Marilyn Ruth Snow visited her local hospital on Nov. 9 with a tiny, stubborn tick embedded in her shoulder blade.

Two days later, the active and healthy 73-year-old, a Rockland area watercolor artist better known as Lyn, would speak her last coherent words with her family.

“After that she became delirious and she was in and out of consciousness,” said her daughter Susie Whittington. “Then she was gone.”

Snow, of South Thomaston, died last Wednesday at Maine Medical Center in Portland. The next day, test results confirmed the rare Powassan virus in her body, making Snow Maine’s first documented case of the often deadly tick-borne disease in nearly a decade.

Nationally, just 50 cases of the Powassan virus have been reported over the past 10 years.

Snow’s family wants others to be aware of the disease, a viral infection first recognized in the town of Powassan, Ontario, in 1958. The virus can cause fever, headache, vomiting, weakness, confusion and seizures and may also lead to brain swelling, a devastating complication that kills 10 percent of those who develop it, according to the U.S. Centers for Disease Control and Prevention. Snow was among the 10 percent.

About half of those who survive the infection suffer permanent neurological symptoms such as memory problems, facial tics and blurred vision. There is no vaccine or treatment other than keeping patients comfortable and hydrated during hospitalization.

Snow, who walked 3 miles a day and never smoked nor drank caffeine, rapidly slipped away, her daughter said. She was put on a ventilator within 12 hours of arriving at Maine Medical Center and remained at the hospital for five weeks, enduring septic shock and other complications, Whittington said.

“It was horrific,” Whittington said. “I watched her get sick before my eyes as we had these specialists watching her like hawks. She had amazing care but there was nothing that could be done.”

Snow also received antibiotics for Lyme disease, a bacterial infection similarly spread through the bite of an infected tick. Lyme disease’s telltale bull’s-eye rash had appeared on her shoulder blade and she had been bitten another time in late October, but Snow’s health providers soon suspected a virus, Whittington said.

Because the antibiotic treatment can interfere with Lyme test results, Snow’s family doesn’t know if she contracted both Lyme and Powassan.

“It is much more deadly than Lyme, and people need to be aware of that,” Whittington said. “We want people to protect themselves.”

Powassan is distinct from the much more common Lyme disease in several ways. In addition to being caused by a virus rather than a bacterium, Powassan spreads in two strains, through the bite of both the deer tick, Lyme’s preferred host; and the woodchuck tick.

Both strains cause the same symptoms in humans.

So named because they’re often found on woodchucks, woodchuck ticks appear across Maine, also inhabiting skunks, weasels and rodents, according to Charles Lubelczyk, a field biologist with Maine Medical Center Research Institute’s Vector-borne Disease Laboratory.

The eight-legged ticks — which look nearly identical to deer ticks to the naked eye — don’t “quest” for hosts like deer ticks, so people are less likely to come across them while enjoying the outdoors, he said.

“When people encounter them, they tend to bump into them near the burrows of animals,” he said.

Maine last recorded Powassan in humans between 1999 and 2004, when the state documented four cases of the virus, Lubelczyk said. Powassan also has been detected in Maine deer and moose, though the virus doesn’t appear to sicken the animals, he said.

In tick-dense areas of Maine along the midcoast to York County, an estimated 50 percent to 70 percent of adult deer ticks are infected with Lyme. But researchers lack data on how many ticks carry Powassan, he said.

“We know that it’s around,” Lubelczyk said. “Now why it would suddenly decide to pop up this year as opposed to last year or the year before, we don’t really know.”

He expects Maine hasn’t seen the last of the virus.

“I suspect, although I don’t know, that we’ll probably see more of it as the years go by, especially since it’s now appearing in deer ticks,” Lubelczyk said. “In potential areas, it’s really kind of a game-changer, as far as tick-borne diseases go.”

Public health officials believe Powassan is more common in Maine than the documented cases suggest. Some patients never get diagnosed or tested, preventing the Maine CDC from ever learning of the illness, said Director Sheila Pinette.

Unlike Lyme, Powassan isn’t “reportable,” meaning health providers aren’t required to notify the CDC of Powassan cases, she said. Maine CDC is working to change that, she said.

“We really believe that the numbers are low,” she said. “We feel there’s a lot of underreporting.”

Some people infected with the virus don’t experience symptoms, according to the U.S. CDC. The incubation period, or time from the tick bite to the beginning of illness, ranges from about a week to a month.

“It’s not commonly part of the battery of tests that [doctors] would order, but we’re encouraging physicians, for patients complaining of fatigue, fever, and meningitislike symptoms, that they order this test,” Pinette said.

While ticks need 24 hours to transmit Lyme, “with Powassan we’re not certain how long the tick needs to be attached to transmit the disease,” she said.

Whittington, who lives in the Kennebec County town of Mount Vernon on 12 acres of designated deer yard, urged Mainers to check themselves for ticks after time in the outdoors. Every time.

“Living in Maine is such a gift … We don’t have poisonous snakes, we don’t have poisonous bugs, but we do have ticks,” she said.

Avoiding ticks: Tips from the CDC

Choose light-colored clothing so it’s easier to spot ticks; wear long sleeves and and tuck your pants into your socks.Use an EPA-approved insect repellent .Check your skin and clothing for ticks and remove them promptly. Don’t miss warm, moist areas such as the ears, armpits and neck, and have someone else check your back.Wash possible tick bites with soap and water and apply an antiseptic.Keep your lawn mowed and tidy to remove tick habitat.If you spot an embedded tick, use tweezers to grasp its mouth and pull it out with steady pressure. Don’t use petroleum jelly, hot matches or nail polish remover, which can increase the risk of infection.If a tick isn’t engorged with blood, it’s less likely it has transmitted disease.