-Valdebenito
;
WEITZEL, THOMAS
;
Christina M. Farris
;
Gerardo Acosta-Jamett
<jats:p>Scrub typhus is a potentially severe rickettsiosis, caused by <jats:italic>Orientia tsutsugamushi</jats:italic> in the Asia-Pacific region. Recently, however, two distinct pathogens, “<jats:italic>Candidatus</jats:italic> Orientia chuto” and “<jats:italic>Candidatus</jats:italic> Orientia chiloensis”, have been discovered in the Middle East and South America, respectively. Since the novel pathogens differ significantly from <jats:italic>O. tsutsugamushi</jats:italic>, 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 <jats:italic>Orientia</jats:italic> species. Based on a 94 bp sequence of the 16S rRNA gene (<jats:italic>rrs</jats:italic>), Orien16S recognized DNA samples from <jats:italic>O. tsutsugamushi</jats:italic> (<jats:italic>n</jats:italic> = 41), <jats:italic>Ca.</jats:italic> O. chiloensis (<jats:italic>n</jats:italic> = 5), and <jats:italic>Ca.</jats:italic> O. chuto (<jats:italic>n</jats:italic> = 1), but was negative for DNA preparations from closely related rickettsiae and other members of the order Rickettsiales (<jats:italic>n</jats:italic> = 22) as well as unrelated bacterial species (<jats:italic>n</jats:italic> = 11). After its implementation in Chile, the assay was verified, correctly identifying all tested eschar and buffy coat samples (<jats:italic>n</jats:italic> = 28) of clinical suspected cases. Furthermore, Orien16S detected <jats:italic>Orientia</jats:italic> DNA in trombiculid mites collected in endemic regions in southern Chile. The presented novel qPCR assay provides a useful tool for detecting <jats:italic>Orientia</jats:italic> and diagnosing scrub typhus from all geographical regions.</jats:p>
1Scopus© Citations 14 1
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Canine seroprevalence to Orientia species in southern Chile: A cross-sectional survey on the Chiloe A Island
(2018)
Thomas Weitzel
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Ju Jiang
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Gerardo Acosta-Jamett
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Constanza Martínez-Valdebenito
;
Javier López
1Scopus© Citations 14 1
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Hosts and vectors of scrub typhus in Chile: epidemiological study and molecular analyses of Orientia infection in rodents and rodent-associated mites
(Springer Science and Business Media LLC, 2024-12-18)
Constanza Martínez-Valdebenito
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Gerardo Acosta-Jamett
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Rayitray Abello
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Ju Jiang
;
Allen L. Richards
<jats:title>Abstract</jats:title><jats:p><jats:italic>Candidatus</jats:italic> 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 <jats:italic>Orientia</jats:italic> DNA in 24.8% of rodents, belonging to five of seven captured species. <jats:italic>Orientia</jats:italic>-infection rates showed geographical variations, but were not influenced by rodent species, sex, age, and mite infestation. Phylogenetic analysis showed that <jats:italic>Orientia</jats:italic> sequences from trombiculid mites (<jats:italic>Proschoengastia eloisae</jats:italic>) 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 <jats:italic>Orientia</jats:italic>-infected rodents can also serve as reservoir of <jats:italic>Orientia</jats:italic> in Chile.</jats:p> <jats:p><jats:bold>Graphical Abstract</jats:bold></jats:p>
1Scopus© Citations 8
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Eco-epidemiology of rodent-associated trombiculid mites and infection with Orientia spp. in Southern Chile
(2023)
María Carolina Silva de la Fuente
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Caricia Pérez
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Constanza Martínez-Valdebenito
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Pérez Ball, Ruth
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VIAL COX, MARIA CECILIA
<jats:sec id="sec001"> <jats:title>Background</jats:title> <jats:p>Scrub typhus is a potentially severe infection caused by bacteria of the genus <jats:italic>Orientia</jats:italic>, 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 <jats:italic>Orientia</jats:italic> spp. in different areas of two regions in southern Chile.</jats:p> </jats:sec> <jats:sec id="sec002"> <jats:title>Methodology/Principal findings</jats:title> <jats:p>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 <jats:italic>Orientia</jats:italic>-specific qPCR. Six mite species were identified. Among chigger-infested rodents, 33.9% carried <jats:italic>Orientia</jats:italic>-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 <jats:italic>Herpetacarus antarctica</jats:italic> samples (n = 202) were positive for <jats:italic>Orientia</jats:italic> DNA; the prevalence was 7.0% in <jats:italic>Paratrombicula neuquenensis</jats:italic> (n = 213), 6.9% in <jats:italic>Herpetacarus eloisae</jats:italic> (n = 144), 3.6% in <jats:italic>Argentinacarus expansus</jats:italic> (n = 55), and 0% in <jats:italic>Paratrombicula goffi</jats:italic> (n = 110) and <jats:italic>Quadraseta chiloensis</jats:italic> (n = 177). The southernmost site (Tortel) showed the highest rates of trombiculid infestation, trombiculid load, and <jats:italic>Orientia</jats:italic> infection in the captured rodents.</jats:p> </jats:sec> <jats:sec id="sec003"> <jats:title>Conclusions/Significance</jats:title> <jats:p>Our study provides new insights into the trombiculid fauna and prevalence of <jats:italic>Orientia</jats:italic> in mites collected from wild rodents in southern Chile. <jats:italic>Orientia</jats:italic> DNA was detected in four of the six mite species. Rates of infestation, mite loads, and <jats:italic>Orientia</jats:italic> 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.</jats:p> </jats:sec>
1Scopus© Citations 9 2
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Novel Vector of Scrub Typhus in Sub-Antarctic Chile: Evidence From Human Exposure
(2021)
WEITZEL, THOMAS
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María Carolina Silva-de la Fuente
;
Constanza Martínez-Valdebenito
;
Alexandr A Stekolnikov
;
Caricia Pérez
<jats:title>Abstract</jats:title> <jats:p>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.</jats:p>
Scopus© Citations 22 5
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Human seroepidemiology of Rickettsia and Orientia species in Chile – A cross-sectional study in five regions
(2020)
WEITZEL, THOMAS
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Gerardo Acosta-Jamett
;
Ju Jiang
;
Constanza Martínez-Valdebenito
;
Christina M. Farris
11 1Scopus© Citations 11

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