Red fox and tick-borne encephalitis (TBE) in humans: can predators influence public health?

Analysing datasets from hunting statistics and human cases of tick-borne encephalitis (TBE), we found a positive correlation between the number of human TBE cases and the number of red fox (Vulpes vulpes). Time lags were also present, indicating that high numbers of red fox in 1 y translated into high numbers of human TBE cases the following y. Results for smaller predators were mixed and inconsistent. Hares and grouse showed negative correlations with human TBE cases, suggesting that they might function as dilution hosts. Combining our findings with food web dynamics, we hypothesize a diversity of possible interactions between predators and human disease - some predators suppressing a given disease, others enhancing its spread, and still others having no effect at all. Larger-sized predators that suppress red fox numbers and activity (i.e. wolf, Canis lupus; European lynx, Lynx lynx) were once abundant in our study area but have been reduced or extirpated from most parts of it by humans. We ask what would happen to red foxes and TBE rates in humans if these larger predators were restored to their former abundances.