Nassau's health department first discovered an infected mosquito pool June 30 in Bethpage. That is the earliest discovery of the virus since data collection began in 1999, spokeswoman Mary Ellen Laurain said. In Suffolk the first positive sample this year was June 23 in West Babylon, the earliest reporting since the county began collecting data, also in 1999, said the health department's Scott Campbell.
Friday, Nassau reported six new mosquito samples had tested positive. They were collected in Valley Stream, the Massapequa Preserve (two pools), Merrick, Wantagh and in Westbury earlier this month. Laurain said the county did not want to make any predictions on the season based on the positive samples. She said the county would continue to monitor 42 sites and intensify monitoring at sites where positive samples were recorded.
Suffolk officials announced seven new positive samples Friday at Heckscher State Park in East Islip, Belmont Lake State Park in North Babylon (two pools), West Babylon, Deer Park, North Lindenhurst and in Holtsville. The lack of rain and high temperatures may have intensified the cycle of the virus spreading between birds and mosquitoes as they congregate at limited water sources, Campbell said.
"You're going to have it ping-ponging," he explained. Cooler temperatures, however, could slow that cycle.
West Nile virus, first detected in New York in 1999, is an infection spread by mosquitoes that can cause serious illness and death. Since 2000, there have been more than 254 human cases of West Nile in the state, including 26 deaths. This year, New York has found 52 mosquito pools that tested positive for the virus, but no human cases.
Bryon Backenson, a research scientist for the state Health Department, said this is the time when positive tests start to increase and numbers would likely rise through September.
But even when cases have popped up as early as May, he said, it was not necessarily an indicator of a bad season. "West Nile virus is always a little difficult to predict," he said.
New York has about 30 species of mosquitoes infected with West Nile, but only a dozen species are capable of transmitting it. "What we saw in April or May with a particular species that comes out in that particular time may be a little different from what we are seeing now, which may be a little different from what we may be seeing in September."
According to the Centers for Disease Control, 23 states have reported West Nile activity as of this week, with 10 human cases reported in eight states. Spokeswoman Kristen Nordlund said while transmission rates seem to be going down overall, a slight increase in case numbers has been noted in the West and Midwest.