Evaluation of species identification and rabies virus characterization among bat rabies cases in the United States.

To evaluate species identification and rabies virus (RABV) characterization among samples from bats submitted for rabies testing in the United States and assess whether a standardized approach to specimen selection for RABV characterization could enhance detection of a sentinel event in virus dissemination among bats. United States public health rabies surveillance system data collected in January 2010 through December 2015. The number of rabies-tested bats for which species was reported and the number of RABV-positive samples for which virus characterization would likely provide information regarding introduction of novel RABV variants and translocation and host-shift events were calculated. These specimens were designated as specimens of epizootiological importance (SEIs). Additionally, the estimated test load that public health laboratories could expect if all SEIs underwent RABV characterization was determined. Species was reported for 74,928 of 160,017 (47%) bats submitted for rabies testing. Identified SEIs were grouped in 3 subcategories, namely nonindigenous bats; bats in southern border states, Florida, Puerto Rico, and the US Virgin Islands; and bats of species that are not commonly found to be inflected with RABV. Annually, 692 (95% CI, 600 to 784) SEIs were identified, of which only 295 (95% CI, 148 to 442) underwent virus characterization. Virus characterization of all SEIs would be expected to increase public health laboratories' overall test load by 397 (95% CI, 287 to 506) samples each year. Species identification and RABV characterization may aid detection of a sentinel event in bat RABV dissemination. With additional resources, RABV characterization of all SEIs as a standardized approach to testing could contribute to knowledge of circulating bat RABV variants.