Eco-epidemiology of rodent-associated trombiculid mites and infection with Orientia spp. in Southern Chile

Abstract

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.

Climate influences scrub typhus occurrence in Vellore, Tamil Nadu, India: analysis of a 15-year dataset

“…Scrub typhus is caused by the obligate intracellular bacteria Orientia tsutsugamushi in the tsutsugamushi triangle 1 , 2 Orientia chuto in UAE 3 and Orientia chiloensis in chile 4 . The infection is transmitted to humans through the bite of larvae (chiggers) of trombiculid mites which act both as the vector and reservoir of the infection 5 and are common ecto-parasites of rodents 6 and shrews 7 .…”

>b<Ectoparasitofauna (Acari: Ixodida and Gamasida; Insecta:Siphonaptera) from terrestrial mammals>/b<: diversity, taxonomic aspects and associated zoonotic rickettsiales in Legado das Águas - Reserva Votorantim, in Tapiraí and Miracatu, São Paulo

“…The Neotropical genus Quadraseta presents a wide variety of species and is mainly associated with small terrestrial mammals (Jacinavicius et al, 2018a) and has been associated with the presence of Orientia bacteria in specimens collected from rodents in Chile (Silva De La Fuente et al, 2023). This research found two species belonging to this genus, Q. pazca and Q. brasiliensis parasitizing five different species of rodents.…”

“…First of all, I'd like to thank God for giving me the opportunity to continually evolve and for my family, who have been with me from the moment I started my journey on this planet, especially my father Sergio, my mother Inês, my brother Felipe and my grandparents Sergio and Szabó et al, 2000;Pinto et al, 2009;Mendes-de-Almeida et al, 2011;Heukelbach et al, 2012;Horta et al, 2014;Paz et al, 2015;Regolin et al, 2015;Schott et al, 2019;Paz et al, 2022; Gonçalves et al, 2023;Silva et al, 2023 Tribe Pulicini Billberg, 1820…”