Heterogeneity in contact rates leads to explosive amplification of white-nose syndrome in bats

Background/Question/Methods

Emerging infectious diseases can have devastating impacts on wildlife and threaten species with extinction. Heterogeneity in host social behavior that determines contact rates among individuals and the environment can have profound impacts on pathogen transmission and thus disease outcome. White-nose syndrome, caused by the fungal pathogen, Pseudogymnoascus destructans, has caused precipitous declines in bat populations across Eastern North America. However, impacts vary considerably among species and populations, and it has been suggested that social behavior may be contributing to the observed differences in impacts. We measured contact rates among bats and with the hibernacula environment by marking two species of bats (Myotis lucifugus and Perimyotis subflavus)at four winter hibernation sites in Wisconsin with a UV-fluorescent dust, and followed the spread of the dust through the community of bats and hibernacula environment during hibernation. 

Results/Conclusions

We found that social behavior varied significantly among species with a more socially gregarious species, Myotis lucifugus, making more bat-to-bat contacts than the solitary roosting Perimyotis subflavus. Contact rates were also highly skewed among individuals, with some bats making many contacts and others very few. This heterogeneity greatly amplifies pathogen transmission and is a partial explanation for the explosive emergence of this pathogen and severe impacts on bat populations.