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Surveillance of vector-borne infections: Dogs as sentinel animals for Orientia and Rickettsia exposure in five regions in Chile
(Elsevier BV, 2026-06)
Paulina López-Silva
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Constanza Martínez-Valdebenito
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Ju Jiang
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Katia Abarca
;
Javier López
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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SARS-CoV-2 infectivity and antigenic evasion: spotlight on isolated Omicron sub-lineages
(2024)
Aldo Barrera
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Constanza Martínez-Valdebenito
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Jenniffer Angulo
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Carlos Palma
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HORMAZABAL CASTILLO, JUAN PATRICIO
<jats:p>Since the SARS-CoV-2 outbreak in 2019, a diversity of viral genomic variants has emerged and spread globally due to increased transmissibility, pathogenicity, and immune evasion. By the first trimester of 2023 in Chile, as in most countries, BQ and XBB were the predominant circulating sub-lineages of Omicron. The molecular and antigenic characteristics of these variants have been mainly determined using non-authentic spike pseudoviruses, which is often described as a limitation. Additionally, few comparative studies using isolates from recent Omicron sub-lineages have been conducted. In this study, we isolated SARS-CoV-2 variants from clinical samples, including the ancestral B.1.1, Delta, Omicron BA.1, and sub-lineages of BA.2 and BA.5. We assessed their infectivity through cell culture infections and their antibody evasion using neutralization assays. We observed variations in viral plaque size, cell morphology, and cytotoxicity upon infection in Vero E6-TMPRSS2 cells for each variant compared to the ancestral B.1.1 virus. BA.2-derived sub-variants, such as XBB.1.5, showed attenuated viral replication, while BA.5-derived variants, such as BQ.1.1, exhibited replication rates similar to the ancestral SARS-CoV-2 virus. Similar trends were observed in intestinal Caco-2 cells, except for Delta. Antibody neutralization experiments using sera from individuals infected during the first COVID-19 wave (FWI) showed a consistent but moderate reduction in neutralization against Omicron sub-lineages. Interestingly, despite being less prevalent, BQ.1.1 showed a 6.1-fold greater escape from neutralization than XBB.1.5. Neutralization patterns were similar when tested against sera from individuals vaccinated with 3xBNT162b2 (PPP) or Coronavac-Coronavac-BNT162b2 (CCP) schedules. However, CCP sera showed 2.3-fold higher neutralization against XBB.1.5 than FWI and PPP sera. This study provides new insights into the differences between BA.2 and BA.5-derived variants, leading to their eventual outcompetition. Our analysis offers important evidence regarding the balance between infectivity and antigenic escape that drives the evolution of second-generation SARS-CoV-2 variants in the population.</jats:p>
5Scopus© Citations 3
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Viral shedding and viraemia of Andes virus during acute hantavirus infection: a prospective study
(2024)
Marcela Ferrés
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Constanza Martínez-Valdebenito
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Carolina Henriquez
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Claudia Marco
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Jenniffer Angulo
10Scopus© Citations 29
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Notes from the Field: Scrub Typhus Outbreak — Los Lagos Region, Chile, January–February 2023
(2023)
WEITZEL, THOMAS
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Constanza Martínez-Valdebenito
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Gerardo Acosta-Jamett
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Katia Abarca
6Scopus© Citations 4
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Scrub typhus in Tierra del Fuego: a tropical rickettsiosis in a subantarctic region
(2021)
WEITZEL, THOMAS
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AYLWIN RAMIREZ, MABEL CRISTINA
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Constanza Martínez-Valdebenito
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Gerardo Acosta-Jamett
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Katia Abarca
10Scopus© Citations 10
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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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Chigger Mites (Acariformes: Trombiculidae) of Chiloé Island, Chile, With Descriptions of Two New Species and New Data on the GenusHerpetacarus
(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
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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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Identification of trombiculid mites (Acari: Trombiculidae) on rodents from Chiloé Island and molecular evidence of infection with Orientia species
(2020)
Gerardo Acosta-Jamett
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Constanza Martínez-Valdebenito
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Esperanza Beltrami
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María Carolina Silva-de La Fuente
;
Ju Jiang
23 1Scopus© Citations 42
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Molecular Description of a Novel Orientia 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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