Serum concentration of micronutrients in relation to schistosomiasis and indicators of infection: a cross-sectional study among rural Zimbabwean schoolchildren.

OBJECTIVE

To study the relation between indicators of infection and Schistosoma mansoni and S. haematobium infection, and serum concentrations of zinc, ferritin and retinol.

DESIGN

Cross-sectional.

SETTING AND SUBJECTS

313 rural Zimbabwean schoolchildren (144 boys and 169 girls, 11-17 years).

VARIABLES

S. mansoni and S. haematobium egg output, concentration of C-reactive protein, neutrophil count, questionnaire data on fever and diarrhoea, and serum concentrations of retinol, ferritin and zinc.

RESULTS

Age, elevated CRP, fever and S. mansoni egg output were significant predictors of the concentration of retinol. The regression coefficient for age was positive, and negative for elevated CRP, fever and S. mansoni egg output. As S. mansoni, but not S. haematobium, was of significance, it is unlikely that low retinol level increased susceptibility to infection. The effect of S. mansoni on retinol level was 0.03 mumol/l (95% CI: 0.002-0.06, P = 0.03) for each 100 eggs/g increase in egg output. Neither indicators of infection nor age and sex were predictors of concentration of zinc and log10 concentration of ferritin.

CONCLUSION

S. mansoni infection reduced retinol level, when indicators of infection and age were controlled for. High intensities of S. mansoni infection may induce vitamin A deficiency among children with marginal vitamin A status. The study emphasizes the importance of controlling for age and metabolic response to concurrent infections in studies using serum retinol as a measure of vitamin A status.