Gastrointestinal helminth infections and ectoparasitism in wild rodents along wildlife-human interfaces in Tanzania

Background: Gastrointestinal parasites pose a significant threat to human and domestic animal health across Africa. Despite numerous studies on ectoparasitism and endoparasitism in small mammals across different regions of the continent, the ecological role of rodents in transmission dynamics of gastrointestinal helminths remains poorly understood. This study aimed to identify gastrointestinal helminths in rodents and evaluate the influence of host-related factors, ectoparasite infestations, and environmental variables on helminth prevalence at wildlife-human interfaces in Tanzania. Methods: Gastrointestinal helminth eggs were quantified using the modified McMaster method on samples from captured rodents. Correlations between parasitological data, host scaled mass index (SMI), and ectoparasite intensity were analyzed. Generalized linear mixed models (GLMMs) were employed to assess helminth occurrence in relation to host demographics, ectoparasite load, and environmental factors. Results: The overall prevalence of gastrointestinal helminths was 53.59%. Seven distinct helminth egg types were identified, representing two major taxa: nematodes and cestodes. Among the nematodes, eggs of Trichuris spp., Strongyloides spp., Syphacia spp., Capillariidae and Spirurida were identified. Cestode eggs present were Hymenolepis-like eggs and eggs of Anoplocephalidae. Whipworms (Trichuris spp.) exhibited the highest prevalence (23.2%), followed by threadworms (Strongyloides spp.) at 22.1%. Anoplocephalid eggs showed the lowest prevalence, at 0.56%. The occurrence of gastrointestinal helminths in rodents was significantly associated with increased SMI and ectoparasite (flea and mite) infestations, while also varying across rodent species and collection sites. Conclusions: This study highlights the presence of potentially zoonotic helminths, including capillariids and Hymenolepis-like species, in rodents at wildlife-human interfaces. Furthermore, it identifies associations between gastrointestinal helminth infections and host body condition, as well as the intensity of ectoparasite infestations. These findings underscore the importance of considering host and environmental factors in understanding helminth transmission dynamics and their potential impact on public and veterinary health.