Dynamics of two pathogens in a single tick population.

A mathematical model for a two-pathogen, one-tick, one-host system is presented and explored. The model system is based on the dynamics of , , and . The goal of this model is to determine how long an invading pathogen, , persists within a tick population, , in which a resident pathogen, , is already established. The numerical simulations of the model demonstrate the parameter ranges that allow for coexistence of the two pathogens. Sensitivity analysis highlights the importance of vector-borne, tick-to-host, transmission rates on the invasion reproductive number and persistence of the pathogens over time. The model is then applied to a case study based on a reclaimed swampland field site in south-eastern Virginia using field and laboratory data. The results pinpoint the thresholds required for persistence of both pathogens in the local tick population. However, , is not predicted to persist beyond 3 years. Understanding the persistence and coexistence of tick-borne pathogens will allow public health officials increased insight into tick-borne disease dynamics.