Ecological determinants of rabies virus dynamics in vampire bats and spillover to livestock

Abstract

The pathogen transmission dynamics in bat reservoirs underpin efforts to reduce risks to human health and enhance bat conservation, but are notoriously challenging to resolve. For vampire bat rabies, the geographical scale of enzootic cycles, whether environmental factors modulate baseline risk, and how within-host processes affect population-level dynamics remain unresolved. We studied patterns of rabies exposure using an 11-year, spatially replicated sero-survey of 3709 Peruvian vampire bats and co-occurring outbreaks in livestock. Seroprevalence was correlated among nearby sites but fluctuated asynchronously at larger distances. A generalized additive mixed model confirmed spatially compartmentalized transmission cycles, but no effects of bat demography or environmental context on seroprevalence. Among 427 recaptured bats, we observed long-term survival following rabies exposure and antibody waning, supporting hypotheses that immunological mechanisms influence viral maintenance. Finally, seroprevalence in bats was only weakly correlated with outbreaks in livestock, reinforcing the challenge of spillover prediction even with extensive data. Together our results suggest that rabies maintenance requires transmission among multiple, nearby bat colonies which may be facilitated by waning of protective immunity. However, the likelihood of incursions and dynamics of transmission within bat colonies appear largely independent of bat ecology. The implications of these results for spillover anticipation and controlling transmission at the source are discussed.

WITHDRAWN: Demographic and ecological drivers of infectome diversity in companion cats

“…To gain a better understanding of microbial dynamics among cat populations, it's important to move beyond descriptive host-pathogen associations and strive for a mechanistic understanding of when and where infectious pathogens are transmitted, as well as how the entire pathogen community (infectome) is influenced by the environment and local host communities (22,23). For instance, changes in parasite richness in wild animals have been linked to habitat loss and fragmentation, indicating that anthropogenic alterations in host species composition and population densities can directly impact parasite community compositions (24)(25)(26)(27)(28)(29). Similarly, anthropogenic land-use changes have been observed to influence virus community compositions, suggesting their role as a key determinant of host viromes (30)(31)(32)(33).…”

Effects of culling vampire bats on the spatial spread and spillover of rabies virus

“…4A; median/mean culled, 4.114/11.56 km/year (95% HPD, 0.01 to 47.86), versus non-culled, 5.16/13.8 (0.01 to 54.42)]. Reports of nearby rabies circulation during the previous 6 months also had a consistent (retained in 98.3% of trees) negative effect on viral dispersal speed, which may reflect the accumulation of immunity in bat populations from immunizing exposures or more intense culling in areas with recent spillover to livestock ( 29 ). We also observed a small positive effect of the time since the epizootic origin (“MRCA time”), indicating an acceleration of viral spread through time, and a separate effect signaling that heightened detection or reporting of cases (“sampling intensity”) improved detection of longer distance viral dispersals.…”

Quantifying Spillover Risk with an Integrated Bat-Rabies Dynamic Modeling Framework

“…To study this in more detail, the model would need to be modifed to include within roost dynamics. However, little is known about the immunological processes related to lyssavirus infection within D. rotundus; this knowledge gap includes seroconversion/ seroreversion rates and transmissibility [45]. Although modeling may provide insight into the incidence of infection at the roost level, the incidence and therefore prevalence within the roosts remains an uncertainty in our metapopulation model.…”