With a major malaria outbreak sweeping Ethiopia, an international doctors' group working there contends that outdated drugs are being used to fight it and may even worsen the epidemic. Unicef, the United Nations agency providing the drugs, defended the choices it made in consultation with the Ethiopian government.

The older drugs are still effective, it said, and changing policy midepidemic for a health system as battered as Ethiopia's can be disastrous. But an internal World Health Organization memo from Dec. 3, obtained by The New York Times, disagrees and "strongly recommends" that a new but more expensive drug be used. The struggle illustrates problems confronting the makers of world health policy. Drug-resistant strains can evolve faster than new drugs can be discovered, and new cures are inevitably more expensive, forcing choices between costly drugs that work and cheap ones that may not.

The W.H.O. expects Ethiopia's epidemic to spread to 15 million of its 65 million population — triple the normal rate. The aid group arguing for newer drugs, Doctors Without Borders, says that in the two Ethiopian areas where it runs clinics, up to 60 percent of patients have strains that appear resistant to the first-line treatment that Unicef and Ethiopia picked, a two-drug cocktail of chloroquine and sulfadoxine-pyrimethamine, better known by its initials, SP, or the brand name Fansidar. 

The doctors' group said the second-line treatment, hospitalization for five days of quinine, was inaccessible for many patients and hard on malnourished children. Ethiopia is a mountainous country, where many people live far from clinics or are nomadic. Doctors Without Borders wants to introduce artemisinin, a chemical that Chinese herbalists first derived 30 years ago from the sweet wormwood plant. It has become the latest wonder drug against malaria. But it is relatively expensive.

Even at the prices drug companies offer to the poorest countries, cocktails that use it cost $1 to $2.50 an adult treatment. A typical treatment of chloroquine and SP costs about 20 cents. The artemisinin program also requires taking pills for three days instead of one.

Nonetheless, the W.H.O., which usually provides treatment guidance, strongly endorses artemisinin cocktails, which are being used in several African countries, including Burundi, Liberia and South Africa. Because resistance to chloroquine is widespread, the W.H.O. discourages its use. Dr. Kevin Marsh, a malaria expert working in Kenya, called chloroquine "a failed drug" and said health authorities were foolish to spend money on it.

Heavy rains this year ended five years of a drought that starved and weakened people in wide swaths of Ethiopia. The rains were accompanied by unusually hot weather that let mosquitoes breed at higher altitudes. Malaria surged. United Nations relief agencies are calling the outbreak the worst since 1998 and the country's "single biggest health problem."

But malaria death rates in some villages are five times the normal rate, said Dr. Pauline Horrill, an emergency coordinator for Doctors Without Borders. Across the world, malaria kills three children a minute.

This year, Unicef, the United Nations Children's Fund, tried to head off the epidemic by ordering hundreds of thousands of mosquito nets and $1.2 million worth of drugs. Several countries have dropped requests for money for chloroquine and have asked for artemisinin. Nonetheless, the Ethiopian government has refused to let artemisinin be imported.

"The Ministry of Health says the old treatment is still effective," said Ambassador Teruneh Zenna, Ethiopia's deputy permanent representative to the United Nations. "They have been using it for a long time now. They are not against the new treatment, but they have to make controlled experiments to prove it works."

The health chief at Unicef, Dr. Pascal Villeneuve, defended his agency's choice as "a pragmatic approach." Drug companies do not make enough artemisinin to supply all of Ethiopia, the cost is a barrier, and as a United Nations agency, Unicef has to follow the lead of the host country, he said.

"National policies are not an issue that should be taken lightly," he said. Dr. Kent Campbell, a malaria expert for Unicef, said chloroquine was still effective against vivax malaria, which is less fatal than more predominant falciparum malaria, but persists in Ethiopia. Artemisinin "wouldn't hurt," Dr. Campbell said. "But it wouldn't change the number of people dying." No program, he added, should be changed based on "anecdotal data" from two sites run by Doctors Without Borders. Dr. Villeneuve, Dr. Campbell and two other United Nations malaria specialists declined to say in a joint telephone interview whether they agreed with Ethiopia's policy or were lobbying to change it. At the time they were interviewed, they did not know about the W.H.O. memo disagreeing with them. A Unicef spokesman said late yesterday that there was "nothing religious" about Unicef's position and "we want proper science to guide the decision-making here."

Dr. Horrill called Ethiopia's position "frustrating and very difficult to understand." Also, she argued, using SP in an epidemic may actually speed the spread of malaria. The drug attacks one phase of the life cycle of the malaria parasite, but stimulates the production of gametocyte cells that mosquitoes can pick up and spread to others.

By contrast, artemisinin gives "rapid cure and rapid knockdown of the epidemic," Dr. Horrill said. Dr. Campbell said the spread of the epidemic could be slowed by insecticide-impregnated mosquito nets. If the resistance levels detected by Doctors Without Borders are widespread, using artemisinin "would be a sensible strategy to follow," said Dr. Mary Ettling, chief malaria expert at the United States Agency for International Development.

The United States, which has contributed more than $2 million to fight the Ethiopian epidemic, now endorses using artemisinin in many African countries, in the Amazon Basin and in the Mekong Delta of Vietnam. That is a policy change from 18 months ago, when the United States generally opposed its use in Africa.

At the time, a Usaid malaria adviser said, artemisinin was too expensive, came in multiple regimens that were difficult to take and needed more testing in children. Regimens are now simpler, and the drug can be given even to dehydrated, malnourished children.