A second mosquito has tested positive in Suffolk County for West Nile virus, the Suffolk health department announced Saturday.

The mosquito sample, known as a Culex Pipiens-resuans, was found June 23 in Selden, according to an email sent out by the health department. The first mosquito sample to test positive for West Nile was found June 18 in South Huntington and reported June 26 to the department.

No humans, horses or birds have tested positive for West Nile in Suffolk County this year. The virus has existed in the county since 1999, when it was first tested in birds and mosquitoes. It can be transmitted to humans through mosquito bites. Dead birds are a strong indicator of the virus.

StoryOfficials: 1st sample tests positive for West Nile in '15OpinionOpinion: Mosquito solution we're ignoring

"While there is no cause for alarm, we urge residents to cooperate with us in our efforts to reduce the exposure to the virus, which can be debilitating to humans," Suffolk County Health Services Commissioner James L. Tomarken said in a written statement.

There were no reported positive samples in Nassau as of late last month.

West Nile symptoms can include high fever, headache, neck stiffness, muscle weakness, vision loss, numbness and comas. Effects from the virus can last several weeks or permanently. It mostly affects people 50 or older.

advertisement | advertise on newsday

Last month, the New York City health department says, the virus was detected in mosquitoes in Glen Oaks in Queens and New Dorp Beach on Staten Island.

Residents are urged to avoid mosquitoes around their home by eliminating stagnant water where mosquitoes breed and to avoid activities at dusk and dawn, wear long-sleeved shirts and pants when outdoors for long periods of time, use bug spray, and add screens to all windows and doors.

Dead birds or West Nile-related activity can be reported to Suffolk County at 631-787-2200 from 9 a.m. to 4 p.m. Monday through Friday.

Medical questions can be answered at 631-854-0333 or at Suffolkcountyny.gov/health