CALAIS, Vt. - Kent Morse remembers the horrible sick feeling that gripped him as he shaved that February morning, followed by the sweet relief of lying immobile on the floor, his face still covered in lather.

For two weeks, the 61-year-old state employee and part-time farmer edged closer to death, his lungs filling with fluid, his heart, liver and kidneys failing one by one. Not even specialists contacted at the famed Mayo Clinic could figure out what was wrong. "It was like he was running a marathon every day just trying to breathe," said Dr. Sandy Craig, one of Morse's physicians.

Two months later, Morse was confirmed as the first person in New England to contract a hantavirus, one of the most frightening infectious diseases to emerge in the last decade.

Epidemiologists originally discovered and isolated the disease in the Southwest in 1993 after 33 people, mostly vigorous young adults, fell suddenly and seriously ill. Within days - sometimes hours - 17 were dead from a ravaging virus that is carried by mice.

Now, the US Department of Agriculture has turned Morse's garage into a makeshift lab where two Vermont field biologists are preparing mice trapped in the house and nearby woods for testing at the Centers for Disease Control in Atlanta. They suspect that Morse contracted the virus when he disturbed a mouse nest in a wood pile, directly inhaling infected feces or urine.

Morse doesn't remember much of his three-week hospitalization except horrible nightmares about being beaten up and trying to get home. And medical experts still don't know why he survived.

Public health officials stress that the rarity of cases such as Morse's show that people have less reason to fear hantavirus outbreaks than once thought. They stress that people can only contract a hantavirus in rare, unlucky circumstances.

But the more sobering message is that - since 8 percent of deer and white-footed mice throughout the United States are infected - the often-lethal disease can show up almost anywhere.

"It was just a matter of time before HPS [hantavirus pulmonary syndrome] was diagnosed in Vermont," said Dr. James Mills, chief of the CDC's Medical Ecology Unit.

So far, 250 people - including 30 cases contracted before the 1993 Southwest outbreak - have been diagnosed with one of about 10 hantavirus variants in the United States. Many more cases have gone undetected, probably confused with influenza or adult pulmonary distress syndrome, especially in the East, where hantavirus is less expected.

"Vermont has had it before," said Dr. Charles Calisher, professor of microbiology at Colorado State University and a 27-year veteran of the CDC. "You can bet on it. And probably somebody has died."

Yet, awareness of hantavirus infection is so low in the East that neither Morse nor the many doctors who examined him thought of it. Specialists ran the desperately ill man through a gantlet of tests, put him on a ventilator and pumped him full of antibiotics. Nothing seemed to stop the disease.

Morse's symptoms - extreme difficulty breathing, organ failure - fit, but, except for a fatal 1994 case in Rhode Island thought to have originated in New York, hantavirus infection had never been confirmed in New England.

"All those experts and they never thought of hanta. Only Dr. Craig," Morse said.

And Craig put the puzzle together only after Morse recovered. The doctor called colleagues in Vermont to order a hantavirus test from a beach in Bali where he was vacationing.

That's a far cry from seven years ago, when the mysterious outbreak in the Southwest made national headlines, and some feared it was a strain of the bubonic plague. Despite panicky headlines, Centers for Disease Control researchers quickly ruled out the disease that killed more than 100 million people in Europe, Asia and North Africa in the Middle Ages. For one thing, they said, hantaviruses are far-less contagious.

An unusual set of circumstances had triggered that first known hantavirus pulmonary syndrome outbreak. Although the mice in the region had long carried the virus, an especially wet spring set the stage by producing a bumper crop of pinyon seeds that mice eat. The seeds spawned a mouse population explosion, greatly increasing the risk that people would come into contact with infected mouse feces or urine.

Still, only 33 people contracted the disease. "If it were easily transmitted," said Mills of the Centers for Disease Control, "mammologists who study rodents would be dropping dead all over the US. We don't understand why some people get sick and some don't. It's mysterious."

Hantavirus is also frightening, especially since the disease favors healthy young people, turning their healthy immune systems into a weapon against them. As their bodies fight the hantavirus infecting lung cells, their immune response destroyed the capillary walls, causing their lungs to fill with fluid.

Vermont state epidemiologist Peter Galbraith sees the first homegrown New England hantavirus infection as a chance to educate New Englanders about how to minimize their risks. The virus is short-lived, especially in air or sunlight, and easily killed, he said. Before cleaning an area contaminated with mouse droppings, people should wet it down with a solution of bleach and water, put on rubber gloves, and then dispose of the material in double plastic bags. They should not sweep or vacuum.

For his part, Morse doesn't have to be told never to stir up a mouse nest. "The doctor asked me if I was an athlete," he said. " 'No,' I told him, 'but I was raised on the farm and always worked hard.' He told me that if my heart hadn't been so strong I'd be dead."