Rare tick-borne virus turns deadly fast as US cases reach record high, experts warn

A rare and potentially fatal tick-borne illness currently spreading across the United States can be traced back to a 1958 case involving a young boy on a farm.

The disease, known as Powassan virus, was named for the Ontario town near where it was first discovered.

At the time of his death, Lincoln Byers, a 4-year-old living in Canada, had a condition that medical professionals could not explain, the Boston Globe reported.

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Years later, researchers discovered a tick harboring the same virus on a dead squirrel, finally providing an answer to the tragedy, but foreshadowing a growing public health challenge.

While once considered an obscure medical anomaly, Powassan virus cases have reached historic highs in the U.S., data show.

According to the Centers for Disease Control and Prevention, 76 Americans were diagnosed with the virus in 2025, the highest annual total on record. Previously, the U.S. averaged just seven to eight diagnoses each year.

The virus is primarily transmitted to humans through the bite of an infected woodchuck tick or deer tick. Like other tick-borne illnesses, Powassan is most prevalent from late spring through mid-fall, when tick populations peak and outdoor activity increases.

Public health experts warn that the virus's transmission speed makes it uniquely dangerous.

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"One of the most dangerous aspects is its rapid transmission," Dr. Jorge P. Parada, a medical advisor at the National Pest Management Association in Chicago, told Fox News Digital.

"Powassan can be transmitted in as little as 15 minutes after the infected tick bites, while Lyme disease usually requires a 36- to 48-hour attachment time for transmission."

Parada noted that while Powassan remains rare compared to Lyme disease, it poses clinical concern.

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Dr. Marc Siegel, senior medical analyst for Fox News, confirmed that the virus transmits significantly faster than Lyme disease. He noted that Powassan carries an incubation period of one to four weeks before symptoms manifest.

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Initial symptoms include fever, headache, vomiting and weakness, though some infected individuals remain asymptomatic, according to the CDC.

The virus can progress to severe neurological complications, including encephalitis (inflammation of the brain) and meningitis (inflammation of the spinal cord membranes).

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In severe cases, patients may experience confusion, loss of coordination, difficulty speaking and seizures, per the CDC.

Approximately 10% of Powassan cases involving severe neurological disease are fatal, and many survivors experience long-term neurological issues.

There are currently no specific medications or vaccines to treat or prevent Powassan virus; clinical care is limited to supportive therapy, such as intravenous fluids and respiratory support.

While anyone can develop severe illness, those at the highest risk include children, older adults and immunocompromised individuals, experts caution.