Longitudinal evaluation of three azithromycin distribution strategies for treatment of trachoma in a sub-Saharan African country, Mali.

OBJECTIVES

Trachoma, caused by repeated ocular infections with Chlamydia trachomatis is an important cause of blindness. Mass azithromycin distribution is part of current recommended strategies for controlling trachoma. In order to ascertain an efficient strategy model at an acceptable cost, an intervention study was conducted in Mali between May 2000 and February 2002.

METHODS

Three azithromycin administration strategies were evaluated: mass community-based treatment of all residents (strategy I), treatment of all children under 11 years of age and of women between 15 and 50 (strategy II), and treatment targeted to inhabitants of households where at least one child had clinically active trachoma diagnosed (strategy III). In a particular Malian area in which trachoma was known to be mesoendemic, three villages were selected for each of the three strategies. According to the strategy allocation, adults were eventually given a single dose of 1g azithromycin, and children a unique dose of 20 mg/kg. Moreover, cleanliness and washing of children's faces were assessed, and additional questions were addressed about education, environmental and socio-economic conditions for each household at baseline. Ophthalmic examination was performed at baseline and 1, 6 and 12 months after inclusion. The outcome variable was clinically active trachoma frequency 12 months after intervention among children under 11 years of age. A descriptive analysis was performed, and then logistic regression models were built to test the efficiency of the three strategies.

RESULTS

Among children under 11 years of age, the active trachoma prevalence fell dramatically in each strategy, from 23.7% to 6.4% in strategy I, from 20.8% to 6.8% in strategy II, and from 20.2% to 8.5% in strategy III. After adjustment on age (adjusted odds ratio [AOR] = 0.81; 95% confidence interval [95% CI]: 0.75-0.87) and on active trachoma occurrence at baseline (AOR = 3.81; [95% CI]: 2.70-5.39), the multiple logistic regression model showed that both strategies I and II gave similar results, while strategy III appeared significantly less effective (AOR = 1.56; [95% CI]: 1.00-2.43).

CONCLUSION

In mesoendemic trachoma areas, targeted treatment to all children under 11 years of age and women between 15 and 50 (strategy II) was as effective as indiscriminate mass distribution (strategy I) and more effective than treatment targeted to inhabitants of households where at least one child had active trachoma diagnosed (strategy III). Strategy II could therefore reduce the prevalence and intensity of trachoma infection at a lower cost than mass community-based treatment of all residents (strategy I).