Rare Tick-Borne Virus Powassan Is Spreading Fast in the US
A rare tick-borne illness called Powassan virus has been quietly climbing toward record numbers, and unlike Lyme disease, it can infect you in minutes.
Cases in New Jersey and New Hampshire have made national headlines this year because of how severe the symptoms can get.
How Fast This Actually Spreads
Powassan is carried by the same deer ticks responsible for Lyme disease, but the comparison stops there once a tick actually bites.
"Unlike with Lyme disease — where the tick generally needs to feed on your blood for 16 to 24 hours to transmit the disease — with Powassan, it seems like the tick does not have to be attached to you for much longer than 15 minutes or so," said Catherine Valentine, a clinical assistant professor in the division of infectious diseases at NYU Grossman School of Medicine, in comments to The Washington Post.
The longer an infected tick feeds, the more virus is transmitted, and the sicker a person may become, said Saravanan Thangamani, a professor of microbiology and immunology at SUNY Upstate Medical University.
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The Numbers Behind the Headlines
What's actually driving the recent attention isn't a single outbreak. It's a steady, multi-year climb that's now hit a new high.
CDC data shows just 7 reported Powassan cases in the United States in 2015. By 2025, that number had risen to 76, the most ever recorded in a single year.
Most cases occur in the Northeast and Upper Midwest, primarily transmitted by deer ticks, though groundhog and squirrel ticks can carry the virus too — they're simply less likely to bite people, since they live deep in wooded areas most people avoid.
What Happens If You're Infected
Most people who get infected likely never develop symptoms at all, according to Valentine. Those who do typically start with fever and flu-like symptoms — and for many, that's where it ends.
In others, the virus moves into the central nervous system within a few weeks, causing confusion, garbled speech, loss of coordination, or seizures. "It wouldn't be unreasonable for someone to think they're having a stroke," Valentine said, though one key difference is timing: stroke symptoms appear suddenly, while a brain infection develops over days.
Among people who develop symptoms, the fatality rate reaches as high as 15%, and half of survivors are left with lasting neurological effects, ranging from minor memory lapses to serious difficulty speaking, walking, or eating.
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Why There's No Real Treatment Yet
There is no approved treatment or vaccine for Powassan virus. Severe cases are managed with supportive care, including IV fluids and respiratory or feeding support when needed, with some doctors prescribing steroids to reduce brain inflammation.
Thangamani believes the rise in cases is being driven primarily by climate change. Warmer average temperatures have extended tick season considerably, with cases now showing up as early as March and as late as November in some regions. Milder winters have also allowed deer and rodent populations to grow, carrying ticks into new areas.
He suspects the disease remains under-recognized rather than over-diagnosed, since mild or flu-like cases can easily go unconnected to a tick bite the patient may not even remember.
How to Actually Protect Yourself
Avoiding a bite in the first place remains the only real defense, since there's no treatment once someone is infected.
Tuck pants into socks when hiking or spending time in wooded areas, wear clothing treated with permethrin, and use an EPA-registered tick repellent. After coming inside, run clothes through a hot dryer cycle for 10 minutes to kill any ticks that hitched a ride, and check your body immediately after outdoor activity rather than waiting until bedtime.
If you find an attached tick, remove it with tweezers, grasping near the mouthparts, and watch for fever over the following 30 days. See a healthcare provider if symptoms develop — a single tick bite can transmit more than one pathogen at once.
Key Takeaways
- Powassan virus cases reached 76 in 2025, up from just 7 in 2015, the highest ever recorded.
- The virus can transmit in as little as 15 minutes, far faster than Lyme disease's 16-24 hour window.
- Among symptomatic cases, the fatality rate reaches 15%, and half of survivors face lasting neurological effects.
- There is no treatment or vaccine; care relies on supportive measures only.
- Climate change is extending tick season, a key factor experts cite in rising case counts.
