An epizootic of hemorrhagic disease in white-tailed deer in Missouri

As part of a white-tailed deer (Odocoileus virginianus) survival study in M issouri (USA) we were actively monitoring 97 radio-collared deer when 8 (8% ) died. This mortality, which occurred from 20 August to 23 September 1896, consisted of five adult females, two yearling females and one yearling mal e. Based on the seasonality; of this mortality and the isolation of epizoot ic hemorrhagic disease virus (EHDV) serotype 2 from one of these animals, w e believe that these losses resulted from an epizootic of hemorrhagic disea se. The remains of five unmarked deer that may have died from HD also were found on the study area during this same period. During the fall following this mortality, we tested serum from 96 deer taken by hunters in the immedi ate area. Fifteen (16%) were positive for EHDV or bluetongue virus (BTV) an tibodies as determined by agar gel immunodiffusion tests. Serum neutralizat ion test results indicated that previous infections were caused by EHDV vir us serotype 2. Based on these data, and assuming that there was no prior ex posure to EHDV serotype 2 in this population, the exposure rate for this ep izootic was 24% of which 8% died. We noted hoof interruptions in only two o f the 96 deer sampled. During this mortality event, the Missouri Department of Conservation received no reports of dead deer, and without the radio-mo nitored animals the event would have been undetected.