Comparative community-level associations of helminth infections and microparasite shedding in wild long-tailed macaques in Bali, Indonesia.

Helminthes have the capacity to modulate host immunity, leading to positive interactions with coinfecting microparasites. This phenomenon has been primarily studied during coinfections with a narrow range of geo-helminthes and intracellular microparasites in human populations or under laboratory conditions. Far less is known regarding differences in coinfection dynamics between helminth types, the range of microparasites that might be affected or the overall community-level effects of helminth infections on microparasites in wild systems. Here, we analysed the presence/absence and abundance patterns of enteric parasites in long-tailed macaques (Macaca fascicularis) on the island of Bali, Indonesia, to assess whether naturally occurring helminth infections were associated with increased shedding of the most common intracellular (Cryptosporidium spp., Isospora spp.) and extracellular (Entamoeba spp., Giardia spp.) microparasites. We also comparatively assessed the statistical correlations of different helminth taxa with microparasite shedding to determine if there were consistent relationships between the specific helminth taxa and microparasites. Helminth infections were associated with increased shedding of both intracellular and extracellular microparasites. Platyhelminthes repeatedly displayed strong positive correlations with several microparasites; while nematodes did not. Our results indicate that helminthes can influence microparasite community shedding dynamics under wild conditions, but that trends may be driven by a narrow range of helminthes.