The specter of falling into a sleep from which one cannot awaken has haunted many literary classics from "Snow White" and "Sleeping Beauty" to Rip Van Winkle. The movie "Awakenings" depicts survivors of the great pandemic of "sleeping sickness," or lethargic encephalitis, that swept the globe just after World War I. The patients' dramatic return to normal consciousness, after decades of a catatonic state, came during the summer of 1969 when they were given a new drug, L-dopa, used to treat Parkinson's disease.

Today a new drama of miraculous reawakenings is unfolding in sub-Saharan Africa involving victims of African sleeping sickness, a different disease involving the same symptoms. Ornidyl or eflornithine hydrochloride, the first new drug to treat African sleeping sickness in 40 years, is being hailed by the World Health Organization as a "resurrection drug," because it has cured comatose patients who were considered hopeless and within hours or days of death.

African sleeping sickness is fatal if left untreated. It is caused not by a virus, as was the case with the patients in "Awakenings," but by parasites transmitted by a bite from the tsetse fly. The disease begins with fatigue, fever and intense headache, joint pains and a range of other symptoms. When the protozoa finally invade the central nervous system, victims suffer extreme mental and physical lethargy -- hence the name "sleeping sickness" -- followed by seizures, coma and death.

There are two varieties of African sleeping sickness: the Gambian form common in west and central Africa and the Rhodesian form common in east and southern Africa. Ornidyl is effective only for the Gambian strain.

African sleeping sickness infects approximately 25,000 people annually, according to public health officials at the WHO; the Gambian form is widespread in 36 central and west African countries. Fewer than 10 cases per year usually surface in the United States, most among travelers who have spent a long time in Africa.

Until Ornidyl, developed by the U.S. pharmaceutical company Marion Merrell Dow, there was no safe drug for the late stage of the disease, when the central nervous system is involved. The only treatment was melarsoprol, an arsenic-based drug that killed up to 5 percent of patients treated with it and left a further 5 percent permanently damaged as a result of severe lesions of the central nervous system.

Pentamidine and suramin, other sleeping sickness drugs that have been used to treat some AIDS symptoms, were only effective in the early stages of African sleeping sickness.

One account of treatment provided by the WHO describes the case of a comatose African woman in the advanced stages of the disease who was given Ornidyl intravenously by doctors in a Belgian hospital that specializes in tropical diseases. Two days later, she was conscious and awake. After another week, she was answering questions and walking with help. Within three weeks of receiving the drug, she was able to talk spontaneously, walk without assistance and wash and dress herself. Shortly afterward, she left the hospital and was totally independent. The drug had returned her to a normal life.

Molecular biologists investigating the genetics of the sleeping sickness parasite have recently announced advances in manipulating its genes, leading to hopes for an eventual vaccine.

Unlike the case with African sleeping sickness, no cure or treatment was found for the type of sleeping illness portrayed in "Awakenings." The virus that caused lethargic encephalitis, an inflammation of the brain, was never clearly identified. During the this epidemic, which occurred at the same time as the Great Flu Pandemic of 1918, the illness struck between 5 million and 10 million people worldwide, killing half of them fairly quickly. Many of the sleeping-sickness survivors seemed to recover fully, only to be incapacitated years later by a paralyzing Parkinson's-like syndrome. Curiously, tissue from the encephalitis patients never showed evidence that they had had the flu. Epidemiologists still cannot say whether the two epidemics were connected.

The sleeping sickness epidemic, which began in the Balkans in 1916, ended in 1927 for no apparent reason. Rare cases of post-encephalitic Parkinson's syndrome are seen today, but doctors believe the syndrome is caused by some other more common varieties of encephalitis, not the strange encephalitis lethargica.

Some doctors speculate that the encephalitis lethargica virus is only lying dormant. Oliver Sacks, the New York neurologist who wrote the book "Awakenings" upon which the film was based, warns that there is no reason to think that the mysterious virus is extinct.

In an appendix to his book, he notes a 2,000-year history of past episodes of the disease, including an epidemic in Europe in 1580 and a serious outbreak in London between 1673 and 1675. In Italy, following a famous flu epidemic in 1889-90, "the notorious 'nona' appeared -- a devastatingly severe somnolent illness, which was followed by the development of Parkinsonian and {similar symptoms} in almost all of the few survivors."

Sacks writes that there was probably a small epidemic of the virus in the concentration camp at Theresienstadt during World War II. He also cites repeated reports of sporadic cases appearing around the world in different places.

Smith Ely Jelliffe, a neurologist and psychoanalyst who observed the 1916-27 pandemic closely and wrote about it extensively, says Sacks, "asks again and again how it could happen that a disease which had obviously existed since the days of Hippocrates could be 'discovered' only now, and how it was possible for an illness which had been described unmistakably innumerable times to be 'forgotten' anew by each generation.

"Such forgettings," writes Sacks, "are as dangerous as they are mysterious, for they give us an unwarranted sense of security. In 1927, with the virtual cessation of new cases of encephalitis lethargica, the medical profession heaved a huge sigh of relief."

Richard T. Johnson, director of the department of neurology at Johns Hopkins School of Medicine and neurologist in chief at Johns Hopkins Hospital, sees many patients with Parkinson's-like afflictions and is sent unusual cases from all over the world. Although he is fascinated by the history of encephalitis lethargica, he says, "I don't personally think the disease occurs anymore simply because I have not seen the full-blown disease." Victims of the "Awakenings" epidemic showed peculiar kinds of eye movements and other symptoms that Johnson says he has not encountered.

If the disease were still around, he is confident he would have seen some cases. "It's just these sort of patients who get sent to me," he says.

Were encephalitis lethargica to appear again, says Johnson, scientists would be much better prepared than their colleagues were 75 years ago to stem an epidemic.

"We would be able to isolate a virus and devise a treatment," he says. "At that time, the most they could do was inoculate rabbits and monkeys. There were no cell culture systems, no electron microscope and no molecular methods to look for the virus."Robin Herman is a Washington writer.