Fairfax County's decision last week to exclude children with acquired immune deficiency syndrome from school highlights a growing national problem for educators: how to balance the concern that school children be safe from disease with the belief that all children have a right to a public education.

Like their counterparts in Fairfax County, officials from Montgomery County and the District last week frantically began trying to set a policy for students with the deadly disease, and other jurisdictions also are beginning to grapple with the problem. The issue has become imperative in the District, because school officials decided this summer to bar from classes a student with AIDS-Related-Complex, which is caused by the AIDS virus and may develop into AIDS. The student, a hemophiliac who was exposed to the ARC virus through a blood transfusion, is receiving separate instruction in school.

Educators are finding AIDS an emotional issue that escapes easy answers. Although everyone agrees the disease is contagious, the debate centers on how it is spread.

"It seems that last year it was herpes and this year it's AIDS," said Ruth Harris, president of the District of Columbia Parent-Teachers Association. "We all know this is something we have to think about."

"What has happened in New York has brought the problem into the forefront," said Vicki Rafel, president of the Montgomery County Council of Parent-Teachers Associations, referring to the decision by thousands of New York City parents to keep their children out of school rather than let them attend class with a child who has AIDS. "I hope what is happening there doesn't happen here. We need to come with a definitive answer, because students need to be safe."

Federal health authorities from the Centers for Disease Control have issued guidelines advising that AIDS cannot be spread through casual contact and children with the disease should not be excluded from school. But many doctors and educators believe that children should not be exposed to others with AIDS until more is known about the disease and how it is spread.

"It's like the polio scare, when people thought you could catch polio if you went swimming," said Harris. "We really have to think about AIDS. We have to find out as much as we can about it."

Fairfax County is the only local school system to announce a policy on AIDS. On Thursday, Superintendent Robert R. Spillane told the county School Board that he will exclude any pupils with AIDS because Virginia law bars children with contagious diseases from school. Spillane said employes with AIDS would not be permitted to remain in the schools.

He said he decided to spell out how the school system will deal with AIDS because parents are worried about the problem.

Mary Collier, chairman of the Fairfax County School Board, explained: "The parents who have called me are reading stories in the papers, and there is a lot of confusion. No one knows how AIDS is transmitted, and until we know we can't take a risk."

The day that Fairfax County announced its policy on AIDS, a District school board committee recommended that the city follow the guidelines suggested by federal health officials and let children with AIDS attend school until a permanent policy is adopted.

The full school board is expected to vote on the interim policy soon.

In Montgomery County, School Board President Robert Shoenberg asked school officials last week to develop a policy to deal with students and staff members who have AIDS. School officials are working on one, said Edward Masood, who coordinates health services for the Montgomery County school system.

"We want to be in a position where we can make a policy in the absence of emotionalism and public pressure," he said.

Masood said that policy recommendations for the board, which are expected next month, probably will follow the Centers for Disease Control's guidelines.

"Legally, I would be offended by someone removing a child for no reason if everyone was telling me the disease could not be transmitted casually," said James Cronin, vice president of the Montgomery County Board of Education. He added that teachers with the disease should not be dismissed, but should be given assignments that do not involve contact with children.

Prince George's County public schools will consider each AIDS case individually, declared Dr. Floss Fenton, supervisor of health services for the school system.

Gail Nuckols, president of the Arlington County School Board, said county school officials are working on AIDS guidelines, but have not yet decided what they will be.

"I think you can stem the tide of some of the hysteria if you are prepared," Nuckols said.

Robert Peebles, superintendent of the Alexandria public school system, said that he will follow the state's policy, which would exclude from school any child with a contagious disease.

"But individual cases would be evaluated by the local department of health," Peebles said, "and readmission to the schools would depend on their recommendation."

AIDS is a disease that destroys the body's immune system, leaving it vulnerable to infections and other diseases. Doctors at the Centers for Disease Control believe that AIDS is spread only through sexual contact and blood transfusions, but the virus has been discovered in the tears and saliva of those who have the disease, leading to the fear by some physicans, parents and teachers that the disease could be spread by children at school.

"Students cough, sneeze, have runny noses," said Collier of the Fairfax County school system.

So far, most cases of AIDS have been among homosexual men, drug abusers, hemophiliacs and the children of AIDS victims.

In the past year, the issue has created conflict at several school systems, including the controversy in Queens, N.Y., where thousands of angry parents kept their children out of school to protest a judge's decision to let a 7-year-old with AIDS attend second grade. In a case in Kokomo, Ind., parents of a 13-year-old boy with AIDS filed suit against the school system after the boy was denied admittance.

There have been no reported cases of school-age children with AIDS in Virginia or Maryland, health officials said.

Virginia and Maryland state health officials said they are working on guidelines so school districts will know how to deal with AIDS.

"We're trying to develop a policy," said Dr. Joseph Horman, chairman of the AIDS task force with the Maryland State Department of Health. "My hope is it won't take months, but we can't be sure how many modifications will have to be made."

Casey Riley, director of the sexually transmitted diseases program at the Virginia Department of Health, said guidelines on AIDS in the schools will be issued within a month. Although the Virginia guidelines will be patterned after the federal ones, which recommend that AIDS victims be allowed to attend school, Riley said, each school system will have to decide whether to admit a student with AIDS.

But Harry L. Smith, a spokesman for the Virginia Department of Education, said that the department will send a memorandum to state school superintendents on AIDS next week, informing them that Virginia law stipulates that children with infectious diseases may not attend school.

The memorandum, signed by state Superintendent S. John Davis, says, "Such exclusion should be made pursuant to local school board policy developed after consultation with the appropriate medical and legal authorities."

Should a student be excluded from school because of a contagious disease, the memorandum continues, "every reasonable effort should be made to provide homebound instruction . . . . "

As more school systems search for a fair policy to deal with AIDS, legal questions are likely to arise. Fairfax County officials acknowledge that their policy of excluding children with AIDS may be tested in the courts.

"I don't fear the challenge," said School Board chairman Collier. "Until parents are sure there is solid evidence that body secretions don't transmit AIDS, they don't want their children exposed to AIDS."