Diversity and eco-epidemiology of ectoparasites and Rickettsia spp. associated with the opossums Didelphis albiventris Lund, 1840 in livestock farms from Argentinian Pampas region

Abstract

Many ectoparasites species serve as vectors for bacteria that are significant to both public and animal health, with wild, domestic and synanthropic mammals acting as reservoir. However, limited information exists on the circulation and incidence of these vectors in Argentina. We examined the diversity, prevalence, and abundance of ectoparasites, along with the presence of Rickettsia spp., of Didelphis albiventris within a rural landscape of the Pampas region, Argentina. We also analyzed ectoparasite variations in ectoparasite populations concerning seasonality, livestock farm type, and farmers’ management practices. Seven species of hematophagous ectoparasites were collected, including mites (Laelapidae: Laelaps echidninus); ticks (Ixodidae: Ixodes loricatus); fleas (Rhopalopsyllidae: Polygenis platensis and Polygenis rimatus, Stephanocircidae: Craneopsylla minerva wolffhuegeli, Pulicidae: Ctenocephalides felis); and lice (Polyplacidae: Polyplax spinulosa). Additionally, two bacteria were detected: Rickettsia felis and Ricketssia sp. closely related to R. belli. Fleas were the most prevalent and abundant group and C. felis showed the highest values in all the parameters analyzed. Parasitological comparisons between dairy farms and feedlots revealed similar results, with comparable densities of D. albiventris in both farm types. Ectoparasites abundance varied seasonally, peaking during the colder season. Regression analysis indicated higher ectoparasite infestation levels on farms with more dogs. The detection of pathogenic bacteria, coupled with the high prevalence and abundance of vectors, such as C. felis, suggests a significant epidemiological risk in the region. The commensal behavior of D. albiventris facilitates it to thrive in areas modified by anthropogenic activity, positioning this species as a potential nexus between wild and domestic epidemiological cycles of parasites and emerging pathogens. Therefore, our findings suggests that D. albiventris plays a key role in the transmission and maintenance of ectoparasites and ectoparasite-borne bacteria in within these ecosystems.