Effects of Waning Maternal Immunity on Infection Dynamics in Seasonally Breeding Wildlife

Increasing outbreaks of emerging infectious diseases originating from wildlife have intensified interests in understanding their dynamics in reservoir hosts. The effect of waning maternally derived antibodies on epidemics in a seasonally breeding wild mammal population is unclear. We examined how the population structure, influenced by seasonal breeding and maternally derived immunity, affects viral invasion and persistence using a hypothetical system based on Hendra virus infection in black flying foxes (Pteropus alecto). A deterministic Hendra virus epidemic model with uncertainty in parameter values was used to simulate transient epidemics following viral introduction into an infection-free population, including various timings within a year and differences in pre-existing seroprevalence. Additionally, we applied different modelling methods of waning maternal immunity to examine whether different models notably affected modelling outputs. The waning of maternally derived immunity temporally dispersed the supply of susceptible individuals in seasonally breeding populations, diminishing the effect of birth pulses generating the temporally synchronised supply of susceptible newborns. Thus, even in a population with seasonal births, a considerable level of probabilities of viral invasion and persistence could occur no matter when infectious individuals were introduced into the population. Viral invasion and persistence were substantially influenced by the modelling method of maternally derived immunity, emphasising the need to select an appropriate method and further investigate the waning pattern of maternally derived antibodies.