State Health Officials Announce Decline in Mosquito Population Following Most Recent Aerial Spraying

BOSTON — The Massachusetts Department of Public Health (DPH) today announced that aerial spraying, which took place in six southeastern Massachusetts communities on August 13, cut the mosquito population in half in the spray area. Aerial spraying generally kills only those mosquitoes that are in flight during the spray operation, and health officials continue to stress the importance of personal protective measures to prevent mosquito bites.

"Today’s results reduce but do not eliminate the public health threat of mosquito-borne illnesses in Massachusetts," said DPH Commissioner John Auerbach. "It remains vitally important that people continue to take precautions to protect themselves and their families from mosquito bites — use insect repellant, cover exposed skin, and avoid outdoor activities at dusk and after nightfall when mosquitoes are at their most active."

Officials conducted aerial spraying on August 13 in Bridgewater, Easton, Norton, Raynham, Taunton, and West Bridgewater following the detection of multiple mosquitoes infected with Eastern Equine Encephalitis (EEE) in the area.

There has been one confirmed human case of EEE in a Massachusetts resident this year, a Metrowest resident who may have contracted the disease while traveling out of state. There were two cases of EEE in August of last year acquired in Massachusetts; a fatal case in a Bristol County man and an infection in a tourist from out of state. EEE activity in both 2010 and 2011 raised public concern and prompted DPH to work with a panel of experts to evaluate and enhance the state’s surveillance and response program. EEE is spread to humans through the bite of an infected mosquito. EEE is a serious disease in all ages and can even cause death.

People have an important role to play in protecting themselves and their loved ones from illnesses caused by mosquitoes:

Avoid Mosquito Bites

• Apply Insect Repellent when Outdoors. Use a repellent with DEET (N, N-diethyl-m-toluamide), permethrin, picaridin (KBR 3023), oil of lemon eucalyptus [p-methane 3, 8-diol (PMD)] or IR3535 according to the instructions on the product label. DEET products should not be used on infants under two months of age and should be used in concentrations of 30% or less on older children. Oil of lemon eucalyptus should not be used on children under three years of age.
• Be Aware of Peak Mosquito Hours. The hours from dusk to dawn are peak biting times for many mosquitoes. Consider rescheduling outdoor activities that occur during evening or early morning.
• Clothing Can Help Reduce Mosquito Bites. Wearing long-sleeves, long pants and socks when outdoors will help keep mosquitoes away from your skin.

Mosquito-Proof Your Home

• Drain Standing Water. Mosquitoes lay their eggs in standing water. Limit the number of places around your home for mosquitoes to breed by either draining or discarding items that hold water. Check rain gutters and drains. Empty any unused flowerpots and wading pools, and change water in birdbaths frequently.
• Install or Repair Screens. Keep mosquitoes outside by having tightly-fitting screens on all of your windows and doors.

Protect Your Animals

Animal owners should reduce potential mosquito breeding sites on their property by eliminating standing water from containers such as buckets, tires, and wading pools — especially after heavy rains. Water troughs provide excellent mosquito breeding habitats and should be flushed out at least once a week during the summer months to reduce mosquitoes near paddock areas. Horse owners should keep horses in indoor stalls at night to reduce their risk of exposure to mosquitoes. If an animal is diagnosed with WNV or EEE, owners are required to report to DAR, Division of Animal Health by calling 617-626-1795 and to the Department of Public Health (DPH) by calling 617-983-6800.

More information, including all WNV and EEE positive results from 2012, can be found on the Arbovirus Surveillance Information web page at www.mass.gov/dph/wnv or by calling the DPH Epidemiology Program at 617-983-6800. The findings of the DPH Eastern Equine Encephalitis Expert Panel can be found here:

• Report of the EEE Expert Panel 

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