Long-term studies of hantavirus reservoir populations in the southwestern United States: A synthesis

A series of intensive, longitudinal, mark-recapture studies of hantavirus i nfection dynamics in reservoir populations in the southwestern United State s indicates consistent patterns as well as important differences among site s and host-virus associations. All studies found a higher prevalence of inf ection in older (particularly male) mice; one study associated wounds with seropositivity. These findings are consistent with horizontal transmission and transmission through fighting between adult male rodents. Despite very low rodent densities at some sites, low-level hantavirus infection continue d, perhaps because of persistent infection in a few long-lived rodents or p eriodic reintroduction of virus from neighboring populations. Prevalence of hantavirus antibody showed seasonal and multiyear patterns that suggested a delayed density-dependent relationship between prevalence and population density. Clear differences in population dynamics and patterns of infection among sites, sampling periods, and host species underscore the importance of replication and continuity of long-term reservoir studies. Nevertheless, the measurable associations between environmental variables, reservoir pop ulation density, rates of virus transmission, and prevalence of infection i n host populations may improve our capacity to model processes influencing infection and predict increased risk for hantavirus transmission to humans.