4 West Nile virus cases so far this summer in Lancaster County

• By Lucy Albright/LNP | LancasterOnline

Lancaster County has had four human cases of the mosquito-borne West Nile virus so far in 2025, with those individuals likely infected in July and August, according to the state Department of Environmental Protection.

While the exact dates of infection aren’t available, the state Department of Health indicated the time frame in which they likely occurred. The state DEP logs cases of the virus and includes the data in its report this week.

The Lancaster County cases account for four of the 19 human cases that have been reported in Pennsylvania this year, according to the report. In 2024, Lancaster County had five reported human cases and two deaths, and in 2023 it had zero, according to state DEP data.

Primarily an illness of birds, West Nile virus was first found in Pennsylvania in 2000, according to the Pennsylvania Game Commission. The virus is typically transmitted by infected mosquitos. Unlike some other illnesses, it doesn’t commonly spread between people — coughing, sneezing and touch do not transmit West Nile virus, according to the federal Centers for Disease Control and Prevention. West Nile cases usually peak in late August to early September, according to the CDC.

Prevention tips

Since there are no licensed vaccines or medications available for West Nile, the CDC says the best way to stay safe is to avoid getting bitten. Wearing loose-fitting, long sleeved shirts and pants, using EPA-registered bug spray with ingredients like DEET, picaridin or oil of lemon eucalyptus and treating clothes and gear with permethrin can help protect you, as can taking steps to control mosquitos, the CDC says.

On its website, the state DEP encourages residents to remove standing water, which can turn discarded tires, bird baths, containers and even bottle caps into breeding grounds for mosquitos.

Health risks

Most people who catch West Nile virus will experience no symptoms, while about 20% will feel like they have the flu. Less than 1% will experience a more serious version of the disease affecting the central nervous system, according to the CDC. This can cause inflammation of the brain and of the membranes around the brain and spinal cord. About 10% of those who experience this severe form of the illness will die, and permanent symptoms are possible for those who survive.

Age increases the risk of severe illness from West Nile virus. Adults 65 and older are three times as likely to develop neurologic illness compared with those under 65, according to the CDC. Conditions like cancer, diabetes, high blood pressure and kidney disease also put people at higher risk of severe illness, as do weakened immune systems, the CDC says.