Eighty percent of annual malaria deaths occur in Africa

NAIROBI, Kenya (CNN) -- Researchers in Africa say an anti-malarial vaccine is needed to combat the disease that kills between one-and-a-half and three million people worldwide every year -- 80 percent of them in Africa.

African health officials are at a loss over how to best fight malaria. The disease is carried by mosquitoes, which lay eggs in still waters and feed off blood. Once the carrier has delivered the parasite to the human host, the parasite can mature and reproduce.

The life cycle of the infecting parasite varies according to the species, which means an infected patient can suffer bouts of malaria for years. Researchers say the parasite is a complex organism that is even more difficult to deal with than HIV, the virus that causes AIDS.

The mosquitoes can survive insecticides, and some of the parasites have grown resistant to chloroquine, a commonly prescribed treatment for malaria.

"The tools that are at hand are actually blunt, so therefore we need new tools," said Wen Kilama, a researcher in Tanzania.

Vaccine tested in Tanzania

Kilama and some of his colleagues say an anti-malarial vaccine could be the best tool for fighting the killer disease. But scientists warn that it may be five to 10 years, if not longer, before an effective vaccine is developed.

Malaria is carried by mosquitoes, which lay eggs in still water and feed on blood

A synthetic vaccine called SPF 66, invented in Colombia, was recently tested on about 600 Tanzanian children aged 1 to 5.

Doctors say SPF 66 proved safe, but protected only about one-third of the vaccinated children.

The drug already has been in development for 10 years.

Research and development costs are expensive, but experts in the sub-Saharan African countries, the region of the world most-affected by malaria, warn that a vaccine must be inexpensive.

"If you got a vaccine that is not affordable, it would not be useful because malaria is so widespread," said Dr. Richard Muga, Kenya's top medical officer.

Rate of killer disease on the rise

Under normal conditions, malaria annually causes more deaths in Kenya than the world's top killer, tuberculosis, or even AIDS.

U.S. Army and Kenyan government researchers work together to improve a vaccine

Weather conditions also contribute to the spread of the disease. Thie year, heavy rains blamed on El Nino sparked a malaria epidemic in Kenya that killed hundreds of people.

Health officials in Zambia and Zimbabwe say the number of people who contract malaria annually is rising at an alarming rate. In Zambia, the rate has doubled in 10 years. Zimbabwe has seen an even sharper increase.

"We would normally get 300 to 500 deaths annually from malaria," said Dr. Timothy Stamps, Zimbabwe's health minister. "Two years ago, we got over 2,000. This last season, the figure is around 1,700."

Nairobi Bureau Chief Catherine Bond contributed to this report.

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