Sudan is the largest country in Africa and one of the poorest in the world. The southern region of the country is very remote and was devastated by a civil war that went on for nearly half a century, with only short intervals of peace.
An international team of researchers conducted a survey in May 2005 in Mankien—a district of Sudan with a total population estimated to be around 50,000. Their aim was to estimate how many people were blind or had ‘‘low vision’’ and to find out the main causes. Working under very difficult conditions, the researchers selected villages to be visited at random. A house in each village visited was selected by spinning a pen in the middle of the village. The people in this house were examined and then other houses were chosen, also at random. Around 2500 people were examined. Children under five years were not included in survey. A very high rate of blindness was found—4%. This is more than twice the level that would be expected, given what is known about the prevalence of blindness in other parts of rural Africa. The two most common causes of blindness and low vision were cataract and trachoma, each accounting for over one-third of cases. Trachoma, which is caused by an infection, was responsible for a greater proportion of the cases of blindness than has been found in studies in other parts of rural Africa.
In a second survey in the same district, the researchers looked specifically for cases of trachoma, both in its early stages and later when it has led to blindness. Some 3500 people were examined, of whom 2000 were children aged less than 15 years. The earliest stages of infection were very common indeed, particularly in children aged 1–9, over half of whom had some sign of infection. In adults, one in five had trichiasis caused by trachoma.
Trachoma can be passed from one person to another through contact with hands and clothes, and by flies. The disease develops gradually—while children are most susceptible to infection, they may not note its effects until adulthood, when scarring from repeated infections causes the eyelashes to turn inward (‘‘trichiasis’’). The cornea—the transparent front part of the eye—becomes damaged by the eyelashes and develops ulcers, and eventually blindness results.
The situation revealed by the researchers is particularly tragic as improved living conditions, better hygiene, and early treatment of the infection with antibiotics can prevent trachoma. Surgery for trichiasis is also very effective. The World Health Organization recommends a strategy for trachoma control known as ‘SAFE’: surgery, antibiotics, facial cleanliness, and environmental change. The authors call for its urgent implementation in southern Sudan.
The surveys are also discussed in two ‘Perspective’ articles in the same issue of PLoS Medicine. One article discusses the possibility that the methods used in these (and other) health surveys could over-estimate the level of blindness.
Andrew Hyde | EurekAlert!
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