29 mosquito samples test positive for West Nile virus in Warren County, above annual average
WARREN COUNTY, N.J. — Twenty-nine mosquito samples have tested positive for West Nile virus in Warren County so far this year, more than double the county’s annual average of 11 positive samples.
The latest samples of mixed Culex mosquitoes were collected Sept. 1 from gravid traps in Belvidere, Franklin Township, Frelinghuysen Township, Greenwich Township, Lopatcong Township, Oxford and Washington Township. Two of the samples were collected in Franklin Township.
The 1999-2025 average for Warren County is 11 West Nile virus-positive mosquito samples per year, according to the Warren County Mosquito Control Commission.
Positive mosquito samples have been found this year in Belvidere, Franklin Township, Frelinghuysen Township, Greenwich Township, Hackettstown, Harmony Township, Hope Township, Knowlton Township, Liberty Township, Lopatcong Township, Mansfield Township, Oxford, Phillipsburg and Washington Township.
Lopatcong Township has recorded five positive samples, the most of any municipality listed, followed by Washington Township with four. Belvidere and Franklin Township have each recorded three.
For West Nile virus surveillance, adult mosquitoes are collected using traps designed to catch Culex mosquitoes, which are responsible for transmitting the virus, particularly from bird to bird. Each sample contains up to 75 adult mosquitoes of the same species collected from a single location.
The Warren County Mosquito Control Commission has collected and submitted mosquito samples for testing each week since the state laboratory began testing May 18.
Four people have been confirmed positive for West Nile virus in New Jersey this year, and there have been two presumptive viremic blood donors, according to the commission.
Mosquito populations are currently very high in portions of Warren County following recent rainfall. Commission staff conduct daily larval mosquito control throughout the county, while treatments targeting adult mosquito populations in areas with West Nile virus-positive samples are conducted as weather permits.
Residents are encouraged to eliminate standing water on their properties, use mosquito repellents containing DEET, picaridin or oil of lemon eucalyptus and avoid being outdoors when mosquitoes are most active, typically around dawn and dusk.
Neglected swimming pools can be reported to the Warren County Mosquito Control Commission at 908-453-3585 or through its website. Anonymous reports are accepted.
Symptoms of the mild form of West Nile virus can include fever, headache, tiredness, body aches and swollen lymph glands. Less than 1% of infected people, or about one in 150, develop severe illness.
Severe symptoms can include high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis. These symptoms may last several weeks, and neurological effects may be permanent. West Nile virus infection can be fatal.
