LA-CROSSE VIREMIAS IN WHITE-TAILED DEER AND CHIPMUNKS EXPOSED BY INJECTION OR MOSQUITO BITE

To further understand the role of wild mammals in the maintenance of L a Crosse virus (LACV) in nature, we investigated the effects of inocul ation method and virus source on the duration and amplitude of LACV vi remia in vertebrate hosts, Earlier work suggested that deer are not su fficiently susceptible to LACV to play an important role in its mainte nance. We re-evaluated the susceptibility of deer since subsequent stu dies showed that they constitute 65% of Aedes triseriatus blood meals, and thus would be exposed frequently to the virus. In our study, deer developed higher and longer viremias following exposure to LACV by in fected Ae. triseriatus than those previously reported by inoculation w ith needle and syringe. However, susceptible Ae, triseriatus that fed on these viremic animals did not become infected. Because a large numb er of uninfected mosquitoes can feed upon a viremic deer in nature, we believe that deer should not be disregarded completely as a possible amplifier in the LACV transmission cycle. We also infected chipmunks t o determine if there were significant differences in viremia response from mosquito delivery of virus to the chipmunk host, compared with ar tificial exposure by injection. Chipmunks exposed to infected mosquito es had higher and longer viremias than the ones produced by intramuscu lar injection of an LACV suspension. These findings show the importanc e of using LACV infected mosquitoes for transmission experiments in ma mmals.