The Prince George's County teachers union, concerned about exposure of special education teachers to contagious diseases, asked the Board of Education last night to take protective steps, including keeping some children with infectious illnesses out of school.

Paul Pinsky, president of the Prince George's County Educators Association, asked the board to develop a policy to protect teachers from exposure to hepatitis, herpes, cytomegalovirus (CMV) and AIDs.

He said the teachers should be given free preventive vaccines and diagnostic tests, parents of other children and teachers should be notified of potential infection and pregnant teachers should be transferred away from certain duties. The union also asked for better gloves for their teachers and that orderlies be hired to help lift heavy children.

"We expect the board to exhaust all avenues to find an alternative place" for students who may be carrying dangerous illnesses, Pinsky said.

The board brought up the topic because special education teachers in the county were concerned about a student known to carry CMV.

CMV is a common virus, present in about 60 percent of the general population, according to the county Health Department. Dr. Robert H. Drachman, a Health Department official, said persons with CMV may experience a mild, flu-like illness, but usually show no symptoms.

The concern about the virus was raised because, if a pregnant woman is exposed, CMV can, in rare cases, cause malformation of the fetus, Drachman said. But he noted that in a study of 58,000 births in Maryland, only 13 children were born with abnormalities caused by CMV exposure.

"The concern about it is rather misplaced since it is so prevalent in the population," Drachman said. "To exclude a child is just not justified."

He also said that, because of the common occurrence of the virus, some medical authorities are no longer suggesting that pregnant women be kept away from CMV carriers because exposure is just as likely from the general population.

Florence Fenton, supervisor of health services for the county schools, said children with infectious diseases have been dealt with on an individual basis and pregnant women have been kept away from students with CMV. Board attorney Paul Nussbaum said school officials "would be wise" to give pregnant teachers a chance to avoid duties that may expose them to the virus.

In other action, the board elected Angelo Castelli as its new chairman and Sarah Johnson its vice chairman. Castelli, who served the past year as vice chairman, replaces Bonnie Johns, who retired from the board this year.