What Is the Powassan Virus (And Should You Worry)?

deer tick
If you've been bitten by a deer tick like this one, the telltale symptom of Lyme disease is a red, circular bulls-eye rash that appears five to 14 days after infection. Steven Ellingson/Shutterstock

Warm weather brings worries of tick-borne illnesses like Lyme disease. But a lesser-known virus called Powassan — also spread by ticks — is making headlines. The disease is very rare, but it can be life threatening.

The virus is named after Powassan, Ontario, where it was first discovered in 1958.

There have only been 75 cases of Powassan reported in the United States over the past 10 years, according to the Centers for Disease Control and Prevention. Most have occurred in the Great Lakes and Northeast region. But because warm weather means more ticks, experts are predicting that the number of cases of tick-borne illnesses, including Powassan, will increase.

Indeed, there have been two confirmed reports of Powassan in New York state, with a third suspected. Previously, there had only been 24 cases of the virus across the state since 2000. The state is increasing its surveillance and testing of ticks.

Here's what you need to know about the virus.

How it's transmitted

People become infected with the Powassan virus from the bite of a tick. The virus is transmitted by three types of ticks, including the deer tick (also known as the black-legged tick), which also can spread Lyme disease. It can't be spread from person to person.

Symptoms and treatment

Many people who are bitten by ticks infected with Powassan won't get sick and won't have any symptoms. For those who do get sick, symptoms can be mild or severe and start appearing any time from one week to one month after the bite occurs. Symptoms can include:

  • Fever
  • Headache
  • Vomiting
  • Weakness
  • Confusion
  • Coordination issues
  • Speech difficulties
  • Seizures

About half of people who have the disease end up with permanent neurological symptoms, such as chronic headaches, muscle loss and memory problems. Powassan virus can also cause encephalitis (inflammation of the brain) and meningitis (inflammation of the membranes surrounding the brain and spinal cord). About 10 percent of Powassan virus encephalitis cases are fatal.

There is no medication to treat the virus. Treatment typically includes IV fluids, respiratory therapies and medication to help if there is swelling on or around the brain.

Powassan prevention

Because there's no vaccine or cure for the virus, prevention is key. The CDC recommends:

  • Avoiding high grass and piles of leaves and walking in the middle of the trail when hiking
  • Use repellent with 20 percent or more DEET, picaridin or IR3535 on exposed skin
  • Treat clothing and gear with products that contain permethrin
  • Shower or bathe as soon as possible after coming inside to wash off ticks and find any before they bite
  • Do a full-body tick check with a mirror as soon as you come inside from tick-infested areas. Remove ticks immediately.
  • Tumble clothes on high heat for 10 minutes to kill ticks when you come indoors.
  • Treat dogs for ticks to protect them and to keep them from bringing ticks into your home.