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March 19, 2003

Trachoma Leaves Millions Blind, Costs $2.9 Billion to Global Economy

School of Public Health Estimates Human and Monetary Burden of Trachoma

Researchers for the Johns Hopkins Bloomberg School of Public Health and the International Trachoma Initiative have calculated the human toll and economic burden of trachoma, a chronic infection that causes blindness. They estimate that there are 3.8 million cases of blindness and 5.3 million cases of low vision in countries known or suspected to have trachoma. In addition, they estimate $2.9 billion in lost productivity to low vision or blinding trachoma. The results appear in the article “Estimating the burden of trachomatous visual loss” in the April 2003 issue of Ophthalmic Epidemiology.

Kevin D. Frick, PhD, lead author of the study and associate professor in the Department of Health Policy and Management at the School, said, “Policy makers are interested in a variety of measures of the impact of this disease. Our article presents an updated, conservative estimate of the disability-adjusted life years attributable to trachomatous visual loss and presents the first dollar estimate--$2.9 billion per year. While this global total is small in comparison with the United States’ economy, this amount is greater than the GDP of some of the nations in which the disease is still present. In addition, this figure does not include the loss due to the pain and light sensitivity associated with complications of trachoma that precede visual loss.”

Worldwide attention to trachoma has suggested that it is a substantial global burden. Although calculations differ, all reports have found the number of people blinded from trachoma to be in the millions. The School researchers incorporated prior data, newly available data, and a list of countries that have been identified as having known or suspecting blinding trachoma since the last estimate of the global burden.

To estimate the prevalence and number of cases of trachomatous blindness and low vision, the researchers followed a previously used method of combining epidemiological data from multiple studies. As a reference point, the researchers defined blindness as corrected visual acuity in the better eye to be less than 3/60 and low vision as corrected visual acuity in the better eye to be less than 6/18, but better than or equal to 3/60. Visual acuity of 20/20 is considered normal. Visual loss was the combined categories of blindness and low vision. The researchers compared the burden of the disease with the expected costs of eradicating trachomatous blindness, to identify the dollar estimate for loss caused by this disease.

The researchers noted a lack of available high quality, published epidemiological data on trachomatous blindness and low vision as a barrier to future research. Dr. Frick said, “Future research should include a measure of the loss associated with all disability related to trachoma rather than focusing only on visual loss.”

M. Arantxa Colchero, MS, a research assistant in the School of Public Health’s Department of Health Policy and Management, and Christy L. Hanson, a graduate student in the Department of International Health, co-authored the study. Eva V. Basilion, MS, with the International Trachoma Initiative in New York, NY, was also a co-author.

The research was supported by grants from the International Trachoma Initiative.

Public Affairs Media Contacts for the Johns Hopkins Bloomberg School of Public Health: Kenna Brigham or Tim Parsons at 410-955-6878 or paffairs@jhsph.edu.