Until 1960, dogs were the most important animal host of rabies in the United States. After the institution of mandatory rabies vaccinations for dogs, wildlife species became the most frequently infected animals with rabies.  In 2007, 93.4% of the reported cases of rabies were in wildlife. While raccoons continue to be the most frequently reported rabid wildlife species in the United States (36.6% of all animal cases in 2007), bats made up 27.2% of animal cases in 2007, followed by skunks (20.4%) and foxes (6.7%).

In the U.S., rabies in terrestrial mammals can be linked to distinct virus strains. Each strain is maintained primarily by intraspecies (within species) transmission although spillover infection of other species may occur. 

In Michigan, both bat and skunk strains of rabies circulate.  Rabies in bats occurs throughout the state, and the north-central skunk strain of rabies occurs in the counties of southeastern Michigan and the "thumb" area. 

Rabies is typically transmitted by the bite of an infected animal via saliva. Once the virus has entered the body, it spreads to the nerves of the spinal cord where the virus will incubate for a period of time ranging anywhere from 3-12 weeks, although longer incubation periods have been recorded. The animal typically does not show any symptoms during this time. The virus moves up the spinal cord to the brain and finally infects the salivary glands. Symptoms of rabies will be present after the virus has moved to the salivary glands.

Non-bite exposures from animals are very rarely implicated in cases of human rabies.  However there have been cases of human rabies reported due to such exposures.  Examples include recipients of tissues or organs from donors that died of rabies, or persons exposed to large amounts of aerosolized virus in caves inhabited by millions of bats.

This page is maintained by the Michigan Department of Natural Resources