美國之音2007標(biāo)準(zhǔn)下半年AResearchers in Kenya Discover New Weapon Again

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Researchers in Kenya Discover New Weapon Against Malaria

By Caroline Sawyer
Nairobi
09 August 2007

Researchers in Kisumu, on the shores of Lake Victoria, were studying insects and the environment when they discovered that by introducing a fish called the Nile Tilapia into ponds, mosquito numbers fell by more than 94 percent in less than a year.

These results are potentially life saving for local residents because malaria, which is spread through the bites of infected mosquitoes, kills more people here than any other disease.

According to the World Health Organization (WHO), approximately 40 percent of the world's population is at risk from the disease. In sub-Saharan Africa, malaria, which is caused by a parasite, is responsible for over 3,000 deaths every day. The majority of victims are children under five years old.

Senior scientist from the International Center of Insect Physiology and Ecology, Dr. Francois Omlin is leading the Nile Tilapia study. He is working in an area where 15 years ago, fish farming was a booming industry. Omlin says the farming business collapsed leaving only stagnant water behind which is ideal for mosquito breeding.

"We were shocked to see how many malaria larvae were there and felt it was critical to reactivate those fish ponds," he noted. "Of course, for that the ideal thing is to have a fish that is not only a good larvae eater, but also [the types] people like to eat, and the farmers can make an income [with]."

The number of people suffering from malaria has increased dramatically in the last 10 years. Scientists say this is partly due to the parasite's ability to become resistant to drugs, but they add that population movements and climate change also contribute to the rise. Researchers are working on a vaccine, but progress has been slow.

The most effective way to prevent malaria is by sleeping under insecticide-treated bed nets, but many poor people in Sub-Saharan Africa cannot afford them.

Omlin's research on the Nile Tilapia published Thursday warns that this particular fish will not be able to help everyone.

"One has to operate with indigenous fish in order not to destroy or to affect the ecological balance in the environment," he explained. "One has to go local in a proper sense specific to find out which fish species are ideal and then make some very simple tests with that fish. Is that fish useful to the people? Do they like it for eating? Is it a good mosquito vacuum cleaner?"

Omlin says he hopes his work will encourage research on other indigenous fish that could help in other parts of the world. The United Nations estimates that malaria costs African countries $12 billion annually.