Health officials have confirmed three human cases of West Nile virus in New York City this season.
A 61-year-old Bronx man was the first city resident to contract the virus this season and was hospitalized, the health department says. That man also suffered from meningitis.
Two Staten Island women, a 74-year-old and a 46-year-old, also contracted the virus. Both were hospitalized.
Last month, a 66-year-old woman from Long Island was identified as the state's first confirmed case of West Nile virus this year. She became ill on July 5, and was recovering at home.
The state has since issued a public health advisory for Nassau County and cautioned area residents to watch out for mosquito bites. The county identified 18 new sites on Thursday where mosquitoes have tested positive for West Nile virus, according to Newsday.
West Nile virus is spread by mosquitoes that often pick up the virus from birds they bite. Symptoms include neck stiffness, disorientation, coma and paralysis.
"A warm, dry summer is triggering an increase in West Nile virus in the mosquito population earlier than expected," state health Commissioner Dr. Richard Daines said in a statement. "Nassau and Suffolk counties, as well as New York City, recently have detected West Nile virus in mosquitoes at much higher rates than they have seen in the past several years at this time of the summer."