Oct. 9--Heavy rains propagated a huge number of mosquitoes last week and then cooler weather knocked them back, but this year's risk of West Nile virus will not subside until the first hard freeze, insect and public health experts said.
Consequently, now is not the time to drop your guard against Connecticut mosquitoes. Cases of West Nile virus infection have been diagnosed in October.
"In previous years, we have had people become ill with WNV infection in October, so it is important that Connecticut residents take this threat seriously," said Dr. Robert J. Galvin, commissioner of the state Department of Public Health.
This year Connecticut has recorded seven cases of West Nile virus, but no fatalities. Last year there were 4 cases. WNV has claimed three lives and sickened 68 in Connecticut since 2000.
"West Nile Virus will continue to be a threat until the weather turns cold enough to end the mosquito season and taking the recommended personal protection measures to avoid mosquito bites as the most effective way to prevent mosquito-borne diseases such as West Nile virus," Galvin said.
Until last week, abundant rainwater gave rise to 4 to 5 times the usual number of mosquitoes, and last week about 19,000 mosquitoes were caught in traps. By the start of October the number had decreased to 8,640 per week, said Theodore Andreadis, chief medical entomologist at the Connecticut Agricultural Experiment Station, where mosquitoes are tested.
This year, mosquitoes testing positive for WNV were identified at 33 locations in 25 towns across the state.
People should still avoid mosquito bites, Andreadis and Galvin said.
Minimize time outdoors at dusk and dawn, use repellent containing DEET, and make sure screens are in good repair. Do not let water collect in outdoor containers such as pots, tires and wheelbarrows.
Meanwhile, the Connecticut Agricultural Experiment Station is conducting research into Eastern equine encephalitis, or EEE, a potentially fatal mosquito-borne virus that has not been found in Connecticut since 2004.
Genetic analysis of EEE virus by Experiment Station scientists suggests the sporadic virus spends Connecticut winters in avian hosts, Andreadis said. EEE also persists elsewhere, from upstate New York and New Hampshire, the study found.
Results were published in August in the American Journal of Tropical Medicine and Hygiene.
West Nile virus winters in mosquitoes tucked into basements and other structures that protect them from cold.
Consequently, WNV is very predictable in Connecticut and emerges every summer; EEE is extremely unpredictable, seeming to strike at random, Andreadis said.
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