Trachoma in Northern Chad: Epidemiological survey

A regional survey was carried out in Chad in 2000 and 2001 to estimate the prevalence and severity of trachoma. The main objectives were to describe the epidemiological pattern in terms of prevalence of inflammatory trachoma and blinding complications in two sub-samples of the population: children under 10 years of age and women over 14. Two strata were identified based on geographical criteria: two regions [Ouaddaï-Biltine, North-East] and [Lac-Kanem-Chari Baguirmi, North-West]. Random samples of thirty clusters were selected in each stratum with probability proportional to size. The simplified grading system proposed by the World Health Organisation (WHO) was used. A total of 3,952 children and 2,492 women were examined. The participation in the survey was 95% for the children sample, 92% for the women sample and the representativity of the samples was fairly good. In children under 10 years of age, the prevalence of follicular trachoma (TF) was estimated at 31.5% (IC95%: 28.6-34.5) and that of intense inflammatory trachoma (TI) at 16.7% (IC95%: 14.4-19.2). The severity of the disease is high, as shown by the prevalence of trichiasis-entropion of 1.5% (IC95%: 0.9-2.2), of central corneal opacity of 1% (IC95%: 0.6-1.6) and of trachoma-related blindness of 0.5% (IC95%: 0.2-1) in women over 14. The epidemiological pattern of trachoma deserves particular attention in the field of public health in Northern Chad, where all indicators are consistently high. The national program for prevention of blindness has prepared a 3-year work plan to implement the SAFE strategy as soon as possible in these areas.