Doctors in the Northeast and Great Lakes regions are warning Americans of a rare tick-borne illness they say is more serious than Lyme disease. Nobody is known to have contracted the Powassan virus yet this year, but it has been found recently in ticks in Bridgeport and North Branford, Connecticut. Officials are urging people to be vigilant as they head into summer, when ticks tend to be most active.

The acute symptoms of the Powassan virus affect victims for up to a month and can include vomiting, seizures, memory loss and swelling in the brain. The virus often requires patients be hospitalized, and it leaves about half of those infected with lasting neurological symptoms, according to the Centers for Disease Control and Prevention. No vaccines or medications currently can treat the infection. The Powassan virus gets transmitted when an infected tick bites a person. Humans cannot spread it. 

Daniel Cameron, president of the International Lyme and Associated Diseases Society, told CBS New York that people can start seeing symptoms of the virus minutes after being bitten. Lyme disease transmission typically takes longer than Powassan. "You can get seizures, high fevers, stiff neck. It comes on so suddenly that it's the kind of thing people go to the emergency room for," he said. "The doctor just has to support you during the acute illness and hope that you survive."

Anyone who gets bitten by a tick in areas where the virus is found is at risk, according to the CDC, but the virus is rare. Over the past 10 years, only about 60 people have gotten the Powassan virus. There were 12 cases in 2013 and seven in 2012 -- far less than the 25,000 cases of Lyme disease reported each year. "To put it in perspective, the tick infection rate with that virus is quite low," Tom Mather, director of the University of Rhode Island's Center for Vector-Borne Disease, told in 2013.

People hoping to protect themselves can use tick repellent and wear long sleeves and long pants when walking in wooded areas. The CDC recommends taking a bath right after being outside and checking your entire body immediately.