Changing the administration of the antibiotic azithromycin from once to twice a year in villages in Ethiopia substantially reduced eye infections in preschool children caused by chlamydia, which causes the serious, contagious eye disease trachoma, according to a study in the February 20 issue of JAMA: The Journal of the American Medical Association.
Trachoma is the leading infectious cause of blindness worldwide. Although it has been eliminated from Western Europe and the United States, it is still common in poor, arid areas such as rural sub-Saharan Africa. “The World Health Organization has launched a program to control trachoma, relying in large part on annual repeated mass azithromycin administrations. Program administrators anticipate that the treatments will reduce the prevalence of the ocular strains of chlamydia that cause trachoma to a level low enough that resulting blindness will be no longer be a major public health concern. However, local elimination of ocular chlamydia may be obtainable,” the authors write.
Elimination has become a particularly important goal because of a growing concern that infection may return into communities that have lost some of their immunity to chlamydia after antibiotics are discontinued. Mathematical models have suggested that elimination is possible, but may require relatively frequent treatments in regions with high incidence, according to background information in the article.
Muluken Melese, M.D., M.P.H., of Orbis International, Addis Ababa, Ethiopia, and colleagues compared the outcomes of azithromycin given annually and biannually to all residents (age 1 year or older) of 16 rural villages in the Gurage Zone, Ethiopia, an area with a high prevalence of trachoma, from March 2003 to April 2005. Overall, 14,897 of 16,403 eligible individuals (90.8 percent) received their scheduled treatment.
The researchers found that two annual treatments (at the beginning of the study and 12 months) reduced infection in preschool children in eight villages 6-fold, from 42.6 percent to 6.8 percent by 24 months. Four biannual treatments (baseline, 6, 12, and 18 months) reduced infection in preschool children in the other eight villages 35-fold, from 31.6 percent to 0.9 percent by 24 months. The prevalence of infection at 24 months was significantly lower in children in the biannually treated villages (0.9 percent) than in the annually treated villages (6.8 percent). At 24 months, no infection could be identified in preschool children in 6 of 8 of the residents receiving biannual treatment and 1 of 8 of the residents receiving annual treatments. Having no infection identified at 24 months was associated with being in the biannual treatment group.