Mosquito-borne Diseases in Vermont
In Vermont, mosquitoes are mostly a nuisance, but a few of them can carry diseases that affect people and some animals. Two diseases of concern in our state are West Nile virus (WNV) and Eastern equine encephalitis (EEE). The viruses that causes these diseases are called arboviruses (arthropod borne viruses), because they are caused by viruses and transmitted by arthropods, in this case mosquitoes.
West Nile Virus
West Nile virus was first detected in Vermont in 2000 and activity peaked in 2002 when 5 horses, 125 dead birds and one person tested positive for the virus. This virus was first introduced into the United States in 1999. Since then, it has spread throughout the 48 contiguous states. In the past few years, WNV activity has been low in New England. The last horse case in Vermont was reported in 2005 and the last human case was in 2003. However, a small number of birds or mosquitoes have tested positive every year.
Eastern Equine Encephalitis
Eastern equine encephalitis is also caused by a virus. No human or animal cases have been reported in Vermont. However, cases in horses or people have been reported from all of the other New England states, New York and Quebec. In Vermont, there has been limited testing for EEE virus in mosquitoes, and so far none have tested positive. However, in the fall of 2010, blood from hunted deer and moose was tested for evidence of infection, and about 11% of these samples were positive. This is the first time that evidence of EEE virus has been detected in Vermont.
More information
- CDC Mosquito-borne Diseases
- USDA West Nile Virus - information on West Nile virus and animals, primarily horses and other livestock