A young student, exposed to the AIDS virus through contaminated blood transfusions, presents no threat to the public and can attend school with classmates, the D.C. Board of Education ruled yesterday.

The youth, who has been instructed alone in a separate classroom since school began last month, can join classmates immediately, the board ruled. The student's mother informed school officials before the start of the school year about her child's exposure.

The board's action came after D.C. Public Health Commissioner Andrew McBride and a special medical panel confirmed the student had been exposed to the virus, but was not suffering from the illness. The youth, who is a hemophiliac, was exposed by using blood products containing the AIDS virus.

Scientists estimate that 5 percent to 10 percent of those exposed to the virus will develop acquired immune deficiency syndrome within five years. About 25 percent of those exposed may develop an AIDS-related disease. It is not known how many of those exposed to the virus have the capability to transmit the virus to others, but experts say the virus has only been transmitted by sexual contact, sharing of needles and blood transfusions.

"The student's health is to be reviewed periodically by [the child's] personal physician and the school nurse," said school spokeswoman Janis Cromer.

The student's teachers and other school personnel will be informed of the child's exposure, but the school system will not disclose the name of the child or the child's school for fear of provoking unwarranted isolation of or attention toward the student, Cromer said.

The medical panel that made its recommendations to McBride included experts in blood diseases and cancer affecting children, as well as specialists in immunology, infectious diseases, pediatric medicine and pediatric psychology.

Some panel members physically examined the child, according to Charles Siegel, spokesman for the Department of Human Services.

The child's medical records and tests were evaluated by the entire panel, which concluded the child posed no danger to classmates or teachers.

In his recommendations to the school board, Commissioner McBride said the schools should implement "routine procedures for the handling of body fluids."