Treating African children at home for malaria doesn't help in cities because most fevers aren't actually caused by malaria, a new study said Tuesday.

Malaria drugs were distributed to households where parents had been told by researchers to automatically treat their children if they became feverish.

Roughly half the children were treated at home while the other half were taken to health clinics within a day of developing a fever.

To effectively treat malaria, children must be treated within a day of getting sick. The study found that children at home got twice as many medicines as those taken to clinics, but didn't do any better.

The research highlights holes in malaria treatment across the continent and raises questions about an upcoming U.N. initiative to fight the disease.

Experts monitored more than 400 children aged between 1 and 6 in Kampala, Uganda, from 2005-2007.

The research was published online Tuesday in the medical journal, Lancet. It was paid for by the Gates Malaria Partnership.

Malaria, which is spread by mosquito bites and carries symptoms such as fever, chills and vomiting, primarily affects poor people in remote areas.

Some doctors said the study showed a worrying tendency to treat fevers before they were diagnosed as malaria.

"If you just go on fever, you're over-treating so many children and you could miss other diseases by using malaria drugs," said Dr. Tido von-Schoen Angerer of Medecins Sans Frontieres, aka Doctors Without Borders. He was not linked to the study.

Malaria medicines don't work on fevers caused by other diseases like pneumonia, and children can die if they are not properly treated.

Previous studies have found home treatment works in rural areas. But malaria is also a problem in cities, and will have to be tackled differently there than in the countryside.

Von-Schoen Angerer said the Lancet study underlined that standard care for malaria in Africa is appalling.

Despite decades of work and renewed U.N. efforts to combat the disease, only 5 percent of children in Uganda are promptly treated with effective medication. Across Africa, the World Health Organization puts the figure at 3 percent.

WHO estimates malaria sickens about 247 million people and kills nearly 1 million every year.

Later this week, the United Nations and partners will announce a $200 million strategy called the Affordable Medicines Facility for Malaria to make drugs cheaper in 11 African countries.

Von-Schoen Angerer and others worry the tendency to over-treat malaria, as proven by the Lancet study, will be worsened by the strategy. They fear it will flood the market with drugs that promote resistance.

The initiative, led by WHO and the Global Fund to fight AIDS, tuberculosis and malaria, will subsidize the price of artemesinin combination therapies, the most effective malaria treatments.

But the U.N. has not insisted the drugs be combined in a single pill, which would curb the resistance risk.

Artemesinin combination therapies are also sold as several pills. Some cause side effects like nausea, and patients commonly throw those pills out, encouraging resistance.

"The risk of resistance is very scary," von-Schoen Angerer said. "We don't have a back-up medicine at this stage."

Richard Tren, director of the nonprofit Africa Fighting Malaria, called the U.N. initiative "an untested experiment," and warned the strategy could backfire.

"We need policies based on evidence," he said. "And the evidence this could work is pretty shaky."