Updated: West Nile Infected Mosquitoes Found in Medford

A small pool of mosquitoes infected by the West Nile Virus have been found in Medford, according to a press release from the city's board of health.

"It was a very small pool of mosquitos, but it means it is time to remind the citizens to use prevention," Karen Rose, city's public health director said in an email.

Chances of acquiring mosquito borne diseases such as WNV or EEE are slim, but residents should be aware that these viruses can cause fever, meningitis or encephalitis, the press release said.

Officials would not say specifically where the positive test came from in Medford. Julia Hurley, state department of health spokeswoman, said it was policy not to release the specific location.

"It doesn’t really matter," Hurley said. "Mosquitoes travel, so the risk is the same for all residents."

Rose said the virus was found in a pool of 27 mosquitoes, but she did not know how many of them tested positive.

A total of 107 tested mosquitoes pools in Massachusetts have turned up the West Nile Virus this year, according to department of health data.

Some West Nile prevention tips include:

• Be aware that mosquitoes are active in damp shady areas, during cloudy humid days, at dusk, dawn and during the night. 
• To protect yourself from mosquitoes use mosquito repellent and wear protective clothing.  Use repellents containing DEET, Picaridin or Oil of Lemon Eucalyptus and follow the directions on the label.  Never use DEET on infants.  Oil of Lemon Eucalyptus should not be used on children under three.  Although uncomfortable during hot days, long-sleeve shirts and long pants can provide a layer of protection. 
• Cover up the arms and legs of children playing outdoors.  Baby carriages and playpens should be covered with mosquito netting.
• Fix any holes in screens and screen doors and replace worn weather stripping. 

The press release didn't say where or when the mosquitoes were found in Medford.

The following is the full press release from the board of health:

The Mass. Dept. of Public Health has notified the Medford Board of Health that West Nile Virus (WNV) has been isolated from mosquitoes in Medford.  Though Medford has a vigorous prevention program through the East Middlesex Mosquito Control Program, it is important that each citizen use prevention and caution, and this news should serve as a warning that mosquitoes pose a health threat between now and early October.  Although the chances of acquiring mosquito borne diseases such as WNV or EEE are remote, residents should be aware that these mosquito-borne viruses could cause fever, meningitis or encephalitis.  Early symptoms of these diseases include fever, headache, stiff neck and muscle weakness.

Mosquitoes acquire WNV or EEE after biting an infected bird.  Those mosquitoes can then transmit that virus to a person, horse or to another bird.  Culex mosquitoes that develop in water holding containers are the primary vectors of WNV, while the mosquitoes that transmit EEE usually originate in wetlands.

During risk periods of WNV or EEE, residents should take preventative actions to avoid mosquito bites.

• Be aware that mosquitoes are active in damp shady areas, during cloudy humid days, at dusk, dawn and during the night. 
• To protect yourself from mosquitoes use mosquito repellent and wear protective clothing.  Use repellents containing DEET, Picaridin or Oil of Lemon Eucalyptus and follow the directions on the label.  Never use DEET on infants.  Oil of Lemon Eucalyptus should not be used on children under three.  Although uncomfortable during hot days, long-sleeve shirts and long pants can provide a layer of protection. 
• Cover up the arms and legs of children playing outdoors.  Baby carriages and playpens should be covered with mosquito netting.
• Fix any holes in screens and screen doors and replace worn weather stripping. 

There are certain actions that residents should take related to WNV.

• To prevent a yard from becoming a source for Culex mosquitoes, homeowners should make a thorough inspection of their property and remove, empty, cover or treat any water-holding containers.  During the summer, mosquito larvae can complete their development in water within a week.
• Containers where mosquitoes commonly lay eggs include neglected swimming pools, water in loose fitting pool covers or tarps, unscreened rain barrels, rimless tires, and plastic toys.
• Tires should be disposed of properly or stored inside.
• Rubbish barrels, wheelbarrows and small boats should be covered or stored upside down.
• The water in wading pools and birdbaths should be changed weekly.
• Infrequently used pools should be covered or properly maintained.
• Rainwater collection barrels should be screened, emptied once a week or treated with products containing Bti.

For further information on WNV or EEE, log on to the Massachusetts Department of Public Health web site at www.mass.gov/dph/wnv or the US Centers for Disease Control and Prevention at www.cdc.gov/ncidod/dvbid   If residents have any questions about mosquitoes or how to control them, contact the East Middlesex Mosquito Control Project at 781-899-5730 or visit their website at www.town.sudbury.ma.us/services/health/emmcp