13 new West Nile cases confirmed in Nassau

Thirteen new cases of West Nile infection were confirmed in Nassau County Thursday and yet another in Suffolk, raising the number of people affected so far by virus-laden mosquitoes and raising new concerns about the impact the disease will have on the region this year.

Health officials in both counties expressed worry Thursday about the threat mosquitoes have posed this season - and could pose through fall. The insects remain in flight through October and Long Islanders will not see a reprieve, experts say, until at least two frosts force mosquitoes into dormancy.

Conditions of the most recently infected range from critical to fully recovered.

"This is the worst year we've had since West Nile was first found in our area," in 1999, Lawrence Eisenstein, deputy commissioner of Nassau's health department, said yesterday. Usually human infections start in August, he said, but a bumper crop of mosquitoes got a jump on the season and began infecting people in July. Experts cite weather conditions that have been conducive to mosquito reproduction.

A previous report that there were 15 new infections in Nassau was inaccurate. Two infections have already been reported this summer, bringing the total number of cases to 15.

Suffolk had just four West Nile cases so far but has seen the highest number of positive mosquito samples - 148 - compared with 71 in Nassau. Nine new positive pools from Suffolk were announced Thursday.

Epidemiologists say it's the growing number of positive mosquito samples that lies at the crux of the public health concern because the higher the number of positive pools, the more virus-carrying mosquitoes will have taken to the air. More than half the 60 known species of mosquitoes in the region can transmit West Nile.

Experts say the 219 positive pools found on Long Island so far this year represent the highest number reported in West Nile's 11-year history here.

"We are finding record numbers of West Nile virus mosquito samples in Suffolk County this year and are cautiously concerned about the threat to humans," Suffolk Health Commissioner James Tomarken said.

Last week, the state health department declared an emergency public health threat for Suffolk in the wake of the record number of positive samples. A declaration was issued for Nassau last month.

Still, public health experts urged residents not to panic and to take precautions against mosquito bites: wear long sleeves and pants from dusk until dawn when outdoors; keep screens on open windows and eliminate mosquito breeding habitats, such as standing water.

West Nile is an animal pathogen harbored by birds and transmitted to humans by female mosquitoes that have fed on fowl. The females need blood to produce fertile eggs. Most people - around 80 percent - bitten by West Nile-positive mosquitoes are unharmed. Those infected tend to be 50 and older or with suppressed immunity.

With Yamiche Alcindor