EEE is a very rare but serious illness. It is a viral disease contracted through the bite of an infected mosquito. In most years, the virus is limited to native bird populations and bird-biting mosquitoes, but occasionally the virus can be transmitted to humans and domestic animals. EEE virus affects the brain with symptoms that appear 5 to 15 days after being bitten by an infected mosquito. Symptoms may include high fever, headache, stiff neck and decreased consciousness. The disease is often fatal in 30-50% of cases. Individuals with symptoms suggestive of EEE should contact their physician immediately.

   WNV is also a mosquito transmitted viral disease that causes encephalitis. However, mortality rates are much lower than those of EEE. It made its first appearance in the Western hemisphere, in the New York City area in 1999.

West Nile Virus (WNV) is a mosquito-transmitted disease that can cause encephalitis. It is common in parts of Africa, western Asia, and the Middle East. It appeared in the New York City region in the summer and fall of 1999, where some 59 human cases (including 7 deaths) occurred. This was the first incidence of this disease reported in the western hemisphere. Recent evidence suggests that the virus will establish in North America. Whether West Nile Virus will appear again in the summer of 2002 remains unknown.

The Disease

People can only contract WNV if bitten by an infected mosquito. Most people bitten by WNV-infected mosquitoes do not get sick. However, the elderly and people with weakened immune systems are more prone to infections. Symptoms begin 3-15 days after the bite from an infected mosquito. Symptoms may include fever, headache, nausea, rash, stiff neck, muscle weakness, and disorientation. WNV is fatal in some 3-15% of cases with serious symptoms. There is no vaccine for WNV

WNV Transmission Cycle

The natural cycle of WNV involves birds and mosquitoes. Mosquitoes acquire the virus from biting an infected bird. The mosquitoes are then able to transmit the infection to healthy birds, horses, and humans. Some bird species display no symptoms while other species may get sick and die, notably crows. Not all sick or dead birds will have the disease and there is no evidence that people can contract WNV directly from either live or dead birds. As is the case with all dead wildlife, do not handle dead birds with your bare hands.

Mosquito Species Involved

Several species of mosquitoes can transmit WNV from birds to humans. The urban "house mosquito" readily bites both birds and humans. This species is suspected to be most responsible for the 1999 outbreak in New York City. Other common species that can transmit WNV include one found throughout wooded areas in Rhode Island and two that are found in saltmarshes.

Seasonality of WNV

Humans can only contract WNV from the bite of an infected mosquito. If WNV appears in the northeast, it will be during the May to October period, when mosquitoes are active. Birds migrating northward in the spring are the likely source of introductionof the virus in the northeast. Also, indications are that WNV can survive in mosquitoes that overwinter in our area.

State Responses

State agencies in the northeast are preparing for the possible arrival of WNV in the summer of 2000. Several programs are intended to reduce the impact of WNV could have. These include:

1)increased support for communities' mosquito control programs

2)increased surveillance for infected mosquitoes and infected birds

3)a public awareness campaign

Community Responses

The risk of people acquiring WNV will be reduced by communities' efforts to reduce mosquito populations. The best approach is to target larvae (the immature aquatic stage) before they become adults. This strategy is preferred because larvae are a concentrated target and environmentally friendly products are available.

Appropriate habitats for larval control include stormwater catchment basins, roadside ditches, and retention ponds. Tire piles and other large sources of stagnant water should be eliminated. Coastal communities should address saltmarsh mosquito production.

Effective larval control programs conducted throughout the season will reduce the possibility of WNV appearing later in the season. If WNV is detected, then adult mosquito control will need to be considered. Killing adult mosquitoes is difficult because adults are widely dispersed. Also, pesticides used to kill adult mosquitoes have negative environmental impacts.

What You Can Do

Mosquito populations can be reduced on your property by eliminating the water that collects in containers such as buckets, tires, boats, unused swimming pools, and clogged rain gutters. For example, one tire can produce thousands of mosquitoes each year. Eliminating those sources reduces mosquitoes for the entire neighborhood. You can also assist by alerting community officials to mosquito production sites.

Personal Precautions

Some common sense measures that reduce your exposure to mosquitoes and mosquito-borne diseases, such as WNV, include:

1)limiting outdoor exposure

2)wear protective clothing

3)repairing window screens

4)using bug spray/repellents containing DEET - follow directions

Repellents containing "DEET" are very effective for most people. Products containing DEET in excess of 30% are unnecessary and increase the possibility of adverse reactions. Repellents containing DEET should not be used on infants and used with caution on children. These measures should be practiced every year during mosquito season.