Study links animal die-offs to climate extremes

Davis, Calif.

- A research collaboration among three universities discovered that climate extremes often are to blame for mass die-offs in livestock and wildlife.

Diseases which often can be tolerated one at a time, like canine distemper virus (CDV), seem to transform into outbreaks when they follow climate conditions like flood and droughts, according to a team of scientists from the University of California-Davis, the University of Illinois and the University of Minnesota.

Researchers released their study in the June edition of Public Library of Science ONE, an online, peer-reviewed research journal. The project focused on the study of an unusually high mortality rate of lions in Tanzania's Serengeti National Park.

The study followed CDV outbreaks in 1994 and 2001, both of which were preceded by extreme droughts that caused the lions' main prey, Cape buffalo, to suffer heavy tick infestations.

With existing CDV presence suppressing the lions' immunity, the tick-borne diseases were capable of reaching fatal levels, the study notes.

"This study disclosed a key relationship between climate extremes and wildlife die-offs that had previously been unexplained," says Linda Munson, DVM, PhD, a UC-Davis professor of veterinary pathology and principal investigator in the study. "As climate extremes become more frequent, wildlife may be less able to cope with infectious agents that were formerly tolerated."

The study can be found here and was supported by the Morris Animal Foundation, the University of Illinois Research Board, the National Science Foundation Grants for Ecology of Infectious Diseases, Long-Term Research in Environmental Biology and Biocomplexity and the Messerli Foundation of Switzerland.