Powassan Virus: Rare but Serious in the Northeast

Most Mainers who pull a tick off an ankle in June are thinking about one thing: Lyme. That makes sense. The deer tick that spreads Lyme is everywhere here, and Lyme is by far the most common thing it carries. But that same tick can carry something much rarer and much faster, a virus that kills roughly one in ten people who get severely ill from it.

What Powassan virus is, and why a rare disease still matters

Powassan is a tick-borne virus. The CDC describes it as uncommon but says cases are increasing, mostly in the Northeast and Great Lakes regions, from late spring through mid-fall when ticks are most active. We are squarely inside that window now.

The reason a rare illness earns a headline comes down to two things. First, speed. The Maine CDC says Powassan can spread from a tick to a person in as little as 15 minutes after a bite. Yale School of Public Health makes the same point, noting that Lyme usually takes hours to pass from tick to human while Powassan can move in a quarter of an hour. The slow tick check you do at the end of a hike helps a lot with Lyme. It buys you far less time against this virus.

Second, there is no treatment. The CDC is blunt about it: no vaccines or medicines exist to prevent or treat Powassan. Care is supportive, which means rest and fluids for mild cases and, in severe ones, a hospital.

The symptoms, and the part that should get your attention

The incubation period runs from about one week to one month, per the CDC, so a fever in July could trace back to a bite you barely noticed in June. Many people never feel sick at all. When the virus does turn serious, it can inflame the brain (encephalitis) or the membranes around the brain and spinal cord (meningitis), with confusion, loss of coordination, trouble speaking, and seizures.

Here are the numbers worth knowing. About 1 in 10 people with severe Powassan illness die. Of those who survive a severe case, roughly half are left with long-term problems such as recurring headaches, lost muscle strength, or memory trouble. Rare does not mean mild.

What the Maine and New England picture looks like

In April 2023, the University of Maine Cooperative Extension Tick Lab added Powassan to its testing panel. That matters because it gives the state a clearer count of what is actually out in the woods. In the lab’s 2024 surveillance season, it processed 4,776 tick submissions from 398 towns across all 16 Maine counties. Of the 3,650 deer ticks analyzed, 1.1 percent carried Powassan. For comparison, 41.5 percent carried the Lyme bacterium. So the virus is uncommon in the tick population, but it is present in every corner of the state.

The human toll is small and steady. The Maine CDC has counted 25 infections since 2014, including four deaths over the last decade. 2023 set a record with seven cases. 2024 brought three, in Kennebec, Lincoln, and York counties, including a death in York County. Nationally, preliminary CDC data recorded 54 Powassan cases in 2024 across 10 states, all of them neuroinvasive, with Minnesota reporting the most.

A Yale-led study published in the Proceedings of the National Academy of Sciences adds a useful wrinkle. Looking at 279 virus samples from deer ticks in Connecticut, New York, and Maine, researchers found Powassan clusters in small, scattered local hotspots rather than spreading evenly. Two Connecticut sites just 12.5 miles apart showed almost no mixing of the virus. In plain terms, your risk can be very local.

What you can actually do

The same habits that fend off Lyme are still your best defense, with the 15-minute clock in mind. Stick to trail centers and mowed paths. Use an EPA-registered repellent. Do a tick check the moment you come inside, not later that night. The blacklegged deer tick carries this virus, the same species behind Lyme and anaplasmosis across New England, so the routine covers several threats at once.

If you do get bitten, you can send the tick to the UMaine lab to learn what it was carrying. Our guide to tick testing at UMaine and UNH walks through how that works. And for the wider regional picture on tick season, prevention, and what to watch for, start with our complete Maine and New Hampshire tick and Lyme guide.

Sources

• U.S. Centers for Disease Control and Prevention. About Powassan Virus. CDC. 2024. https://www.cdc.gov/powassan/about/index.html
• U.S. Centers for Disease Control and Prevention. Signs and Symptoms of Powassan Virus Disease. CDC. 2024. https://www.cdc.gov/powassan/signs-symptoms/index.html
• U.S. Centers for Disease Control and Prevention. Historic Data (2004-2025), Powassan Virus. CDC. 2025. https://www.cdc.gov/powassan/data-maps/historic-data.html
• Maine Department of Health and Human Services / Maine CDC. Maine CDC Reports Death from Powassan Virus. Maine.gov. 2024. https://www.maine.gov/dhhs/node/5871
• University of Maine Cooperative Extension. UMaine Extension Tick Lab adds Powassan virus and Heartland virus to tick testing service. UMaine. 2023. https://umaine.edu/news/blog/2023/04/17/umaine-extension-tick-lab-adds-powassan-virus-and-heartland-virus-to-tick-testing-service/
• University of Maine Cooperative Extension. 2024 Surveillance Report from UMaine Extension Tick Lab highlights tick-borne disease risk. UMaine. 2025. https://extension.umaine.edu/2025/04/17/2024-surveillance-report-tick-lab-highlights/
• Yale School of Public Health. Tick-borne Powassan virus is being transmitted in concentrated clusters in New England, Yale study says. Yale School of Public Health (study in PNAS). 2023. https://ysph.yale.edu/news-article/tick-borne-powassan-virus-is-being-transmitted-in-concentrated-clusters-in-new-england-yale-study-says/

This article is for informational purposes only and does not constitute medical advice. Consult a qualified healthcare provider before making any health decisions.