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Trachoma was not always so little known. It was once an exclusion criterion at Ellis Island for those wishing to immigrate into the United States (see photo). The sadness caused by such exclusions was memorialized in the autobiography of New York's Mayor LaGuardia, who had worked as an interpreter at Ellis Island.1 A "trachoma belt" was thought to exist in the United States as late as 1940.2 Trachoma hospitals were established in this belt, and the last of them did not close until the 1950s (around the time that C. trachomatis was finally cultured), when socioeconomic improvements had resulted in steadily decreasing trachoma rates in Europe and North America.
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The SAFE approach provides not only an effective public health intervention but also a rallying cry for implementing it. A single dose of azithromycin was found in many studies to be as effective as 6 weeks of treatment with topical tetracycline ointment.
In this issue of the Journal, Solomon et al. (pages 1870–1871) report heartening news from Tanzania: the remarkable effects of a single mass treatment with azithromycin in a small village and the complete absence of the organism 5 years after a second treatment. This report strengthens the view that trachoma as a cause of blindness need not persist beyond the first quarter of this century. Fifteen countries have launched national control efforts involving the SAFE guidelines and azithromycin. Although not all programs can report the dramatic decrease in infection rates seen in the Tanzanian village, national programs are no doubt partially responsible for a striking drop in worldwide rates — from approximately 100 million people infected in 1996 to 43 million in 2008, according to WHO estimates. Moreover, one does not have to eradicate the organism, nor eliminate every case of trachoma, to prevent blindness. Scarring and shortening of the upper eyelid in trachoma result from repeated infections. If prevalence falls to low levels (perhaps not even as low as those achieved in the Tanzanian village), trichiasis and blindness may not occur.
Although the SAFE strategy is effective, not all questions about how best to apply it have been answered. Operational research will be needed, and some relevant studies are under way or in the planning stages. The findings of Solomon et al. point to several immediate issues.
First, the evidence that a single mass treatment (or at most, two such treatments) may be sufficient in a low-prevalence area raises the question of whether the WHO should reconsider its recommendation that three annual treatments be administered in such areas. Second, there are questions about generalizability: for instance, it is unknown whether similar results can be expected in large areas, where mass treatment is unlikely to reach the 93 to 97% of the population treated in the Tanzanian village; and in areas where far more than 50% of children are infected — such as in Ethiopia — treatments may be required twice a year rather than once a year.
Third, the effectiveness of azithromycin may not be reflected in the commonly used clinical exams. Solomon et al. suggest that a point-of-care diagnostic assay is desirable; unfortunately, the one they cite has not yet been made available for further testing by other investigators.
Finally, mass treatment raises the specter of potential bacterial resistance. Ongoing monitoring is necessary; to date, studies in three countries have shown a return to pretreatment resistance levels of Streptococcus pneumoniae after mass treatment, but no resistance has been found for C. trachomatis.
The other elements of SAFE also require refinement or improved application. Surgery performed according to the WHO-recommended bilamellar tarsal-rotation procedure does halt corneal damage; however, trichiasis has been shown in several studies to recur in nearly 20% of patients. There is already evidence that quality control and retraining are needed to ensure that this 15-minute procedure (which is often performed by ophthalmologic nurses) meets quality standards. In addition, in areas of high transmission, standard azithromycin treatment at the time of surgery may improve results.
The facial-hygiene and environmental-change components of SAFE remain problematic and, with regard to improving sanitation and access to water, too expensive for some countries. The United Nations International Drinking Water Supply and Sanitation Decade, which ended in 1990, was not an unqualified success, largely because of the cost and complexity of the necessary interventions. Inventive approaches are being pursued to improve health education and change hygiene-related behavior through community participation. Manuals describing the application of the complete SAFE strategy are available from the WHO (www.who.int).
The WHO has been quite successful in defining the epidemiologic characteristics of blinding trachoma, continuing to encourage a small group of trachoma investigators, developing an effective public health strategy, convening an alliance, and organizing the means for defeating this disease. The gradual improvement in social conditions is clearly contributing to a decreasing prevalence, and Pfizer's donation of azithromycin may greatly hasten the elimination of blinding disease. Since 1998, approximately 74 million people have been treated. Among the 15 countries with national control programs, Morocco has already declared that trachoma has been eliminated. The WHO is now defining the criteria for certifying a country's elimination of trachoma.
Much work remains to be done, both to improve and to apply the SAFE strategy. Perhaps equally important, steps are being taken to integrate trachoma control with programs for controlling other "neglected" tropical diseases, especially schistosomiasis, lymphatic filariasis, onchocerciasis, and infection with soil-transmitted helminths.5 The early results achieved with the use of the SAFE strategy and azithromycin mass treatment suggest that elimination of blinding trachoma by 2020 is entirely possible.
No potential conflict of interest relevant to this article was reported.
Source Information
Dr. Cook is an adjunct professor of epidemiology at the School of Public Health, University of North Carolina, Chapel Hill.
A slide presentation is available with the full text of this article at www.nejm.org.
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Related Letters:
Two Doses of Azithromycin to Eliminate Trachoma in a Tanzanian Community
Solomon A. W., Harding-Esch E., Alexander N. D.E., Aguirre A., Holland M. J., Bailey R. L., Foster A., Mabey D. C.W., Massae P. A., Courtright P., Shao J. F.
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N Engl J Med 2008;
358:1870-1871, Apr 24, 2008.
Correspondence
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