In addition to Fontaine, who was being treated at Children's Hospital in Boston, a 52-year-old woman from Lakeville and a 23-year-old man from Acushnet have contracted the virus this year. In the last four years, a total of four people in the state have been killed by the virus, which can cause inflammation of the brain and lead to a coma and death.

Feman makes sure he shuts the door to the house now, and is more careful when he lets the dogs in and out. But, the contractor said, "we have mosquitoes in the house still. Where the hell do they come from?"

Since an aerial spraying by the state on Aug. 9, the first in 16 years, no new cases of the virus have been detected in mosquitos caught in traps in the town, Healey said. "It's an indicator that what was here is no longer here," the town manager said.

Additional aerial spraying over southeastern Massachusetts was begun Aug. 22. Together, the two rounds of spraying appear to have largely eliminated the area's mosquito population, with some officials estimating that more than 80 percent of mosquitoes were eradicated.

The state Department of Public Health is expected to know the results of last week's spraying within a few days. The agency will then decide if another round of aerial spraying is needed, said Ed Kiely, chief of staff for the department.

Kiely cautioned residents to remain vigilant and use repellent, despite the progress in the mosquito wars. "There's no way to kill 100 percent of the mosquitos, and aerial spraying is not a silver bullet," Kiely said. "It reduces risk; it doesn't eliminate it."

Fran Cass, a maintenance worker for Middleborough, said he believes townspeople recognize the mosquito problem as a potentially long-term threat.

"Everybody knows there's a reasonable risk," he said, standing near the playing field where Fontaine collapsed.

For his part, Cass said, he wears pants and long-sleeve shirts whenever possible. In addition, Cass endorses another idea that he believes could help reduce mosquitoes.

"Bat houses," he said. "They're a natural predator. Bats are the way to go."