Clinical rabies is caused by a virus from the genus Lyssavirus. Within the Lyssavirus genus, a number of other viruses have been identified that infect mammalian hosts (animal and human) causing fatal encephalitis. Rabies virus is the Lyssavirus associated with rabies in bats and terrestrial mammals around the world. The other Lyssaviruses have been identified in bats in Europe, Africa, Asia, and Australia.
Rabies is transmitted from animal to animal through transfer of virus-contaminated saliva by bites or mucous-membrane exposures. In the United States, rabies virus subtypes have become associated with the mammalian species in which the subtype is generally found. In Indiana, the North Central Skunk virus and numerous bat subtypes of rabies virus have been identified.
Since 1990, bats have been the predominate species diagnosed with rabies at the Indiana State Department of Health (ISDH) Laboratory (the only Indiana lab that does rabies testing). Bats continued that trend in 2004, as most of the animals that tested positive were bats. The horse diagnosed with rabies in 2002 was infected with a bat strain of the rabies virus. Figure 1 shows animal rabies cases by species in Indiana for 2000-2004.
In 2004, 4 percent of bats submitted to the ISDH Laboratory were determined to be rabid.