Although most Washington area schools do not appear to be experiencing abnormally high absenteeism, Children's Hospital - which sees more sick children than any other hospital in the area - reports that it is "swamped with calls and swamped with patients" having flu-like illnesses.

Dr. Edward Hein, chief outpatient resident at the hospital, said that the number of cases and the type - a stomach ailment referred to a "reovirus" and an upper-respiratory influenza known as Influenza B or Hong Kong - are what normally appear at this time of year. The only unusual part, according to Hein, is that the flu usually strikes hardest in December and January. "This year, it's late," he said.

The incidence of both types of influenza. Hein said, is running at roughly the same rate as last year and the year before. The hospital has seen no cases of A/Victoria or swine flue, he said.

Dr. Martin Levy, chief of the communicable diseas control branch of the District's Department of Human Resources, said that the flu "doesn't appear to be any major problem."

Holy Redeemer Elementary School in Montgomery County, however, canceled classes yesterday and today after 110 of its 396 students became ill. Sister Mary Alicia, principal of the school, said the problem had "gotten progressively worse over a 10-day period."

Hein said persons with the virus should be treated with fluids, aspirin or an aspirin substitute for fever. If fever persists for more than 48 hours, he said, a physician should be consulted to make sure that the patient is neither dehydrated nor suffering from some other infection.