Sampling studies on the epidemiology and control of trachoma in southern Morocco.

Mass-treatment campaigns against trachoma and seasonal conjunctivitis, using chlortetracycline ointment, were started in 1952 in parts of southern Morocco. This paper reports the results of a survey carried out between 1962 and 1965, under the auspices of the Moroccan Government, WHO and UNICEF, to evaluate the effects of the mass-campaign.The survey assessed the prevalence, gravity and frequency of complications of trachoma by ophthalmological examinations, conducted in the home, and the results are compared with data published elsewhere which were obtained before treatment started in the 1950s in parts of the study area. Additional studies were made of the relation between trachoma and the availability and use of water, and between the prevalence of trachoma in females and their exposure to infection.The over-all prevalence of trachoma was unaffected by the mass-treatment campaign but a larger proportion of the cases were at stage IV of the disease (healed). In one region, however, the prevalence of active cases (stages I-III) in the younger age-groups had decreased considerably. The occurrence of pannus decreased and while trichiasis decreased in children under 15 years of age, its prevalence increased in adults. This result may be important in planning future mass-campaigns.