West Nile Virus Found in Multiple Suffolk Communities, Including Southold

Suffolk County health officials confirmed this week that mosquitoes testing positive for West Nile virus have been found in at least 10 locations throughout the county, among them Southold, as the summer mosquito season reaches a more active phase.

The Suffolk County Department of Health Services announced Tuesday that 10 mosquito samples had come back positive for the virus. In addition to Southold, infected samples were collected in Riverhead, Bay Shore, Lindenhurst, West Islip, Northport, Port Jefferson Station and Mastic Beach. Officials noted that 22 mosquito samples in total had tested positive for the disease so far this season.

The virus turned up this year for the first time at the William Floyd Estate in Mastic Beach, which lies within the Fire Island National Seashore. Park staff said mosquitoes were collected July 25 from a trap maintained under a collaborative monitoring program between the National Park Service and the county's Arthropod-Borne Disease Laboratory. West Nile virus had previously been detected on national seashore lands in August 2025 and annually since 2023, officials said.

Given the heightened risk, the Suffolk County Department of Public Works has planned ground-spraying operations at Davis Park on Fire Island on Thursday, running from 5:30 in the evening until 9 p.m. The treatment will cover all streets and boardwalks in the community using the ultra-low volume aerosol pesticide sumithrin, also marketed as Anvil.

Health officials urged residents to use insect repellents containing DEET, picaridin, IR3535 or oil of lemon eucalyptus, and to wear long sleeves and pants when outdoors. Residents were also advised to use air conditioning and intact window screens, and to eliminate standing water around their homes to reduce mosquito breeding.

Those seeking details about the spraying schedule may reach the Suffolk County Division of Vector Control at 631-852-4270 or the Spraying Information Hotline at 631-852-4939.