Rabies, host population structure, and cross-species transmission to the migratory bat Tadarida brasiliensis in Chile

Although many bat species migrate, the consequences of migration for bat population structure and rabies virus transmission remain poorly understood. Understanding the spatiotemporal dynamics of bat rabies (Lyssavirus rabies) transmission is important to prevent rabies spillovers to dead-end hosts, including humans. Here, focusing on the long-distance migratory Brazilian free-tailed bat (Tadarida brasiliensis) in South America, we identify the extent of host population and rabies virus structure across Chile. The analysis of 112 cytochrome b sequences from T. brasiliensis individuals and 144 rabies virus sequences submitted to the Chilean national rabies surveillance showed a lack of geographic clustering by municipality or region in Chile. This lack of clustering suggests that the migratory behavior of this species might be homogenizing the population structure of T. brasiliensis and its species-specific rabies virus (TbRV-SA). While most rabies virus sequences of T. brasiliensis (92%) corresponded to the TbRV-SA lineage, we also detected T. brasiliensis individuals infected by rabies viruses that are more strongly associated with other bats, including Lasiurus spp., Histiotus spp., and Myotis spp (8%). In contrast, no other bat species were infected by TbRV-SA, suggesting the potential for a predominant asymmetric cross-species transmission observed in Chile. These results suggest that rabies risk could vary according to migratory bat movement patterns and community composition, especially in areas where cross-species transmission may be facilitated. Our study highlights the need to anticipate the spillover risk to humans and domestic animals associated with the long-distance spread of rabies virus in T. brasiliensis, and calls attention to clarify the role of urban areas as potential hotspots for cross-species transmission.