Manchester raises risk level for mosquito-borne illness to moderate

·2 min read

Aug. 31—Two batches of mosquitoes collected this month in Manchester have tested positive for West Nile Virus, prompting health officials to raise the risk level for mosquito-borne illness to moderate in the Queen City.

These are the second and third batches to test positive in the city this year, Phil Alexakos, chief operating officer of the Manchester Health Department, said Wednesday in a news release. The first detection was on July 20.

"We want to remind all of the residents of Manchester and neighboring communities to continue to take steps to prevent being bitten by mosquitoes and to eliminate standing water on their property," said city Health Director Anna Thomas in a statement. "A personal protective measure, like using an effective mosquito repellent, is the single most effective way to minimize risk."

If additional positive mosquito batches are detected, demonstrating sustained disease transmission and raising the local risk level to 'high risk,' public health officials said spraying operations to combat adult mosquitoes may get underway.

The Manchester Health Department maintains an annual Special Permit (SP-068) with the state Department of Agriculture's Division of Pesticide Control, allowing for expedited spraying by licensed pest control professionals, under such conditions.

First identified in New Hampshire in 2000, West Nile Virus is one of three "arboviruses" transmitted by mosquitoes here. The others are Eastern Equine Encephalitis (EEE) and Jamestown Canyon virus (JCV).

Symptoms of West Nile infection usually appear within a week after a bite, causing flu-like illness including fever, muscle aches, headaches and fatigue.

Many people develop no symptoms or very mild symptoms, but a very small percentage of those infected can go on to develop more serious central nervous system disease, including meningitis or encephalitis, according to the state Department of Health and Human Services.

Prevention guidelines for West Nile Virus and other arboviruses include the following:

1. Eliminate standing water and other mosquito breeding locations. In warm weather, mosquitoes can breed in any puddle that lasts more than four days.

2. Be aware of where mosquitoes live and breed and keep them from entering your home. Mosquitoes can enter homes through unscreened windows or doors, or broken screens.

3. Protect yourself from mosquito bites. If outside during evening, nighttime, and dawn hours when mosquitoes are most active and likely to bite, children and adults should wear protective clothing such as long pants, long-sleeved shirts, and socks.

4. Consider the use of an effective insect repellent, such as one containing DEET.

Anyone with questions about arboviruses, including WNV, can call the New Hampshire Bureau of Infectious Disease Control at 603-271-4496. Fact Sheets on West Nile virus and other arboviruses are available on the DHHS website.

For more information, visit the Centers for Disease Control and Prevention website at