Parasite prevalence in lemurs: Habitat disturbance and individual characteristics as explaining factors

Parasite prevalence and associated infectious diseases play an important role in ecological, social and evolutionary processes, but the potential drivers of parasitic loads are still unclear. However, habitat disturbance as well as individual characteristics have been shown to influence parasite prevalence in several animal species. This study aims to explore general mechanisms and determinants of gastrointestinal parasite infections in prosimian primates. Methods included the non-invasive sampling of faecal samples from three sympatric, congeneric lemur species (Eulemur rufifrons and E. rubriventer) that were screened for eggs and larvae of parasites. We found two species of parasites that are considered as genuine parasites of these Eulemur sp.: Callistaura sp. and Lemuricola sp.. The prevalence of Callistaura parasites was significantly higher in lemurs ranging in pristine areas compared to those who range in more disturbed areas. In addition, individual variation in age and sex turned out to be associated with parasite loads, as adults show a higher Callistaura prevalence compared to sub-adults. In terms of sex we find contrasting results, with males showing a higher prevalence of Lemuricola infections compared to females. In contrast, females are more heavily infected with Callistaura parasites than males, probably due to the different life cycles and transmission modes of these parasite species. The association between parasite prevalence and reduced host fitness, combined with the parasites' potential to spread infectious diseases among wildlife and human populations, underlines the importance of this project from an anthropological, ecological, and a conservation perspective.