Monitoring wildlife parasites for One Health

Abstract

Understanding how ecosystems respond to stressors like climate change and human activities is key for One Health initiatives. Parasites play a critical role in maintaining ecosystem complexity, by increasing biodiversity (which can dilute the impact of parasites on individual hosts) and the number of interspecific interactions, and ultimately ecosystem robustness and resilience in face of global change. Anthropogenic changes may alter ecosystem health, potentially inducing shifts in host ranges (e.g. spillovers). Such human-induced shifts in host ranges need to be closely monitored and their mechanisms beter understood, as they could result in the emergence of new infectious diseases. We investigated the link between habitat degradation and shifts in parasite communities, using parasites as indicators of ecosystem health in Lake Victoria (Eastern Africa). We compared macroparasite communities of 13 cichlid fish species 20 years before and after the onset of anthropogenic perturbations, using historical and recent fish collections. We observed a decline in parasite abundance, biodiversity indices, co-infections and a change in host-parasite combinations, with switches to new host species. This highlights the need of a monitoring plan of wildlife parasites, to preserve their ecosystem services in face of global change. We also assessed the effect of two recent human disturbances – predator invasion and eutrophication – on parasite communities, by comparing parasite communities between lake ecosystems similar and close to Lake Victoria but differing in perturbation types. This space-for-time approach will reveal whether the observed changes in parasite communities in Lake Victoria reflect a natural state or are a result of recent human disturbances and, if so, which disturbance. The study confirms the interconnection between wildlife, ecosystem and humans, and shows the potential of the new “historical ecology of parasitism” sub-field in the context of One Health research, offering the opportunity for long-term monitoring of wildlife diseases. This could reveal early warning signs of infection outbreaks or emergence of new diseases and contribute to develop policy strategies.