Anti-malarial drug resistance, malnutrition and socio-economic status.

To investigate the relationship between nutritional status and resistance to chloroquine treatment, we designed a nested case-control study prospective with respective to the outcome of Plasmodium falciparum-infected school children aged 5-14 years from Honiara, Solomon Islands. 38 chloroquine-resistant cases were compared with treatment-susceptible controls with respect to current nutritional status, behavioural characteristics, medical and demographic data. The overall prevalence of moderate malnutrition was 28%. The incidence rate of chloroquine resistance was 23%. Malnourished children were generally at higher risk for treatment failure than well-nourished ones (OR: 3.6; 95% CI: 1.6-8.4; P = 0.001). This effect was modified by socio-economic status. Stratified analysis by logistic regression resulted in an eightfold risk of resistance for malnourished children in the higher socio-economic category (OR: 8.1; 95% CI: 2.4-27.9; P = -.0001). In children from the lower socio-economic group, the effect of malnutrition was not significant (OR: 1.5; 95% CI: 0.4-5.6). Socio-economic differences may affect the immune status. The treatment response in children of lower socio-economic status, which are more exposed to malaria, may therefore be less affected by malnutrition.