Investigating the persistence of tick-borne pathogens via the R0 model

In the epidemiology of infectious diseases, the basic reproduction number,R0, has a number of important applications, mostnotably it can be used to predict whether a pathogen is likely to become established, or persist, in a given area. We used theR0 model to investigate the persistence of 3 tick-borne pathogens; Babesia microti, Anaplasma phagocytophilum and Borreliaburgdorferi sensu lato in an Apodemus sylvaticus-Ixodes ricinus system. The persistence of these pathogens was alsodetermined empirically by screening questing ticks and wood mice by PCR. All 3 pathogens behaved differently in responseto changes in the proportion of transmission hosts on which I. ricinus fed, the efficiency of transmission between the host andticks and the abundance of larval and nymphal ticks found on small mammals. Empirical data supported theoreticalpredictions of the R0 model. The transmission pathway employed and the duration of systemic infection were also identifiedas important factors responsible for establishment or persistence of tick-borne pathogens in a given tick-host system. Thecurrent study demonstrates how the R0 model can be put to practical use to investigate factors affecting tick-borne pathogenpersistence, which has important implications for animal and human health worldwide