Trends in national surveillance data for bat rabies in the United States: 2001-2009.

Rabies remains an important public health concern in the United States, with most human cases associated with bat rabies virus variants. Cases of rabies virus (RV) infection in bats are widely distributed across the continental United States and elsewhere in the Americas. In this retrospective study, data on bats submitted to state laboratories for RV diagnosis between 2001 and 2009 were analyzed to investigate epidemiological trends in the United States. Season, region, and roosting habits were the primary risk factors of interest. During the study interval, more than 205,439 bats were submitted for RV diagnosis, and 6.7% of these bats were rabid. Increased odds of a submitted bat being rabid were associated with species that exhibit inconspicuous roosting habits, bats originating in the Southwest, and bats submitted for diagnosis during the fall. Periodic analysis of zoonotic disease surveillance is recommended to detect changes in trends regarding geographic distribution, seasonal fluctuations, and host associations; this is particularly necessary, as existing trends may be influenced by climate change or other emerging factors.