The drug company Pfizer says it will give enough medicine free of charge to treat about ninety percent of people with trachoma（沙眼）. This eye infection is the leading cause of preventable blindness. An estimated one-hundred-fifty-million people have trachoma. Most live in developing nations.

Pfizer said from New York that it will give away one-hundred-thirty-five-million treatments of Zithromax over the next five years. Pfizer invented this antibiotic drug and holds the patent rights until two-thousand-six. After that, other companies can make their own versions. One dose of Zithromax a year can prevent a trachoma infection from progressing.

Pfizer's new donation will help the World Health Organization with its goal to end trachoma by two-thousand-twenty. Joseph Cook heads the W-H-O's International Trachoma Initiative. He says the success over the past five years proves that the goal is within reach.

Since nineteen-ninety-nine, Pfizer has given away eight-million doses of Zithromax to the W-H-O campaign. The nine countries already in the program include Ethiopia, Ghana, Mali, Morocco and Nepal. The other are Niger, Sudan, Tanzania and Vietnam. Initiative officials say the effort will expand to at least ten more countries. The Washington Post reported that Senegal and Mauritania are the next to be added.

Antibiotics are not the only method for dealing with trachoma. The World Health Organization supports a program known as the "SAFE Strategy." "S" stands for surgical operations, for the most severe cases. "A" stands for antibiotics, such as Zithromax. "F" stands for face washing, to reduce the spread of the disease. And "E" stands for environmental changes. These include the development of clean water supplies and better living conditions.

Trachoma begins as a bacterial infection inside the upper eyelids（眼瞼）. Hands, clothes or insects that have touched fluid from the eyes or nose of an infected person can spread the disease. Children and women are at greatest risk -- women, because they are often around children.

Trachoma has blinded about six-million people. Blindness usually happens during the most economically productive years of life. You can learn more on the Internet at trachoma-dot-o-r-g.

This VOA Special English Development Report was written by Jill Moss. I'm Robert Cohen.