A tuberculosis case reported last month at an Arlington County school has prompted health officials there to consider changes in the county tuberculosis control program, but officials say the case at Key Elementary School in no way indicates an epidemic.

Dr. Marjorie Hughes, chief of child health for Arlington, said the case does not suggest a sudden increase in the incidence of tuberculosis, but rather that "our surveillance has not been as tight as it should be."

So far, Hughes said, health officials have not decided the specific changes that will be made in the county's tuberculosis control program.

All 597 students at Key were tested for tuberculosis after a school employe was found to have the disease last month. Of those tested, 93 showed positive reactions. A positive reaction to the TB skin test indicates the presence of the tuberculosis germ, but does not necessarily mean the person has an active and communicable case of TB. All but one of the 93 Key students have undergone chest X-rays, and none appears to have active TB, Hughes said.

Hughes said health officials decided to test the Key students even though the employe's disease probably was not contagious. "It was highly unlikely that he could have infected anyone, but we don't take that chance," she said.

Hughes said the situation at Key is not unique, and that active TB cases occasionally have been discovered in county schools. "Every now and then an employe or a student turns up with active TB, and then we go in and test everyone in the school," she said. "In none of the cases over the years . . . have we found a second active case tracked back to the first."

Tuberculosis became a primary concern of Arlington health officials in 1975, with the first major influx of Indochinese refugees.

Tuberculosis presented a serious problem in refugee transit camps in Indochina, where crowded conditions and the poor health of many refugees may have contributed to a TB rate that sometimes went as high as 475 cases per 100,000 people, said Dr. Raymond Schwartz, chief of health services in Arlington. Although all refugees were to have been screened for TB before entering the United States, some cases went undetected because children were not always routinely tested in the transit camps, he said.

In 1975, the number of TB cases in Arlington jumped from 14-16 new cases per 100,000 people in previous years to 25 per 100,000. In 1981, there were 77 new cases per 100,000 people. The disease primarily has been a problem among refugees, Schwartz said, while the incidence among native residents has remained stable. A slightly lower rate of new cases is expected this year because fewer refugees are coming to Arlington, he said.

The Arlington situation contrasts with that in Fairfax. Although the rate recently has increased slightly, it still is lower than it was 10 years ago, said Dr. Fred Payne, assistant director of health for Fairfax.

In Alexandria, which also has had fewer refugees than Arlington, TB is a greater problem among native residents than among immigrants, said Dr. Anne Albertson, director of public health for the county. Health officials there said the TB rate has increased recently, although exact numbers are not currently available.

Schwartz said he feels Arlington has had success in dealing with the disease, primarily because of the county's TB control program and the drugs now available to treat the disease.

"We have had concern about tuberculosis from the time of the first inmigration, but we feel it is very thoroughly and very adequately contained," he said.

Early in 1975, Arlington health officials began a program to screen immigrants for tuberculosis. Now, as immigrants arrive from Indochina, Afghanistan and other parts of the world, health officials and volunteers attempt to locate them and refer them to the public health service's TB clinic for testing. In addition, the county makes an intensive effort to keep track of people being treated for the disease. Alexandria and Fairfax have similar programs.

In addition, the county schools have a voluntary TB testing program for eighth grade students, and about 85 percent of the students take the test each year, Schwartz said.