Efficiency of anthelmintic treatment and its effect on microparasite dynamics in wild Mastomys natalensis.

Co-infections between helminths and microparasites can modulate the host immune response and alter disease dynamics, with potential implications for public health. However, identifying causal relationships in natural populations is challenging due to the complexity of ecological interactions. Perturbation experiments, where a specific parasite is selectively reduced, offers a powerful framework to directly test such interactions under natural conditions. In this study, we investigated potential helminth-microparasite interactions in the multimammate mouse (Mastomys natalensis) in Tanzania by experimentally reducing helminth infections in both captive and wild populations. We first confirmed that two anthelmintic treatments, ivermectin and pyrantel pamoate, effectively reduced gastrointestinal nematode burdens in wild-caught individuals. We then assessed whether 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. These findings suggest that helminth-microparasite interactions in M. natalensis may be subtle, context-dependent, or require longer timescales to become apparent.