Efficiency of anthelmintic treatment and its effect on microparasite dynamics in wild <em>Mastomys natalensis</em>

Abstract

Co-infections between helminths and microparasites can modulate the host immune response and alter diseasedynamics, with potential implications for public health. However, identifying causal relationships in naturalpopulations is challenging due to the complexity of ecological interactions. Perturbation experiments, where aspecific parasite is selectively reduced, offers a powerful framework to directly test such interactions undernatural conditions. In this study, we investigated potential helminth-microparasite interactions in the multi-mammate mouse (Mastomys natalensis) in Tanzania by experimentally reducing helminth infections in bothcaptive and wild populations. We first confirmed that two anthelmintic treatments, ivermectin and pyrantelpamoate, effectively reduced gastrointestinal nematode burdens in wild-caught individuals. We then assessedwhether helminth reduction influenced the prevalence of viral and bacterial infections in free-living populations.Our results revealed no significant short-term effect of anthelmintic treatment on microparasitic infections. Thesefindings suggest that helminth-microparasite interactions in M. natalensis may be subtle, context-dependent, orrequire longer timescales to become apparent