West Nile threat renewed

Wet summer is spreading virus

Plymouth County's first confirmed case of West Nile virus was found in a dead bird in Whitman. Spread by moquitoes, the virus sickens 20 percent of people it strikes. (David L. Ryan/Globe Staff)

The Plymouth County Mosquito Control Project was applying larvicide in Brockton last week, expecting the annual threat of West Nile virus to surface in an urban area. Then the county's first infected bird of the summer was discovered dead in Whitman Town Park, and the strategy shifted.

The mosquito control group sprayed and applied larvicide to the town's extensive parklands and ponds. Whitman officials have shortened recreation programs and asked sports coaches to schedule games earlier in the day. Peak exposure to mosquitoes occurs at dawn and dusk.

"Lots of people don't take it seriously until the virus shows up," said project superintendent Anthony Texeira.

State officials last week also reported the discovery of a diseased crow in Dedham, along with reports of West Nile-positive mosquitoes in Raynham and Barnstable, suggesting that West Nile has been established for the season by intense rainfall that allows mosquitoes to proliferate.

"We are continuing to find the virus in new areas, said Dr. Al DeMaria, an epidemiologist with the Department of Public Health. "The warm, wet summer is continuing to support mosquito populations and allowing the virus to spread."

Dedham officials said they plan to continue to work closely with the Department of Public Health and other agencies to offset threats of West Nile.

"We are also working with the Department of Public Works in treating the catch basins and putting information about West Nile virus on our website, www.dedham-ma.gov," the town's health director, Catherine Cardinale, said in a statement.

The Norfolk County Mosquito Control Project began treating rain basins around the county in early June and is almost finished, said director John J. Smith. Workers have been laying mosquito traps in Dedham near where the infected bird was found. Should any test positive for the virus, a decision on how to proceed will be made, he said. "Don't forget, when a bird shows up, it could have been infected 20 miles away."

The culex mosquito, which carries the virus, hibernates as an adult insect, usually in basements and other structures, and can thrive anywhere, Smith said. "It can be a cup of water."

The early detection of West Nile is a concern, he said. "It's not a good sign, I can tell you that."

Although Plymouth County Mosquito Control sprayed Whitman's park last week, the town Board of Health has requested another effort this week. Officials say they don't know if the bird became infected in town, or just died there.

A mosquito trap on Essex Street was checked but did not test positive for the virus, said health inspector Eric Badger.

"I think we've gotten right on top of things," Badger said. "We want to nip it in the bud, get the information out there, and make sure people are using repellent if they are outside at dawn or dusk."

Larvicide and spraying are only part of the solution, both Badger and Texeira stressed. Residents can prevent mosquitoes from multiplying by draining standing water where eggs are laid.

"Empty all containers and buckets and even that kiddie pool," Texeira said. "It only takes three or four days and then those eggs are mosquitoes."

Anyone can become infected with West Nile, although those over 50 are at the highest risk.

However, Badger urged residents not to panic. "Less than 1 percent of those infected come down with serious illness and only 20 percent get sick at all," he said. "Eighty percent show no signs."

Symptoms include a fever, headache, body aches, nausea, vomiting, and sometimes swollen lymph glands or rash on the chest, stomach, and back. In the rarest cases, severe symptoms include high fever, headache, stiff neck, disorientation, coma, tremors and convulsions, muscle weakness, vision loss, numbness, and paralysis.

Since January, the state Department of Public Health received reports of 1,016 dead birds, according to its website. Of the 63 birds submitted for testing, 60 tested positive for the virus, as did 10 mosquito pools.

In 2007, 3,059 dead birds were reported to the state, with 43 testing positive for West Nile.

No mosquitoes, horses, or humans have tested positive for the eastern equine encephalitis virus in Massachusetts so far this year.

To avert illness, officials say to make sure screens on windows and doors fit tightly. Reschedule outdoor activities in early morning or evening hours, which are peak mosquito times, or be sure to wear repellent and protective clothing.

More information about West Nile Virus or reports of activity around the state can be found at www.mass.gov/dph or by calling 1-866-MASS-WNV (1-866-627-7968).