Laura Mitchell is your "every day, normal 6-year-old first grader," her mother said, the youngest of five. And "when you have teen-agers," Terry Mitchell added, "you really appreciate the age 6."

They get a lot of flu in a family of five. Sighed Tom Mitchell, "Sometimes I think we have a monopoly on it."

Laura got flu in November, the second member of the family to have it.

By now they've all had it. But Laura had something else too. Something called Reye's syndrome.

They've closed schools in Michigan this week in panic. "We think," a frightened mother there wailed, "the health people know more than they're telling us . . ." There has been a cluster of Reye's victims in the Battle Creek area -- 25 cases, four deaths.

"It comes one of the most serious new diseases and nobody really has a handle on it," said Sen. John Melcher (D-Mont.) who is sponsoring a bill to fund research on Reye's syndrome.

"You don't want to panic people," said Dr. Joel Taubin, a Washington-area physician whose 11-year-old son died of Reye's two years ago, "but too many people think it's such a rare disease. It's here. It's not rare."

There have been half a dozen cases and at least one death reported in the metropolitan Washington area this winter, only about half as many as by this time last year. Monday night a six-year-old died in Baltimore at the Johns Hopkins University Hospital. Of Reye's syndrome.

"Laura's flu ran its course," Terry Mitchell said, but "the next morning she has this violent, violent, violent vomiting . . . I remember I had read this article, so I called Georgetown-Reston and took her right over. She was almost comatose by the time we got there, with her eyes rolled back in her head. I had to shake her to get her up. They did a liver test and her enzymes were way out of whack . . . They sent us to Dr. Colon at Georgetown. She was in Level-I Reye's."

Dr. Angel R. Colon, associate professor of pediatrics at Georgetwon Medical Center, has been conducting research on Reye's since 1971.

He will concede first that Reye's is a mystery illness, then tell you that "it is a disease of the mid-20th century," given a name (after Australian pathologist R. Douglas Reye, who described the symptoms) only in 1963.

The symptoms are "so overt," Dr. Colon said, that "it is difficult for me to conceive that the great French and German pathologists of the 19th century could have missed this disease" if it had been around then.

"There is just no similar description before 1950 or so."

Dr. Colon suspects that the disease is caused by an interaction of virus and a toxin -- some poison in the environment from an insecticide, perhaps, or even one occurring naturally. In this county Reye's is usually, although not always, associated with either chicken pox or the type-B flu virus, which is the one around this year. It hits as the patient appears to be recovering, mostly affecting children under 19. However, it has been identified in adults as well.

Although there are pockets of research, there is no concerted national research effort on Reye's syndrome, something Sen. Melcher hopes to change. About one flu victim in 1,000 appears susceptible, said Dr. Colon, "so when you add up the thousands of children who come down with flu and the cases of Reye's, it is not common. But it is such a devastating one when it hits."

Gregory Mark Taubin, 11 years old, was president of his sixth grade class at Potomac Elementary School in the Maryland suburbs. He was an honor student and a promising athlete. He was recovering from chicken pox.

Dr. Taubin remembers it was a Saturday and he'd gone to his downtown office to see patients and there had been a phone call from his wife. "She said, "There's something wrong with Greg. He's not acting right. He's screaming and yelling . . .'"

Greg had what Dr. Colon characterizes as "malignant Reye's." He had no chance.

In the wake of his own tragedy, Dr. Taubin has made his office in downtown Washington the headquarters for the local Reye's Syndrome Foundation, a chapter of a national grassroots organization founded in Bryan, Ohio, by the parents of a victim. Taubin has just been made a member of the board of trustees.

He is tireless in his crusade to inform, to scare up research funds, to advise, to comfort. He sends letters describing symptoms to fellow physicians and lobbies for a federal program. He warns that it can be mistaken for others things. Adolescents with Reye's may act like drug users, for example. He has distributed a poster to hospital emergency rooms urging personnel to "Consider Reye's."

The Midwest seems to have more Reye's cases than other parts of the country.In Ohio, where some 100 cases have been reported, physicians "are so tuned in," said Dr. Colon, that more cases are getting earlier treatment and the death rate there has been considerably reduced.

One thing the doctors have learned from observing Reye's victims is that its course takes it through five distinct levels, ranging from mild symptoms to deep coma. When it attacks, Dr. Colon said, "it is like a tornado in the body. It wreaks havoc. It starts in the liver, affects the kidneys, the heart, the pancreas, the body muscles and then creates brain swelling. Then suddenly the liver starts to heal and it has left in its wake this tremendous damage all over the place, the main one being the bain swelling."

The overall mortality rate of Reye's syndrome is a frightening 40 percent. But if the disease is caught early enough, that rate can be reduced to only about 10 to 15 percent. Doctors feel certain that Reye's is not contagious, although the viral diseases it follows usually are.

"At first,' said Terry Mitchell, "they told us we should watch Laura for any neurological signs overnight, but then Dr. Colon said it wouldn't be fair to put that responsibility on us so we took her into the hospital. They woke her every 15 minutes to make sure she knew who she was . . . where she was, did neurological tests . . . You wonder when you see all those extraordinary precautions, but Dr. Colon sat us down and said, 'About 15 percent come in like this and die . . . ."

Reye's syndrome will come on something like this: The victim appears to be getting over a bout with chicken pox, a cold, flu or gastroenteritis. Usually he will then go into relentless nausea and vomiting, accompanied, or followed, by listlessness, lack of pep, and neurological changes, including personality or behavior changes, unusual irritability, combativeness or inappropriate responses.

"The main thing," said Dr. Colon, "is to let parents know, look, if your kid has what looks like a cold and starts to vomit, has either lethargy or disorientation . . . that's the time to hightail it to a doctor, because from there on in, it can just blow out . . ."

The treatment of Reye's must be what doctors call "aggressive," with a specialized Reye's team prepared to take heroic measures as the course of the illness requires. Dr. Colon feels strongly that the illness must be treated at a hospital where doctors and nurses are trained in the specific kind of intensive care a Reye's victim usually requires.

Most important in the treatment is the use of a device implanted by a neurosurgeon to measure brain pressure. If the disease progresses to the later stages, the neurosurgeon may have to perform further surgery to relieve the pressure, ultimately the cause of death.

But even earlier as the disease ravages other organs, specialists -- nephrologists, cardiologists and neurologists -- must be on hand to counter the crises that can follow each other minute by minute.

Even when a patient recovers, Dr. Colon said, there is a 30 percent chance of "residual neurological change," ranging from a mild learning disability to severe retardation.

"We feel we have a debt," said computer firm executive Tom Mitchell. "I'm giving out leaflets on street corners," said Terry Mitchell, a Northern Virginia Realtor.

Laura Mitchell's illness never went beyond the early stages and she appears to have suffered no ill effects. "You don't know how fortunate you are,' they told me" Terry Mitchell said. "I look very closely at my children now."

Laura is a perceptive child, her mother said, and didn't miss the implications of the hospital procedures and probably of conversations going on around her.

"When she first came home, she wouldn't take off the hospital bracelet," Terry Mitchell said. "She would say, 'Everybody got one . . . I survived.'"