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The Global Burden of Trachoma
6 Nov 2009
Citation: Burton MJ, Mabey DCW (2009). The Global Burden of Trachoma: A Review. PLoS Negl Trop Dis 3(10): e460.
2009 Burton, Mabey
The biggest infectious cause of blindness, trachoma, is the subject of a review article in PLoS Neglected Tropical Diseases. The authors – Matthew Burton and David Mabey from the London School of Hygiene & Tropical Medicine – describe the condition and discuss the various estimates that have been made as to the prevalence of the disease worldwide and of its impact.
The article includes a map showing the countries where trachoma is endemic. Predominantly these are in Africa, the Middle East and Asia. There is a lack of reliable data from most of these countries but WHO now estimates that 1.3 million people in 56 nations are currently living with blindness due to the disease.
A further 1.8 million have low vision as a result of trachoma, and trichiasis (the ingrowing of eyelashes that is caused by trachoma and will eventually lead to blindness) afflicts a further 8.2 million. The latest WHO estimate of the disease burden in terms of disability-adjusted life years (DALYs) is 1.3 million. The authors caution, however, that this may be an underestimate as some of the health effects of trachoma have not been allowed for in the calculations.
Burton and Mabey also examine the estimates made of the economic burden due to trachoma. These have ranged from $2.9 billion to $5.3 billion. In calculating the higher of these figures, it was assumed that trachoma-blinded individuals experienced a 100% loss of productivity, whereas the lower estimated assumed a 60% loss. If trichiasis is also included the economic loss is an estimated $8bn. As the article points out, there are many difficulties in making calculations of this kind. All we can be sure of is that the human and economic costs of trachoma are vast.
In contrast, the calculations of the cost-effectiveness of the four elements of the “SAFE” strategy for the prevention of trachoma are probably more reliable. (The four components of SAFE are surgery for trichiasis, antibiotics for infection, facial cleanliness, and environmental improvements to reduce transmission.) The evidence now available is discussed. While the implementation of SAFE programmes on the ground can be difficult, there is no doubt that every efforts should be made to pursue the strategy. Trachoma blindness is all the more tragic because it is so readily preventable.
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