Universidad del Desarrollo

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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
;
Gerardo Acosta-Jamett
;
Rayitray Abello
;
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
;
Caricia Pérez
;
Constanza Martínez-Valdebenito
;
Pérez Ball, Ruth
;
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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A Single-Nucleotide Polymorphism of αVβ3 Integrin Is Associated with the Andes Virus Infection Susceptibility
(2019)
Constanza Martínez-Valdebenito
;
Jenniffer Angulo
;
Nicole Le Corre
;
Claudia Marco
;
VIAL COX, MARIA CECILIA
<jats:p>The Andes Orthohantavirus (ANDV), which causes the hantavirus cardiopulmonary syndrome, enters cells via integrins, and a change from leucine to proline at residue 33 in the PSI domain (L33P), impairs ANDV recognition. We assessed the association between this human polymorphism and ANDV infection. We defined susceptible and protective genotypes as “TT” (coding leucine) and “CC” (coding proline), respectively. TT was present at a rate of 89.2% (66/74) among the first cohort of ANDV cases and at 60% (63/105) among exposed close-household contacts, who remained uninfected (p < 0.05). The protective genotype (CC) was absent in all 85 ANDV cases, in both cohorts, and was present at 11.4% of the exposed close-household contacts who remained uninfected. Logistic regression modeling for risk of infection had an OR of 6.2–12.6 (p < 0.05) in the presence of TT and well-known ANDV risk activities. Moreover, an OR of 7.3 was obtained when the TT condition was analyzed for two groups exposed to the same environmental risk. Host genetic background was found to have an important role in ANDV infection susceptibility, in the studied population.</jats:p>
Scopus© Citations 12 4

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