Pennsylvania site just recorded highest rate ever of tick-carried virus anywhere in U.S.

By Marcus Schneck | mschneck@pennlive.com
An infection rate higher than any previously recorded anywhere in the country for “the dangerous and rare” deer tick virus has been found in ticks in a Pennsylvania park.

The Pennsylvania Department of Environmental Protection reported Thursday that its Vector Management Program detected “an unusually high infection rate” deer tick virus – a type of Powassan virus – in samples of adult ticks recently gathered in Lawrence Township Recreational Park near Clearfield in Clearfield County.

Transmitted by blacklegged ticks, also called deer ticks, DTV is a type of Powassan virus, which is rare in the U.S. but has been increasing in recent years. It can be transferred from tick to human within 15 minutes of a tick bite and can result in encephalitis or meningitis and hospitalization, and death in about 12 percent of people with the severe form of the disease.

Other tick-borne diseases, such as Lyme disease, take much longer to cause infection, typically 24 hours or more after the tick attaches to the host.

“The infection rate of ticks sampled from the Lawrence Township Recreational Park is extremely high, deer tick virus transfers very quickly through the bite from an infected tick, and the health outcomes from the deer tick virus are more severe than other tickborne illnesses typically seen in Pennsylvania,” said DEP Secretary Patrick McDonnell.

In samples from the park, 92 percent – 23 out of 25 sampled ticks – were positive for DTV.

The previous highest rate found at a single location in Pennsylvania was 11 percent, and the highest reported nationally in scientific literature was approximately 25 percent.

The statewide average infection rate for DTV in Pennsylvania was 0.6 percent in 2021.

The DTV-positive ticks were discovered during routine testing as part of DEP’s active tick surveillance program, a five-year pilot program that began in 2018. Surveys are conducted in every county in Pennsylvania to track tick habitats, life stages and peak activity levels, and to test them for human pathogenic diseases.

Fall and winter surveillance focuses on analyzing adult blacklegged ticks for emerging and changing disease burdens in public use habitats across Pennsylvania, such as parks, playgrounds and recreational fields.