[Effect of Onchocerca volvulus infestation on plasma vitamin A concentration in school children in a rural region of Cameroon]. / Influence de l'infestation par Onchocerca volvulus sur le taux sérique de vitamine A des enfants scolariss en zone rurale du Cameroun.

Vitamin A deficiency is known to be associated with immune dysfunction and common childhood infections. However, little is known about the relationship between vitamin A deficiency and onchocerciasis in children. The aim of this study was to determine the prevalence of vitamin A deficiency and to investigate the relationship between vitamin A status and onchocerciasis. A total of 231 children, aged 6 to 15 years, were randomly selected between March 1995 and April 1996 at Yambassa and Balamba (central province of Cameroon). They were examined: we determined their vitamin A status and whether they had onchocerciasis. We diagnosed onchocerciasis by skin biopsy and the detection of antibodies against Onchocerca volvulus in the blood. We found that 101 of the 231 children examined (43.73%) had palpable nodules and/or microfilariae and the remaining 130 (56.27%) had been exposed to the parasite but had no clinical signs of infestation. Some children tested negative for skin microfilariae but positive by ELISA. Thus, 197 (85.28%) children were found to be infested with O. volvulus (group A) and the remaining 34 (14.72%) were found to have been exposed to the parasite but to have no clinical signs of onchocerciasis (group B). Plasma vitamin A concentrations were marginal, with concentrations below 0.7 mumol/l (20 mug/dl) recorded for 82.25% of the subjects. Children with onchocerciasis were more likely to have low vitamin A status. The mean plasma vitamin A concentration of infested children (0.52 +/- 0.14 mumol/l) was significantly lower (p < 0.05) than that of the children exposed but not infested. The parasite, O. volvulus, uses the vitamin A present in host tissues during its development, leading to a decrease in plasma retinol concentration.

Vitamin A and E status of some rural populations in the north of Cameroon.

The vitamin A and E status was evaluated in 279 volunteer subjects, 3 to 75 years old (131 males and 148 females) from 8 villages in the north of Cameroon by fluorimetric methods. The results obtained showed that: the mean serum vitamin A level was 16.6 +/- 0.7 microgram % (ranging from 2.1 to 69.3 micrograms %) and vitamin E, 499.9 +/- 19.3 micrograms % (ranging from 222.7 to 1893.1 micrograms %); the percentage deficiency of vitamin A among the subjects was 71.7% and that of vitamin E was 66% (vitamin A levels < 20 micrograms/100 ml) vitamin E levels < 500 micrograms/100 ml; children of ages ranging from 3 to 15 years, constituted about 50% of the subjects and were significantly deficient in vitamin A (P < 0.001). Significant correlation was observed between the serum levels of vitamin A and E (P < 0.001). The results from this study revealed that vitamin A and E deficiencies vary from one village to another and constitute one of the major public health problems in the area.

PIP: Vitamin A is an essential micronutrient to growth and development and, vitamin E, as an antioxidant, plays an important role in vitamin A metabolism. To facilitate the design of food diversification and nutrition education campaigns, the vitamin A and E status of 279 children and adults, 3-75 years of age from 8 villages in North Cameroon, was assessed through fluorimetry. Mean serum levels of vitamins A and E were within normal limits in only 3 of the 8 villages. Overall, the mean serum vitamin A level was 16.6 +or- 0.7 mcg, and 71.7% of subjects were vitamin A-deficient. The mean serum vitamin E level was 499.9 +or- 19.3 mcg, and 66% were vitamin E-deficient. Serum levels of vitamins A and E were significantly correlated (p 0.001). Children 3-15 years of age had significantly lower levels of vitamin A than did adults (p 0.001). The severe vitamin A and E deficiencies recorded in this study reflect the dependence on cereals as a staple food in North Cameroon and the limited availability of palm oil, a daily source of beta-carotene in other regions of the country.