Betty Malone was sitting in the living room of her mobile home in eastern Fairfax County, chatting on the telephone, when her 7-year-old son interrupted her.

He had just come from classes at Riverside Elementary School, and he handed her an envelope marked "Priority." Malone, the telephone still pressed against her ear, tore it open and began reading. "My God," she said. "The AIDS child is in our school."

In the past month, Malone has emerged as the unofficial leader of a small but determined band of about 30 Fairfax County parents who -- despite assurances from health authorities that AIDS patients pose no significant risk to students or staff members -- do not want them in the classroom.

Fairfax officials and residents are attempting to draft policy guidelines that would apply to students and teachers suffering from AIDS. The Riverside AIDS child, a girl in kindergarten, is believed to be the only student in the Fairfax system suffering from the disease. The Riverside case drew widespread attention after school officials temporarily removed the girl from class.

In recent weeks, Malone has appeared on local television, been interviewed on the radio and held parent meetings, and said she has fielded more than 100 supportive telephone calls from worried Fairfax parents who feel as she does. "We've been putting out fliers everywhere -- in malls, stores, on windshields."

Support for Malone's efforts has been spotty, school officials have said. Most Riverside parents understand that AIDS cannot be transmitted through casual contact, said Riverside PTA President William E. Herker.

"I've only had a couple of calls from parents who are upset, and they belong to Mrs. Malone's group," he said.

Malone would rather err on the side of caution. She worries about blood from children's wounds, or from lost baby teeth, and about saliva left on drinking fountains, and shared toys.

"The Bible teaches us, 'Suffer ye not your little children,' and when you put your children out there, knowing that possibly they can get AIDS, are we not letting our children suffer?"

She has withdrawn her two children from Riverside, and enrolled them at a private academy, which she said is not only free of AIDS, but also of drugs and alcohol -- other items of concern.

Malone said she feared for her son's health, but more so for her 5-year-old daughter, who attended a morning kindergarten session in the same classroom used each afternoon by the sick child.

To afford the $270-a-month tuition at the private school, Malone has taken a job with a telemarketing firm. Her husband, Ray, a night security guard, is moonlighting as a public school cafeteria worker.

Malone will not divulge her children's names, the name of their new school or other details because she said she does not want to involve family members or employers in what has become a personal cause.

She grew up in the tiny town of Sophia, W.Va., outside of Beckley. Her father, a Baptist pastor and coal miner, eventually left the mountains to seek another job.

He found one here, driving a truck for a building supply company, and moved his family north to Falls Church when Malone was 12. She was graduated from Falls Church High School in 1966.

She has been involved in various jobs and activities since then, including Head Start volunteer. Malone's belief in the importance of children's education has made her role in the AIDS fight that much more difficult, she said.

"I have a very strong feeling for this little girl," she said. "Even though I don't know her, I've seen her."

Before withdrawing her son and daughter from Riverside Elementary, Malone said she tried her best to explain to them about AIDS precautions.

"I tried to explain to the kindergartener not to go near a child when it had an open wound, and she couldn't understand," Malone said. "And my little boy -- the 7-yearold -- looked at me and said, 'If AIDS kills, I don't want to go back to that school because I don't want to get AIDS.'

"I mean, what do you tell a child? I mean, what kind of parent would I be if I lied to my child? I gave him the straight, honest facts as good as I could give him."

Malone objects to news accounts that she claims have portrayed her as an unsympathetic "nut" on an emotional "witch hunt."

"These AIDS children -- they're sick children," she said. "They need help."

Her solution would be to establish special facilities for children and teachers suffering from AIDS. "Instead of letting AIDS teachers die on the payroll, why not let AIDS teachers work with AIDS children? These teachers better understand how these children feel because they're both facing death."

"I'm not saying put them out in solitude by themselves," she added. "They could set up special classrooms for these children, where they're not exposed to chicken pox, mumps, measles, croup, flu viruses -- and, in turn, our children wouldn't be exposed to AIDS."

Malone said it's not easy to take what appears to be an unpopular stance, but said she has received compassion and respect from her family. She also is cheered by her supporters -- people such as Brenda Handy, a Fairfax mother of two public school students.

"I think it's her principles and her strength that really draw us to her," said Handy. "Because it took a hell of a lot of strength to come out against this. A lot of strength."

"I never expected to be doing what I'm doing now," said Malone. "It just started out that I was getting phone call after phone call, and parents were saying 'What can we do?' and the next thing I knew, we were forming a group."