A virus that peaked during the holidays made the last several weeks a season to be queasy for many Washington area children and kept many doctors busy on days when they don't usually accept appointments, local physicians said yesterday.

Several area pediatricians said their offices have been crowded with children suffering from a seasonal outbreak of gastroenteritis, more commonly known as stomach virus. Those cases, along with children suffering flu and bronchitis, filled some waiting rooms yesterday and kept doctors busy during the holidays.

"This is the height of the gastroenteritis season," said Dr. William Goldman of Arlington. The illness, long ago called "winter vomiting sickness," is caused by a virus with a seasonal peak, Goldman said.

This year, the bug was busiest during the holidays, and, in the past several weeks, Goldman has treated as many as 10 children a day with gastroenteritis symptoms, he said.

"I won't say the illness is an epidemic. But we are seeing increased numbers of cases we feel are probably related to viral infections and a lot of viral gastroenteritis," said Dr. Lillian Beard, a pediatrician in the District.

The illness, which may cause vomiting, diarrhea and fever, is usually treated with a mild diet free of milk products, the doctors said. They said it can last from two days to several weeks, with bouts of three or four days the most typical.

Gastroenteritis is highly contagious; one child with the virus can spread it through a family, a group of friends or a nursery school class, doctors said. "Families will come in where the kids have it and then Mom says, 'You know, I'm feeling a little queasy, too,' " said Beard.

Dr. Albert Spiegel of Fairfax Pediatric Associates rushed through a telephone interview yesterday afternoon before returning to his young patients. "You can see today is busier than this time last year," he said. He said his most frequent cases in the past few weeks were children with "flu, all the aspects of the flu. Sore throat, fever, also vomiting and diarrhea. Every year it happens at different times."

At the Children's Hospital National Medical Center emergency room in Northwest, doctors usually treat one or two children a day with symptoms of gastroenteritis, said associate director Dr. Michael Altieri. But on New Year's Day, about 30 children showed up with signs of the illness, and another 20 had the sore throat, fever and aches typical of flu, he said.

Seasonal sickness swept through the five-member Piansky family of Springfield, and yesterday 4-year-old Jessica and her mother, Debbie, joined the ranks in the colorful, crowded waiting room Goldman shares with two other Arlington pediatricians.

"I wanted to bring her in this morning, but I couldn't even get through" to the doctors, Debbie Piansky said. "When I did, they said, 'Please come in the afternoon. It's a zoo.' "

She said they arrived in the office at 1:40 p.m., 20 minutes before the doctors began afternoon hours. At 4:30, she was still there.

Goldman, who wears a tiny figure in a Redskins uniform clipped to his stethoscope, paused between patients and explained that a diet of clear fluids is the best antidote for the illness. "That, and waiting for it to get over with," he said.