Background Scrub typhus is an emerging vector-borne zoonosis, caused by Orientia spp. and transmitted by larvae of trombiculid mites, called chiggers. It mainly occurs within a region of the Asia-Pacific called the tsutsugamushi triangle, where rodents are known as the most relevant hosts for the trombiculid vector. However, the reservoir(s) and vector(s) of the scrub typhus outside Asia-Pacific are unknown. The disease has recently been discovered on and is considered endemic for Chiloé Island in southern Chile. The aim of the present work was to detect and determine the prevalence of chiggers on different rodent species captured in probable sites for the transmission of orientiae responsible for scrub typhus on Chiloé Island in southern Chile and to molecularly examine collected chiggers for the presence of Orientia DNA.

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.

Gastrointestinal parasites are well-documented in small mammals from north-central Chile, but little is known about endoparasites of rodents in southern Chile. A survey was conducted between January and February 2018 to evaluate gastrointestinal parasites and risk factors of wild rodents that live in rural areas in Northern Chiloé Island, Chile. A total of 174 fecal samples from rodents of six native and one introduced species were collected and examined using the Mini-FLOTAC method. Also, 41 individuals of four native wild rodent species were examined furtherly to determinate adult parasites from gastrointestinal tracts. The overall prevalence of endoparasites was 89.65% (156). Helminth egg types included: Rodentolepis spp., Capillariidae, Trichuris sp., Syphacia sp., oxyurid-type eggs, Strongyloides sp., Spirurid-type eggs, Strongilid-type eggs, Moniliformis sp., and an unidentified nematode egg and larvae. Protozoa comprised coccidia, amoeba, and unidentified cysts. From necropsies, adult parasites involved Syphacia sp. Trichuris sp., Protospirura sp. and Physaloptera sp. In Abrothrix olivacea, individuals with low-body-mass index exhibited reduced infection probability for Spirurid-type and Strongilid-type eggs. Some parasites in this study may affect human health. In rural settings where environmental conditions are changing, more research should be undertaken to understand parasitic infections in wildlife and implications for public health and conservation.

To analyze the spatial distribution and validate the minimum distance between camera sites, we applied L-function (Besag's transformation of Ripley's K-function). This analysis identifies whether the spatial distribution of the camera sites follows a random, clustered or dispersed process, and identifies the average distance at which the respective process begins. In summary, the algorithm determines when the distribution process of camera sites passes from scattered to clustered considering a theoretical curve of a Poisson process. Given the special distribution of the 80 camera sites in this experimental design, the L-function yielded an average distance of 2,503.374 meters (Appendix Fig. S1.1). Below this distance, it is considered that the spatial process of camera site locations follows a random distribution.

Background: A series of abiotic and biotic modifications occur in an anthropogenic landscape which influence the ecology and physiology of wild hosts and their parasites. How these changes affect the parasitism is highly context-dependent, based on the host-parasite system and the type of perturbation. We aimed to investigate the differences in infestation with fleas and ticks of the native rodent Phyllotis darwini in three sites with different anthropogenic impacts and to evaluate environmental and host factors associated with parasite richness and load. Methods: We studied wild, rural and peri-urban sites of the semiarid region of Chile in the spring and summer seasons between 2018 and 2020. We applied a multi-level analysis to assess environmental and host variables at the individual and microhabitat level. We used Generalized Linear Mixed Models and Generalized Linear Models to test factor effects on the richness and load of ectoparasites of adult rodents.Results: Overall, out of 310 rodents trapped, 71% were flea-infested and 22% showed tick infestation. We identified six flea genera, being Hectopsylla sp. and Neotyphloceras sp. the most abundant fleas across sites. Flea richness was significantly higher in male rodents and during the spring and was positively affected by the micromammal species richness. The flea load was also higher in spring, in males, and positively associated to tick load. Hectopsylla sp., one of the most abundant fleas, showed a higher load in the peri-urban site and at grids with lower vegetation index values (NDVI), and Neotyphloceras sp. fleas were associated with tick load and lower temperatures. All ticks were larvae or nymphs of Ixodes sp. and showed a higher load in summer months and higher temperatures. Conclusions: We discuss possible environmental requirements of fleas and ticks, the association between their loads and male-biased parasitism. Further experimental investigations are needed to seasonally precise microclimate thresholds required for the survival of these ectoparasites.