Host condition, seasonality and environmental factors explain parasite community differences between urban and rural foxes

Abstract

Wildlife parasite communities are important for an OneHealth approach. The external environment impacts host-associated communities directly and via the hosts. Hosts in poor body condition are more susceptible to infection and parasite mode of transmission will affect occurrence: rural environments with better availability of intermediate hosts favour trophic transmission, while urban environments, often with dense host populations, favour direct transmission. We here study helminth communities within their synanthropic red fox (Vulpes vulpes) hosts (155 intestinal samples) using DNA metabarcoding of multiple marker genes (18S rRNA, 28S rRNA, COI). Controlling for sampling bias by incorporating DNA quantity and quality into models, we analysed the effect of environmental (urbanisation, seasonality) and host-intrinsic (weight, age, sex) variables on helminth communities. Helminth diversity was increased in younger hosts, in foxes with lower body weight and in those found in winter and spring. Host intrinsic drivers had smaller effects on the composition of the community, which was impacted by urbanisation, dependent on parasite transmission mode: surprisingly, transmission in two-host lifecycles was more pronounced in urban Berlin than in rural Brandenburg. Our results disagree with the prevailing hypothesis that trophically transmitted helminths are less prevalent in urban areas than in rural areas. Environmental drivers, i.e. urbanisation, affected each helminth species in the community differently, and we cannot generalise from helminth traits to their occurrences in urbanised areas. Finding co-infestations with multiple helminths and high infection intensity associated with poor body condition, however, might be relevant for a OneHealth approach.