Several days of rain, coupled with warm weather, means mosquito larvae will be hatching at a rapid pace.
"I expect to see an explosion of mosquitoes in the next week or so," said Sarah MacGregor, president of Dragon Mosquito Control. "The timing of this rain is absolutely bad."
And when there are more mosquitoes, there is an increased threat they could be carrying the potentially deadly Eastern equine encephalitis and West Nile virus.
Mosquitoes have tested positive for West Nile in Nashua and Manchester, which is earlier than usual, MacGregor said. Her company provides mosquito control to many Southern New Hampshire towns, testing and spraying as needed from spring to fall.
Although no mosquitoes have tested positive for EEE, mid-August is traditionally when the first cases appear, she said.
"We continue to trap in all of our towns," MacGregor said. "It's the time of year when we expect to see EEE. Historically, it's about now when it happens."
While mosquitoes that transmit West Nile virus tend to thrive in hot, dry weather, those that carry EEE are more prevalent in warm, wet conditions.
Because of the heavy rainfall in the last few days, MacGregor said, people should make there is no standing water on their property. Mosquitoes love to breed in water and catch basins, she said.
On Friday, Dragon Control sprayed larvicide in catch basins in Derry, Londonderry and Salem to prevent the mosquito population from growing, MacGregor said.
With Old Home Day scheduled this weekend in Londonderry, the company is spraying throughout town to protect residents from mosquito bites, according to Town Manager Dave Caron.
"We continue to work with our mosquito control contractor to monitor the situation closely," he said.
Salem Health Officer Brian Lockard said the town contracts with MacGregor because officials don't want to take any chances with EEE or West Nile.
"You don't want to panic or anything, but you want to be aware of the issue," he said. "Knock on wood, but so far we haven't had any West Nile virus in EEE in Salem."
No mosquitoes have tested positive in Salem since 2005, he said. That's the same year 20-year-old Kelly Labell of Newton died after contracting EEE.
Dragon keeps a close watch on Newton and other Rockingham County towns where mosquitoes are especially prevalent. Those towns include Kingston, East Kingston and Brentwood, according to MacGregor.
Chris Adamski of the state Division of Public Health said despite the recent rain, it's too early to tell if this will be a prime year for mosquitoes.
"I think it's still a little premature to make any predictions," she said.
As of Aug. 13, 19 people and four animals in the state had been tested for West Nile or EEE, with no positive cases, Adamski said.
Of 881 batches of mosquitoes tested, there was the one positive result in Nashua and two in Manchester, she said.
Adamski recommends people make sure they wear clothing that can prevent mosquito bites, use repellent and be careful when outside at dawn or dusk.
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