Mosquitoes in Manorville tested positive for a potentially deadly virus, the New York state Department of Health told Suffolk County health officials.

A mosquito sample tested positive for a eastern equine encephalitis, and New York state has declared an imminent threat to public health.

Suffolk County will now spray about 4,000 acres in Manorville and Calverton Friday night. Spraying was scheduled to begin at 7 p.m.

Suffolk County Health Commissioner Dr. James Tomarken says it's rare for people to contract the virus because the mosquito that carries it doesn't bite humans. He says another type of mosquito would have to bite an infected animal, like a bird, and then bite a human.

The mosquito sample was collected on July 31 in the Manorville area, according to the county.

Health officials say people who are infected will have the usual viral symptoms -- fever, muscles aches and joint pain -- and most will recover completely. They say small numbers are potentially at risk for more serious complications.