Long Island's second official case of West Nile virus in a human was reported Friday by Suffolk County health officials -- that of a man over 55 in the Town of Islip who was hospitalized in August and who has since recovered.
The other confirmed case this year was that of a man older than 60 in the Town of Hempstead who was hospitalized in mid-August and was recovering, a county health department spokeswoman said in September.
More people could have contracted the virus, but if symptoms were mild and people didn't seek medical help -- or if they did and no lab tests were conducted, the county would not have known, said James Tomarken, Suffolk County health services commissioner.
"We know about the cases in which the patient sought treatment and we received laboratory confirmation of West Nile virus," he said Friday in a news release.
Last year four human West Nile cases and no deaths were reported in Suffolk, with eight cases and no deaths in Nassau, officials said.
In some cases, the virus causes serious neurological illnesses that can lead to permanent conditions or death.
Last year, 2,469 cases of human infection were reported in the United States, resulting in 119 deaths, according to the Centers for Disease Control and Prevention.
Some mosquito bites can transmit West Nile to humans, with mosquitoes picking up the virus by feeding on infected birds.