Skip Maine state header navigation

Agencies | Online Services | Help

Skip All Navigation

L&W Home > Permits & Standards > Waste Discharge > Special Topics > West Nile Virus > Background on West Nile Virus

When waterbuckets need to be left outside for pets or livestock, change the water regularly to avoid stagnant water where mosquitoes can breed.West Nile Virus -- Background

The following is a brief introduction. For links to further information, see the Materials Page.

What is West Nile Virus?

West Nile Virus (WNV) was first detected in North America during the summer of 1999, when the virus caused an outbreak of illnesses in New York City. Over the next four years, the virus spread to almost all areas on this continent. The virus affects birds when they are bitten by infected mosquitoes. When birds become infected, other mosquitoes that feed off of them acquire the virus, resulting in an expanding cycle of WNV. When a large number of mosquitoes become infected in an area, certain infected mosquitoes that also bite people can spread infection to humans through their bites. Link to clinical information from the Deparment of Human Services (off-site). Link to information on DEET (off-site).

Although WNV can cause serious and even life-threatening illness in people, most infected persons have only a mild illness or have no symptoms at all. Mild cases of WNV infection may include low-grade fever, headache, and muscle pains and require no treatment. More severe illnesses may include seizures, paralysis, and meningitis. Elderly persons appear to be more likely to get severe illness from infection than do younger individuals. Most cases of WNV in humans occur during the late summer and early fall.

What parts of the State are affected by West Nile Virus? Is it spreading further?

The Maine Bureau of Health has developed a surveillance system to track the emergence of West Nile Virus in Maine, among birds, mosquitoes and people. By tracking the spread of the virus, prevention efforts can be better focused to help educate the public regarding how to protect themselves and their families against the disease. In addition, other state agencies, health professionals and non-governmental groups have worked together since 2000 to increase awareness and promote preventive measures. Link to avian (bird) testing results from the Department of Health and Human Services (off-site).

Not all mosquitoes carry WNV. For more information, go here.