Mosquito-borne viruses threaten city

Mandy Miller | 8/22/2012, 10:22 a.m.

As the extreme heat tapers down, adults and children alike face increased risk of mosquito-borne illnesses through late summer and early fall.

According to the Massachusetts Department of Public Health (MDPH), the highest risk for contracting mosquito-borne illnesses, such as West Nile Virus (West Nile) and Eastern Equine Encephalitis (EEE), occurs between July and September.

But the Centers for Disease Control and Prevention (CDCP) reported last week that West Nile is spreading faster than it has in years. As of August 14, the CDCP reported West Nile cases in 43 states and confirmed 26 deaths.

Mosquito pools testing positive for West Nile and EEE have been found in Massachusetts. While the Boston Public Health Commission (BPHC) doesn’t expect an outbreak of EEE within the city, it has reported 15 mosquito pools pulled from Roslindale, West Roxbury, East Boston, Hyde Park, North and South Dorchester, Jamaica Plain and Back Bay Fens areas that tested positive for West Nile.  

Carried and transmitted by mosquitoes, EEE and West Nile are not spread by infected humans or mammals but, in very rare cases, West Nile may be transmitted from mother to child through breastfeeding, blood transfusion or organ transplant.  

According to the National Center for Biotechnology Information, most of those bitten by West Nile-infected mosquitoes do not know they’ve been infected and few notice any symptoms, which include fever, headache, body aches, nausea and vomiting.

Most people infected with West Nile recover on their own, although the elderly and young are more susceptible to more serious illness.

EEE is a very rare disease that causes swelling of the brain. The CDCP says only a few cases of EEE are reported in the United States each year, with most occurring in the Atlantic and Gulf Coast states. Initial symptoms include fever, stiff neck, headache and lack of energy.  

“If you have been bitten and have those flu-like symptoms, you need to go to the emergency room,” said Dr. Barbara Ferrer, executive director of the BPHC. “They will evaluate and test you. If you don’t have severe symptoms but are concerned you may be infected, contact your doctor.”

Although there are no specific treatments or vaccines for the viruses, a healthcare provider may prescribe medications to relieve symptoms.

While the MDPH does take precautionary measures to prevent the spread of mosquito-borne illnesses every year, the best thing people can do is take protection into their own hands.

“As a city, Boston takes aggressive steps to control the mosquito populations by applying larvicides in catch basins, which prevents mosquitoes from hatching,” explained Ferrer. “Pesticide spraying from trucks may also occur if a need is determined.”

Mosquitoes can develop into adults in as little as one week and they can begin to multiply in any puddle or standing water that exists for more than four days.

The growth of the mosquito population can be cut down by eliminating areas of standing water. While the MDPH can remove standing water in public areas, it is important for residents to proactively eliminate standing water on their own property.