Johnny Bigley toddles into his empty classroom in a school in suburban Anne Arundel County, wearing a red and white stocking cap and swinging his red book bag.

With his pixie face and outgoing manner, the 3-year-old looks like a typical little boy as he makes a beeline for the kitchen area's pots and pans, unaware that he is at the center of a controversy.

Johnny has herpes simplex, an incurable and contagious viral disease that causes periodic blisters on his hands and back.

Because of his affliction, Johnny's teacher and his five classmates in a preschool special education class did not attend class last week. So he and a substitute teacher spent Johnny's first mornings as a pupil in a classroom by themselves. The Teachers' Association of Anne Arundel County has asked a circuit court judge to bar the boy from school until safeguards can be approved by the county school board.

The Millersville, Md., youngster is one of three small children unwittingly involved in an emotional and nationally publicized uproar surrounding herpes. In Council Bluffs, Iowa, a teachers group recently asked a judge to bar a 3-year-old girl with herpes simplex from attending school. In Sacramento, Calif., last week, parents picketed a school attended by a 4-year-old boy who has a common flu-like form of herpes that does not result in lesions or, much of the time, other outward symptoms.

On one side of the dispute are parents and teachers who believe that they have legitimate health concerns -- doctors cannot say why some people contract herpes and some do not, and there is no known cure.

"We're scared that Christopher will be that one-in-a-million child that will come down with something that will harm him," said Brenda Evans, mother of a child in Johnny's class. " . . . I think what scares me -- and maybe it's just my problem and I'll have to deal with it -- when I think of herpes, I think of around the mouth or around the genital area. If I can't deal with it, I can't ask my son to deal with it. Every time he gets on that bus I would wonder."

On the other side of the dispute are doctors and other medical experts who say the public does not understand what herpes is, how frequently it occurs, or how easily and often a child is exposed to the virus.

"People are frightened out of their wits about something they can't do anything about," said Dr. Mervyn Elgart, chairman of the dermatology department at George Washington University medical school. " Johnny Bigley is certainly not the only person walking around with something on his hands."

Pat Randall, a spokeswoman for the National Institutes of Health, concurs. "What people don't realize is that herpes is everywhere," she said.

"Most people have it and don't even realize they have it," Randall continued. "If we were to do blood tests on everybody, at least 70 percent of the population would show evidence of having been infected. But if you were to ask them, they'd say, 'Oh, no! I don't have herpes.' "

Mention herpes and people automatically think of the most notorious of the herpes viruses -- herpes simplex II or genital herpes, usually transmitted through sexual contact and suffered by about 20 million Americans. The prevailing concern is that herpes can infect a baby if lesions are present in the mother's birth canal when the baby is being born, but instances of infection are rare.

In Maryland, for example, from 1978 to 1982, only 11 children contracted herpes at birth, according to state health officials. Officials say half of the children infected with herpes at birth die soon after, while the rest suffer permanent damage to the eyes or nervous system.

Herpes is a family of four viruses that can cause diseases ranging from the familiar cold, or canker, sore (herpes simplex I) to infectious mononucleosis, chicken pox, shingles and cytomegalovirus (CMV). Most of these viruses do not cause serious problems except in infants and persons who have eczema or weakened immune systems.

The Sacramento child is infected with CMV, which has flu-like symptoms and, in newborn infants, can be associated with hearing loss and brain damage. The case came to light when a school staff worker apparently read the child's medical record last fall, saw the word herpes and told others that a child infected with herpes was due to be enrolled in special education classes in January, said Dr. Paul Hom, health officer for Sacramento County.

"For the vast majority of people, CMV means nothing. There are no clinical manifestations at all," Hom said. "By the time we become adults, we've all been exposed to it. The irony is, at every school in the U.S., there's some kid who has CMV.

"In this case, there was more harm done to the kid, the worried parents and the school than that one virus could ever have done," he said.

In Iowa, the Council Bluffs child has periodic herpes outbreaks on her torso, said Dr. James A. Blackman, a professor and pediatrician at the University of Iowa Medical School, who is familiar with the case.

In that situation, "the whole issue of the mother's morality came into play with the public," Blackman said.

Once again, the public assumed genital herpes, although the mother said she apparently gave the child herpes by kissing the baby when the mother had a cold sore on her mouth, Blackman said.

At a court hearing on whether the child should be allowed to attend school, Blackman and other doctors said the child posed no danger to the teacher or other children if certain precautions were taken.

Blackman assisted in drawing up a policy for Iowa schools to use in dealing with children with herpes, the first such set of guidelines in the country and the model for safeguards in Johnny Bigley's case set out last week in a preliminary hearing by Circuit Court Judge Eugene M. Lerner.

At the top of the list is frequent handwashing with an antiseptic cleanser. Also, in Johnny's case, he must play with a separate set of toys that are to be washed down at the end of each class. Special precautions will be taken during diaper changes, which are necessary because Johnny is behind in his development. The changer must wear rubber gloves and a gown and do the changing in a separate room.

How Johnny contracted herpes remains a mystery. Based on medical information provided by the parents, it is most likely that he suffers from Type I, and not so-called genital herpes, because he was delivered by Caesarean section and neither of his parents has been told that they have herpes, said Dr. Polly Roberts, a pediatrician with the Maryland state health department.

He apparently got the disease shortly after he was born three months premature and weighing a little over three pounds. He was not breathing at birth, but doctors were able to resuscitate him and transported him to a Baltimore city hospital's neonatal unit.

No one has determined at what point Johnny got the disease or from whom, said his father Edward Bigley, a businessman. But within days of his birth, it was determined that Johnny had herpes on his back and hands. A speech defect that necessitates Johnny's involvement in early special education classes is a result of the premature birth and not the herpes, Bigley said.

Johnny's lesions, which resemble mosquito bites, have decreased in number and frequency over the past three years, his father said. The boy's last outbreak was in October. Medical experts say the earlier herpes is contracted, the more likely a person will build up immunity and outgrow the lesions, so the Bigleys hope that Johnny's condition will improve.

Johnny's brother has been tested and does not have herpes, Bigley said. Also, the family's friends and neighbors, along with Johnny's eight to 10 playmates, have shown no signs of the disease.

To protect themselves, the family uses "very simple procedures in hygiene" such as washing hands before eating, Bigley said.

"You do not get the virus by standing next to someone," he said. "It's not something you can casually get." The virus is spread by pus from the victim's lesions entering a crack in someone else's skin or through the mucous membranes.

"The fact of the matter is, people are probably more at risk from other children because we know John has it and we take care of it," Bigley said.

Despite the uproar, Bigley said he feels no animosity toward the parents of Johnny's classmates.

"We want to protect our children," he said. "We all do."

But, he added, "From a philosophical standpoint, we can't in 1985 live in a sealed glass jar. Johnny has herpes and millions and millions of others do, too. He will overcome it. Society will accept John, but people have to be educated."

Bigley said he agreed to talk publicly about his son's problem for just that reason.

"I'm trying to desensitize society," he said. "If you are a parent that gives a damn about your kids, you help them the best you can.

"It seemed to me that the great fear was the fear of the unknown."