Mosquitos in East Boston for the first time this summer have tested positive for the West Nile Virus (WNV). Hyde Park, and South Boston where also added to the Boston Public Health Commission’s (BPHC) list of confirmed WNV positive pools that contain infected mosquitoes. Last month, WNV positive mosquitoes were found in West Roxbury, Dorchester, and Roslindale.
Of the 14 positive pools citywide, two mosquitoes were collected in East Boston, three in South Boston, six in Hyde Park, and three in Roslindale.
Last week, the Massachusetts Department of Health raised the risk level for WNV infection in Boston from low to moderate. Despite the increased positive mosquito pools, there have been no confirmed human cases of WNV in Boston this year.
“It’s that time of year when it’s not uncommon to find mosquitoes infected with the West Nile Virus in the Boston area,’’ said Dr. Anita Barry, director of the Infectious Disease Bureau at the BPHC.
While WNV is most commonly transmitted to humans by the bite of a mosquito infected with the virus, WNV poses very low risk to humans, Dr. Barry said. But even that low risk can be reduced if people take a few simple steps to protect themselves and their families.
She said those steps include using insect repellant when outdoors, especially from dusk to dawn when mosquitoes are more likely to be biting; wearing clothing with long sleeves and pants, when possible; mosquito-proofing your home by ensuring that window and door screens are in good repair to prevent mosquitoes from getting into the house; preventing mosquitoes from breeding in standing water by turning over unused flower pots, buckets, wheelbarrows, and garbage cans; removing leaves and other debris that can clog gutters and trap water; and disposing of or covering old tires; and covering swimming pools and kiddie pools when not in use.
The city is putting larvicide in catch basins in East Boston and other Boston neighborhoods to reduce the number of mosquitoes.
About one in 150 people infected with WNV will develop severe illness. The severe symptoms can include high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis. These symptoms may last several weeks, and neurological effects may be permanent.
Up to 20 percent of the people who become infected have symptoms such as fever, headache, and body aches, nausea, vomiting, and sometimes swollen lymph glands or a skin rash on the chest, stomach and back. Symptoms can last for as short as a few days, though even healthy people have become sick for several weeks.
Approximately 80 percent of people (about four out of five) who are infected with WNV will not show any symptoms at all.
People typically develop symptoms between three and 14 days after they are bitten by the infected mosquito.
There is no specific treatment for WNV infection. In cases with milder symptoms, people experience symptoms such as fever and aches that pass on their own, although even healthy people have become sick for several weeks. In more severe cases, people usually need to go to the hospital where they can receive supportive treatment including intravenous fluids, help with breathing and nursing care.
Milder WNV illness improves on its own, and people do not necessarily need to seek medical attention for this infection though they may choose to do so. If you develop symptoms of severe WNV illness, such as unusually severe headaches or confusion, seek medical attention immediately.
Severe WNV illness usually requires hospitalization. Pregnant women and nursing mothers are encouraged to talk to their doctor if they develop symptoms that could be WNV.
People over 50 at higher risk to get severe illness. People over the age of 50 are more likely to develop serious symptoms of WNV if they do get sick and should take special care to avoid mosquito bites.
Being outside means you’re at risk. The more time you’re outdoors, the more time you could be bitten by an infected mosquito. Pay attention to avoiding mosquito bites if you spend a lot of time outside, either working or playing.
Risk through medical procedures is very low. All donated blood is checked for WNV before being used. The risk of getting WNV through blood transfusions and organ transplants is very small, and should not prevent people who need surgery from having it. If you have concerns, talk to your doctor.
For more information on WNV, call the Boston Public Health Commission at 617-534-5611 or visit www.bphc.org.