VOA慢速英語:經(jīng)化學(xué)藥品處理過的蚊帳可以阻止象皮病的發(fā)生嗎？

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Scientists are working on ways to stop a disease that threatens one-fifth of the world’s population. Over 120 million people are infected with lymphaticfilariasis, also known as elephantiasis. The disease is found mainly inSoutheast Asia and Africa. It affects the lymphatic system, which is a majorpart of the body’s natural defenses for

fighting disease.

Elephantiasis can cause swelling, or enlargement, of skin and tissue. Thecause is a tiny worm that enters and lives in lymphatic tubes for six to eightyears.

Scientists say they have been able to demonstrate that the most commoncause of elephantiasis can be stopped. They are urging those at risk to sleepunder nets treated with chemicals that kill a common insect: the mosquito.

Lisa Reimer teaches at the Liverpool School of Tropical Medicine. Sheformerly served in Papua New Guinea as part of a team studying the disease. The team involved researchers from Papua New Guinea, Britain, Australia and the United States.

A man afflicted with elephantiasis.

Doctor Reimer says she was surprised at how effective anti-malaria bed netscovered with insecticide could be at fighting the disease.

"Filariasis is only picked up by mosquitoes late in the evening, so this is thetime when people are more likely to be protected by their bed nets. So wefound that bed net use actually is a greater barrier against filariasistransmission whereas malaria transmission may still be occurring outside thetimes when the user is under the net."

Doctors normally use drugs to fight the disease. Miz Reimer says doctors inPapua New Guinea gave the drugs to people of five villages. She says thistreatment nearly ended the threat from the worm to humans. But the drugs didnot stop the threat from mosquitoes.

The treated nets block female mosquitoes from securing blood, which isnecessary for them to reproduce. The insecticide also cuts the life of theinsects in half.

"If we can reduce mosquito-biting rates then we're able to increase thethresholds below which the disease prevalence will move to zero. So bycontrolling mosquitoes we're making the targets for the mass drugadministration more obtainable."

The World Health Organization has set a goal of stopping lymphatic filariasisas a public health problem by the year 2020. The WHO estimates that 1.4billion people in 73 countries are at risk of the disease. Children are ofteninfected, but they do not show signs of the disease until later in life.

I’m Bob Doughty.