Symptoms of a dangerous virus spread by ticks: Record number of cases in the US

Health authorities in the United States are issuing warnings about a significant surge in Powassan virus cases, a dangerous tick-borne illness capable of causing severe neurological conditions. The virus, first identified in 1958, reached a record number of reported cases in the U.S. during 2025, according to Unilad.

Named after the town of Powassan in Ontario, Canada, where it was first identified, the virus gained attention after a young boy contracted a then-unexplained illness. In recent years, the number of infections has risen sharply. In 2025, Powassan virus was diagnosed in 76 individuals in the U.S., a stark contrast to the average of about seven cases annually in previous years. The virus is transmitted through the bite of infected ticks, with three species identified as carriers: the groundhog tick, the squirrel tick, and the blacklegged or deer tick.

The virus is most prevalent in the Great Lakes region, Canada, and the northeastern United States. Dr. Jorge Parada, a medical advisor for the National Pest Management Association, highlighted the rapid transmission rate, noting that Powassan virus can be transmitted just 15 minutes after an infected tick bites a person, significantly faster than Lyme disease, which typically requires 36 to 48 hours of attachment.

Symptoms can be delayed, appearing up to four weeks after exposure. Initial signs may include fever, headache, vomiting, and weakness. As the illness progresses, more severe symptoms like confusion, loss of coordination, difficulty speaking, and seizures can occur. In critical cases, the virus can lead to encephalitis (brain inflammation) or meningitis (inflammation of the brain's lining), which can be life-threatening. Approximately 10% of individuals who develop severe neurological illness from Powassan virus die, and many survivors face long-term neurological deficits.

Currently, there is no specific cure for the Powassan virus. The CDC recommends rest, adequate fluid intake, and over-the-counter pain relievers to manage symptoms. Patients with severe forms of the disease may require hospitalization, including respiratory support, intravenous fluids, and medication to reduce brain swelling.

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The Powassan virus can be transmitted as little as 15 minutes after an infected tick bites a person, while transmission of Lyme disease usually requires the tick to be attached between 36 and 48 hours.