Egyptian scientists are launching a concerted attack against a disease that since the era of the pharoahs has been known as the scourge of Egypt - bilharzia.

Bilharzia is a debilitating parasitical disease that is eroding the kidneys, livers and bladders of half the Egyptian population, inflicting pain and death.

Bilharzia, or schistosomiasis, is as much a part of Egyptian life as the Nile. Centuries of struggle against its ravages have produced neither mass cure nor effective vaccine. Innumerable international conferences and intensive studies have chipped away at it here and there, but the disease still rages unchecked through most of rural Egypt.

This year the Egyptians, with West German help, are opening yet another front in the war against bilharzia.A 120-bed research hospital devoted exclusively to this disease will be opened in Cairo, giving the country its first modern, integrated center for experimentation, treatment and study of bilharzia.

The hospital will be known as the Theodor Bilharz Institute, for the German scientist who came to Egypt in the 1850s and identified the tiny worms that cause the malady that now bears his name.

Dr. Ahmed Garem, a professor of tropical medicine at Cairo University who was recently chosen by the National Academy of Science as the institute's first director, said its creation "will give us a very high standard of laboratory work on the site where the disease exists."

What it will not do, he said, is wipe out the disease or discover any miracle drug to treat it. That, he said, is because bilharzia by its nature "is not just a medical problem but a social, agricultural, behavioral, socioeconomic and informational problem." A vaccine, he said, "is still a dream, and so is a safe, easy nontoxic medication."

Egypt is getting help from West Germany, the United States, the World Bank, the World Health Organization and other groups in its efforts to combat one of the most widespread and serious ailments in the tropical world. But as Dr. Garem indicated, it would require a massive realignment of the behavioral patterns of agricultural Egypt to get rid of bilharzia altogether.

Bilharzia is no mystery, since there are dozens of specialists in Egypt who know what causes it, how to cure specific cases and even how to eradicate it. The dual problem this country faces is the massive scale on which the disease has infected the population and the Egyptian pattern of rural life that perpetuates it.

The disease is caused by parasitic worms, called schistosomes, that live in the intestines and urinary tract of humans. They burrow and penetrate the tissue, eroding the bladder, liver, kidneys, bowels and other organs. The result is loss of blood, lethargy, hepatitis, premature aging, brain damage, bladder cancer and eventual death, if not from the disease itself then from weakened resistance to other infections.

The worms breed in waterborne snails that thrive in warm, slow-moving waters like those found in Egypt's irrigation canals. Egyptian villagers drink the canal water, bathe themselves and their animals in it, use it to water their crops, launder their clothes in it and now, in summer, swim in it. Since the worms can quickly penetrate the skin, a brief dip can result in a lifelong infestation.

"It's not true that there is no cure," Dr. Garem said, "I have cured people in my laboratory. But there are millions of them, and the problem is reinfection. You can cure an individual case, but then he goes back to his village and back into the canal." In many rural villages, he said, "you can go into a class room at a boys' school and you will see that 90 to 100 percent are invested."

The Bilharz Institute, which will have the kind of facilities for study and laboratory work in hematology, urology, parasitology and immunology that are hard to find in African countries, will "provide scientific answers to some of the many questions," Dr. Garem said. But it will not get little boys to stop diving into the canals on hot afternoons.

Nor will it get rid of the snails. In efforts to do that, the Egyptians have tried everything from planting snail-killing weeks to spreading a lethal powder developed in West Germany, but their local successes have not lead to eradication of the snails.

The Chinese solved a similar health problem by a massive program of draining their canals and sending armies of workers in to pick out the snails one by one with chopsticks, according to medical reports, but easy-going Egypt does not lend itself to that kind of mobilization.

As Dr. Garem noted, it is one thing to pipe potable water into the villages, as Egypt has done. It is another thing to get the Egyptians to line up at the tap instead of dipping their buckets into the canals as they always have.

Officials of the Ministry of Health have calculated that the disease costs Egypt about $400 million a year in direct costs and in lost man-hours. In addition, police officials blame bilharzia for the widespread use of hashish and other drugs among the male population as Egyptian men look for some antidote to the pain, lethargy and loss of sexual potency that it inflicts on them.