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Stay alert: West Nile virus found in Manchester mosquitoes

MANCHESTER, NH —As school athletics escalate and many families spend more time outdoors enjoying hiking trails and other activities, the city’s health department issued a notice Wednesday saying that West Nile virus had been detected in a batch of mosquitoes collected in Manchester on August 15 and again on August 22.

“These are the second and third detections in Manchester this summer,” according to the memo.

In accordance with the NH1 Department of Health and Human Services’ Arboviral Disease Surveillance, Prevention and Response Plan, the local risk level has been raised to “moderate”.

Anna Thomas, MPH, director of public health for Manchester, said residents should continue to protect themselves when taking part in planned outdoor activities.

“We want to remind all residents of Manchester and surrounding communities to continue to take steps to avoid being bitten by mosquitoes and to remove standing water on their property. A personal protective measure, such as the use of effective mosquito repellent, is the most effective way to minimize risk.

This link to repellents rated by the EPA is deemed most effective against mosquitoes.

Avon Skin So Soft Bug Guard Plus is a popular repellent on the EPA list.

From the note:

Every summer/autumn since 2000 the City of Manchester Health Department collects and sorts mosquitoes which are then tested by the NH Public Health Laboratory for WNV, Eastern Equine Encephalitis (EEE) and Canyon Virus of Jamestown (JCV). This information is useful in determining the risk of disease to humans. If additional pools of positive mosquitoes are detected, demonstrating sustained disease transmission (“high risk”), public health interventions such as spraying of adult mosquitoes may be indicated according to national and local plans. The Manchester Department of Health maintains an annual Special Permit (SP-068) with the Pesticide Control Division of the NH Department of Agriculture, to allow expedited spraying by licensed pest control professionals, in such case.

WNV is one of three arboviruses transmitted by the bite of infected mosquitoes in New Hampshire. The other viruses are Eastern Equine Encephalitis (EEE) and Jamestown Canyon Virus (JCV). WNV was first identified in New Hampshire in August 2000. Symptoms usually appear within a week of being bitten and can include flu-like illness, including fever, muscle pain, headache headache and fatigue. Many people may develop no symptoms or only develop very mild symptoms. A very small percentage of people infected with WNV may develop more serious central nervous system disease, including meningitis or encephalitis. If you or someone you know has flu-like symptoms, including fever and headache, contact your local doctor.

Prevention guidelines for WNV and other arboviruses are available here:

Anyone with questions about arboviruses, including WNV, can call the New Hampshire Bureau of Infectious Disease Control at 603-271-4496.

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

Guidelines for the Prevention of West Nile Virus and Eastern Equine Encephalitis

1. Eliminate standing water and other mosquito breeding grounds.

In hot weather, mosquitoes can breed in any puddle that lasts longer than 4 days!

· Remove old tires from your property.

· Discard cans, plastic containers, ceramic pots or other containers. Do not neglect containers overgrown with aquatic vegetation.

· Drill holes in the bottom of recycling containers left outside.

· Make sure gutters are clean and well drained.

· Clean and chlorinate swimming pools and spas. If not in use, keep empty and covered and keep lids free of standing water.

· Aerate garden ponds or fill them with fish.

· Turn wheelbarrows and change water in birdbaths at least twice a week.

· Turn plastic wading pools upside down when not in use.

· Remind or assist neighbors to eliminate breeding sites on their properties.

Manchester residents can report “artificial mosquito breeding areas”: tires without rims, unmaintained swimming pools and other artificial areas of standing water to the Manchester Department of Health for investigation – (603) 624-6466 and ask Bifurquer environmental health service.

2. Know where mosquitoes live and breed and keep them out of your home.

· Mosquitoes lay their eggs in standing water. Weeds, tall grass, and bushes provide an outdoor home for adult mosquitoes, including several species commonly associated with West Nile virus and Eastern Equine Encephalitis.

· Mosquitoes can enter homes through unscreened windows or doors or broken screens. Make sure doors and windows have tight-fitting screens. Repair or replace any screens in your home that have tears or holes.

· Resting mosquitoes can often be chased away from indoor roosting sites by using sweeping motions under beds, behind bedside tables, etc. and once in flight, exterminated before sleeping at night.

3. Protect yourself from mosquito bites.

· If outdoors in the evening, at night and at dawn, 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.

· Consider using an effective insect repellent, such as one containing DEET. A repellent containing 30% or less DEET (N,N-diethyl-methyl-meta-toluamide) for children and adults. Use DEET according to the manufacturer’s instructions. Children should not apply DEET to themselves. Repellents containing picaridin, paramenthane-diol, or oil of lemon eucalyptus have also been shown to be effective.

· Vitamin B, ultrasound devices, incense and insect killers have not been shown to be effective in preventing mosquito bites.