Mosquito-Borne Virus Risk in NH

This week the New Hampshire Department of Health and Human Services (DHHS) announced the beginning of the statewide eastern equine encephalitis (EEE) and West Nile virus (WNV) surveillance season. The season will run from the first of June to the end of October.

The regions expected to be most at risk are the Rockingham County, Eastern Hillsborough County, Southern Merrimack County, and Southern Strafford County. These counties all had a public health threat declared in them during the 2006 season because of the increased risk to citizens in these areas.

Eastern equine encephalitis (EEE) is a mosquito-borne viral disease that occurs in the eastern half of the US where it has been seen in humans, horses, and some birds. If bitten by an infected mosquito, EEE symptoms usually develop within 3-10 days. The disease is incredibly dangerous with a mortality rate of approximately one-third of all infected patients. Patients are hospitalized and there exist only treatments but no cures or vaccines for the virus. It is one of the most serious mosquito-borne illnesses in the country.

West Nile virus (WNV) is another mosquito-borne viral disease that shows up across North America, generally flaring up in the summer and ending in the fall. About 80% of those infected with WNV will show no symptoms at all and only about one in 150 will develop severe illness. People over 50 are more likely to develop serious symptoms from the virus.

In 2007 there were no identified cases of WNV but there were 3 human cases of EEE, 6 mosquito pools with EEE, and 2 animals identified to have been infected with EEE.

"Due to high EEE and WNV activity in NH during recent years, there is a concern these diseases will again be a health concern in 2008," said DHHS Commissioner Nicholas Toumpas. "Yet, while EEE and West Nile remain threats to the public, these diseases are preventable so there is no reason to stop enjoying the outdoors. It is essential that people follow the prevention steps, such as using an insect repellent, to avoid becoming infected by one of these viruses."

Besides the previously approved repellents, those containing DEET, picaridin, or oil of lemon eucalyptus, a new type, IR3535, has been approved by the U.S. Centers for Disease Control and Prevention (CDC) as safe and effective in reducing mosquito bites. Insect repellents and reducing standing water around your house are the best defense, according to the CDC.

In New Hampshire, there are actually 47 different species of mosquitos. Only a few of them are important in carrying and spreading EEE and WNV.

More information about EEE and WNV can be found at
http://www.dhhs.state.nh.us/DHHS/CDCS/LIBRARY/Fact+Sheet/mosquito-contro...