A full year after Lisa Gebler, 9, came home from school with a tiny black tick buried in her forearm, the fourth grader is still suffering the lingering effects of Lyme disease, a tick-borne bacterial infection that can cause an unusual form of arthritis and occasionally cardiac and neurologic complications.

Two other children from the same Charles County school have since tested positive for Lyme and a fourth has some of the symptoms: a rash on the trunk area which appears about two weeks after the tick bite and then disappears by itself, frequently followed by increasingly severe bouts of fever and joint or neck pain.

About 90 percent of the 1,500 reported cases of Lyme disease in the United States in 1984 were from seven states: Wisconsin, Minnesota, New York, New Jersey, Rhode Island, Massachusetts and Connecticut (where the disease was first discovered about a decade ago). But officials at the Centers for Disease Control in Atlanta say the number of reported cases in Maryland is up significantly since 1982, when only one case was reported.

In 1983, five cases were reported in Maryland, followed by 12 in 1984, the last year for which figures are available, said Dr. Carol Ciesielski, an epidemiologist with CDC's meningitis and special pathogens branch. The District has yet to report a case of Lyme disease, while Virginia health officials list one case so far in 1986.

But because the disease's serious complications appear weeks, months or even years after the original tick bite -- and then often mimic flu, juvenile arthritis, aseptic meningitis and even mononucleosis -- health officials say many more people may be suffering from Lyme without knowing it.

Left untreated, about 60 percent of those infected develop arthritis -- although it may not be chronic arthritis -- usually within six to eight months after the encounter with the tick.

Another 15 percent of those infected, but untreated, will develop some type of neurologic disorder like viral meningitis, encephalitis or Bell's palsy, a partial collapse of the facial muscles, said the CDC's Ciesielski. Still another 8 percent of untreated adults and children will develop heart problems, notably palpitations.

Only one death has been attributed to Lyme disease, and health officials emphasize that the disease is very treatable, especially if caught early. Lisa Gebler's story is almost a textbook case. Late in May 1985, Lisa, now 10, came home with a tick embedded in her arm.

Her mother took her to the family physician as a precautionary measure. No treatment was prescribed at that time, but by the middle of June, Lisa had developed an unusual red patch at the center of her chest, and it seemed to grow bigger each day.

Her mother took her back to the doctor. "The doctors thought she'd been bitten by a mosquito and put her on Benedryl for an allergic reaction," said Lisa's mother, Mary Anne Gebler.

The characteristic rash, known as erythema chronicum migrans (ECM), went away, but in August and again in November, Lisa suffered short, intensely painful bouts of arthritis. Her knees became swollen and warm, and the normally active third grader went to bed with a fever and a sore neck.

Finally, after a particularly severe arthritic episode last February, Lisa was referred to Children's Hospital, where she was admitted and immediately started on massive intravenous doses of penicillin to kill the bacterial spirochete that causes the illness.

"Hers was a classic case of Lyme disease," said Lisa's physician, Dr. Robert N. Lipnick, a rheumatologist who specializes in juvenile arthritis. "But about 40 percent of the children with Lyme's never get the rash," he said.

If they do, it usually starts with a single spot at the site of the tick bite, which then typically moves to the chest or trunk area, always with a bright red border and clear center.

Lisa is home now, but she is still on anti-inflammatory drugs for arthritis attacks, which are now shorter and less intense.

Identifying and naming this newest of tick-borne illnesses began in 1975, when two observant mothers from Lyme and Old Lyme, Conn., independently called state health officials to question the high number of arthritic conditions diagnosed among their families or neighborhood children.

"One woman said she knew of 11 different children on her road who all had been diagnosed with juvenile rheumatoid arthritis (JRA). The other woman had information on 30 neighbors and family members with similar joint disease," said Elise Taylor, a researcher with the Yale University team eventually called in to investigate.

Through interviews with afflicted individuals, Dr. Allen C. Steere and his colleagues at Yale discovered all had be bitten by a tick. Eventually, Steere was able to link the complex of arthritic, neurologic and cardiac symptoms to a spirochete primarily carried by two varieties of deer tick: Ixodes dammini and Ixodes pacificus.

Researchers are still trying to learn why Lyme arthritis strikes only about 60 percent of those exposed and why this and other symptoms may take years to manifest themselves. Scientists are still not sure why the spirochete seems to congregate in the joints of some people and attack heart tissue or the neurological system of others.

Until more is known, Lipnick says, "awareness is the key. Early recognition and treatment of Lyme's may prevent or substantially weaken subsequent arthritis."

Joan McQueeney Mitric is a writer living in Kensington.