Jean-François Schémann

Active Trachoma among Children in Mali: Clustering and Environmental Risk Factors

Background Active trachoma is not uniformly distributed in endemic areas, and local environmental factors influencing its prevalence are not yet adequately understood. Determining whether clustering is a consistent phenomenon may help predict likely modes of transmission and help to determine the appropriate level at which to target control interventions. The aims of this study were, therefore, to disentangle the relative importance of clustering at different levels and to assess the respective role of individual, socio-demographic, and environmental factors on active trachoma prevalence among children in Mali. Methodology/Principal Findings We used anonymous data collected during the Mali national trachoma survey (1996–1997) at different levels of the traditional social structure (14,627 children under 10 years of age, 6,251 caretakers, 2,269 households, 203 villages). Besides field-collected data, environmental variables were retrieved later from various databases at the village level. Bayesian hierarchical logistic models were fit to these prevalence and exposure data. Clustering revealed significant results at four hierarchical levels. The higher proportion of the variation in the occurrence of active trachoma was attributable to the village level (36.7%), followed by household (25.3%), and child (24.7%) levels. Beyond some well-established individual risk factors (age between 3 and 5, dirty face, and flies on the face), we showed that caretaker-level (wiping after body washing), household-level (common ownership of radio, and motorbike), and village-level (presence of a womens association, average monthly maximal temperature and sunshine fraction, average annual mean temperature, presence of rainy days) features were associated with reduced active trachoma prevalence. Conclusions/Significance This study clearly indicates the importance of directing control efforts both at children with active trachoma as well as those with close contact, and at communities. The results support facial cleanliness and environmental improvements (the SAFE strategy) as population-health initiatives to combat blinding trachoma.

Prevalence of Undernutrition and Vitamin A Deficiency in the Dogon Region, Mali

Objectives: A representative sample of 1510 preschool children living in the Bandiagra circle (Mopti Region, Mali) was examined between March and April 1997 to determine the level of vitamin A deficiency. Methods: Using a randomized two level cluster sampling, 20 clusters of 75 children aged six months to six years were selected for evaluating xerophthalmia (XN night blindness and/or X1B Bitot spot). Concurrently stature and weight were determined. A semiquantitative seven-day dietary questionnaire was applied to the mothers of 484 infants to assess consumption of vitamin A rich foodstuffs. The prevalence of biochemical deficiency was attested using the Modified Relative Dose Response test (MRDR) on a sub-sample of 192. Results: Of the studied children, 4.3% (95% Confidence interval [CI]: 3.2–5.3) reported night blindness and 2% (95% CI: 1.3–2.7) had Bitot spots. Prevalence of xerophthalmia attested by at least one of these signs was 5.4% (95% CI: 4.2–6.5). The prevalence reached 10.5% at three years of age. The MRDR test proved abnormal in 77.1% of the subjects (95% CI: 70.3–82.7). Serum retinol was lower than 0.35 μmol/L in 43.8% (95.6% CI: 36.9–51.3) and less than 0.70 μmol/L in 92.7% of the children (95% CI: 87.8–95.8). Weekly consumption of vitamin A rich food was rare: 75.8% had not eaten any animal vitamin A rich food, and 22.1% had consumed less than seven times a vitamin A rich food of either vegetable or animal origin. Conclusions: These data define vitamin A deficiency as a severe public health problem in the Bandiagara area of Mali.

Trachoma and vitamin A deficiency.

Both vitamin A deficiency and trachoma are important causes of preventable ocular diseases. We examined 10 559 children in Mali for clinical signs of trachoma and of xerophthalmia. In five regions, the mean prevalence of trachoma was 39.3% (95% CI: 37.4-41.2). Clinical xerophthalmia was present among 1.89% of children (1.59-2.25). The diagnosis of xerophthalmia appeared to be associated with active trachoma (OR=2.04 [1.52-2.74]). This association remained after controlling for socio-economic status.

Mapping Xerophthalmia in Mali: Results of a National Survey on Regional Distribution and Related Risk Factors

Background: Vitamin A deficiency is recognized to be a severe public health problem in most of the sahelian countries. In Mali, several surveys had been performed at the district or regional level. Unfortunately, they did not cover the entire territory. In the aim of getting a general picture, we collected information on the frequency and presentation of xerophthalmia among the children under 10 years old population recruited in the setting of a national survey planned in 1996 and 1997 to evaluate the prevalence and determinants of trachoma in Mali. Methods: In each of the seven regions (with the exception of Bamako district), a random sample of thirty villages was taken from the general population. In a subsample of those villages, children under 10 years of age were examined by an ophthalmologist and their related mothers interviewed. Diagnosis of night blindness and Bitot spot occurrence was used for data gathering. Information was collected on villages infrastructures and familial socioeconomic condition. Multiple logistic regression analyses were performed to purpose the best model to describe the relationship between each outcome variable and the various risk factors assessed. Results: The prevalence of night blindness was estimated to be 1.95% (95% Confidence Interval [CI]: 1.58–2.39) and Bitot spots frequency to be 1.10% (95% CI: 0.83–1.45) among children between 2 and 6 years of age. Xerophthalmia prevalence was 2.51% (95% CI: 2.09–3.00) and nearly similar according to gender (2.68% among boys and 2.32% among girls). By region of the country and for the same age group, the prevalence ranged from 0.26% in the Kayes region to 7.02% in the Timbuktu region. In Mali, in four regions out of seven, the WHO thresholds defining a serious public health problem have been exceeded. The higher prevalence rates were found in Timbuktu, Mopti and Segou. After adjustment to season, the main risk factors were latitude, village size and poor sanitary coverage. The main protective determinants were education and rice culture. Conclusions: This presentation illustrates a public health problem concerning vitamin A deficiency among young children in the general population and allows considering the effectiveness of substitutive intervention with vitamin A capsule distribution along with the improvement of vitamin A rich food production and consumption.