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

• Published in: PLOS Neglected Tropical Diseases
• Main Authors: Silva de la Fuente, Maria Carolina, Perez, Caricia, Martinez-Valdebenito, Constanza, Perez, Ruth, Vial, Cecilia, Stekolnikov, Alexandr, Abarca, Katia, Weitzel, Thomas, Acosta-Jamett, Gerardo
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2025
• Subjects: 03 Good Health and Well-being; 03 Salud y bienestar; Pacific; Antarc*; Antarctica; Mite
• Online Access: https://repositorio.uc.cl/handle/11534/92383; https://doi.org/10.1371/journal.pntd.0011051

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. Author summaryScrub typhus is an ...