Overview
- U.S. diagnoses climbed to 76 in 2025, the highest annual total on record and well above the historical average of seven to eight cases per year.
- Researchers and public-health experts report Powassan can pass from an infected tick to a person in as little as 15 minutes, a much faster timeline than Lyme disease.
- Infection can start with fever, headache, vomiting and weakness and can progress to encephalitis or meningitis with about 10% mortality among severe neurological cases and frequent long-term neurologic problems for survivors.
- There are no specific antivirals or vaccines for Powassan; clinical care is supportive, so officials urge repellents, treated clothing, protective dress and careful avoidance of tick habitats, especially in the Northeast and Great Lakes regions.
- Limited surveillance and diagnostic challenges complicate tracking, and experts note a broader rise in tick-related harms such as alpha-gal meat allergy, which CDC-linked research estimates has affected roughly 450,000 Americans.