A DECADE AGO it seemed that malaria, the disease that once regularly reached epidemic proportions throughout much of the world, would soon be conquered. In 1955, after the disease had struck 250 million people, killing over 2 million, the World Health Organization launched a worldwide malaria eradication program. The effort was extraordinarily successful. By 1965 the number of malaria cases had dropped a low of 107 million. In recent years, however, officials of WHO and the U.N. Environment Program (UNEP) report, the incidence of malaria has risen sharply - over 1 million people died from it in 1976. The United States has scarcely been affected by the increase (the number of reported cases here rose by only 100 in 1976-77). But an outbreak of malaria can have a devastating effect on countries in Africa, Asia, and South America - which is where sharp increases have occurred.

In fact the resurgence of this deadly disease stems from the very success of the attempts to eradicate it. UNEP officials say that the malaria parasite, after 20 years of concentrated exposure to attack, has become immune to what were the most effective anti-malaria drugs and that most species of malaria-carrying mosquitos are becoming immune to insecticides.Fortunately, these separate developments haven't occurred in the same geographical areas - yet.

Since the damage done to the environment by DDT and other mosquito insecticides now prevent their use on a widespread scale, how can the spread of malaria be checked? The development of probably the most effective anti-malaria weapon, a vaccine, is still years away. So, the temporary answer appears to be using a variety of different methods to control mosquitos, such as draining swamps, stocking mosquito-breeding waters with fish that eat their larvae, and chemically sterilizing the insects. Each of these methods has its limitations, but at the moment they're all that's available. The resurgence of malarie poses a threat to world health perhaps even greater than that which prompted the WHO eradication program of the 1950s. A new, more technologically sophisticated eradication effort needs to be mounted now. That is what has prompted discussions in recent months between officials of UNEP, which will sponsor the project, and WHO, which will provide the doctors and researchers to carry it out. They well realize the urgency of such an effort. Millions of lives depend on it.