Here's what to know about the tick-borne disease.

Former North Carolina senator Kay Hagan died Monday at the age of 66, the Washington Post reports. Hagan, who was the first Democratic female senator to represent the state, died in her home in Greensboro, North Carolina.

"We are heartbroken to share that Kay left us unexpectedly this morning,” her family said in a statement, according to the Charlotte Observer.

Hagan's death comes three years after she was diagnosed with Powassan virus in 2016, after being hospitalized with encephalitis (swelling of the brain). People can contract Powassan virus via tick bites, Health previously reported. Ticks infected with the virus can infect humans in just 15 minutes.

Powassan virus “is a rare, uncommon condition that we are only beginning to learn about and understand,” Alan Taege, MD, an infectious disease expert at Cleveland Clinic previously told Health. In fact, the first two Powassan virus cases in the United States were recorded just over a decade ago, in 2008, per the CDC. Since then, the number of annual cases reported has varied; it's been as low as two and as high as 33.

Some people who contract Powassan virus don’t experience any symptoms, but others become seriously ill. The time it takes for the virus to produce symptoms varies—they could show up from one week to one month after the bite occurs. Symptoms include encephalitis, which Hagan suffered from, and meningitis, which is inflammation of the lining of the spinal cord and brain. Additional symptoms include weakness, fever, vomiting, headache, confusion, speech difficulties, seizures, and loss of coordination.

Ten percent of Powassan virus cases are fatal, and about half of the people who contract it experience symptoms from it for the rest of their lives. Hagan herself had a long, difficult recovery from the virus. According to Fox News, after being diagnosed in 2016, it wasn't until mid–2017 when she started to show signs of improvement. "[She] clearly understands what people say to her and recognizes her friends when they come to visit," her family said at the time.

Unfortunately, there’s no known cure for Powassan virus, and there's no vaccine for it. But patients with the virus can benefit from supportive care. Those with severe disease may need to be hospitalized.

That said, you can take some steps to prevent yourself from getting the virus from a tick in the first place. Wearing long pants and long-sleeved shirts can help you avoid getting bitten by ticks when you’re hiking or camping, or just hanging out outdoors. Additionally, wearing light colors can help you avoid ticks (because you’ll be able to spot ticks more easily if they’re on your clothes). Wearing bug spray and checking yourself for ticks frequently can also help you lower your chances of contracting and suffering from Powassan virus.

To get our top stories delivered to your inbox, sign up for the Healthy Living newsletter