Two scientists working here have made a dramatic breakthrough that they believe will be of great importance to controlling African sleeping sickness, a major hindrance to agricultural development and food production in vast portions of this continent.

The disease, transmitted by the tsetse fly, attacks thousands of people in Africa each year and kills hundreds of thousands of domesticated animals.

After working on the problem for a year, Dr. S. Hiroyuki Hirumi, a Japanese-born American biologist, and John J. Doyle, a Scottist veterinary researcher, have found a way to propogate and maintain cell cultures of the parasite that causes the disease, the African trypanosome. This is seen as a step toward discovering a vaccine that will immunize against trypanasomiasis, the African sleeping sickness.

Once a vaccine is available, experts say, meat and dairy production in much of Africa should soar, increasing food stocks and improving the diet of millions in some of the continent's most densely settled areas.

This in turn should lead to greater production of other food crops and a resulting higher standard of health, intelligence and productivity.

Presently there is no known control for sleeping sickness, beyond killing the flies that carry it, and drugs for treating its symptoms are relatively ineffective and prohibitively expensive.

Trypanosomiasis will debilitate thousands of new African victims this year in a tropical zone slightly larger than the United States that includes Kenya, Uganda and Zaire.

Most will die within months and many of those whose lives are saved by medical treatment will suffer permanent brain damage.

In the early part of this century a sleeping sickness epidemic wiped out a third of Uganda's population.

Transmitted by the tsetse fly, which bites human and domestic livestock, sleeping sickness is caused by singlecell blood parasites called typanosomes. Some of what is potentially the best grazing land in Africa is virtually unused by cattle because of the presence of the diserse.

This account in part for the startling underdevelopment of some of the most fertile and best-watered parts of the continent. Control of sleeping sickness in human and livestock would accelerate economic progress and raise living standards in many backward areas of Africa, expert believe.

Hirumi and Doyle are attached to the International Laboratory for Research on Animal Diseases, which was established in Nairobi last year. It is jointly funded by 10 governments as well as private and multinational organizations. About 25 per cent of its budget comes from the U.S. Agency for International Development and its work is supported to the Rockfeller Foundation.

The laboratory's director, Dr. James B. Henson, of Washington State University, said: "It is absolutely incredible to have made this discovery in just one year and it will enhance the probability of synthesizing a vaccine to prevent sleeping sickness just like they have done for smallpox and polio."