Chloroquine-resistant Plasmodium falciparum malaria in Ilorin, Nigeria: prevalence and risk factors for treatment failure.

Presumptive treatment of fever with Chloroquine (CQ) remains the major strategy for malaria control in Nigeria. Efficacy surveillance of CQ must therefore be continuous for this strategy to remain valid. In this study we determined the efficacy of CQ in 120 patients aged 6m to 34yr who presented with acute uncomplicated Plasmodium falciparum malaria. Clinical success was 86.6%. Parasitological cure was 56.7%. Mean fever and parasite clearance times were 2.5 +/- 1.2D and 4.2 +/- 1.6D, respectively. Recrudescence rate was 24.45%. Twenty-four patients (20%) showed R11 response while 6 patients (5%) showed R111 response. Risk of treatment failure was significantly higher among children (< or = 15 yr) [P = 0.02, RR = 2.35 ] and among patients whose level of parasitaemia on day 2 was higher than day zero value. [P = 0.04; RR = 6.54]. Although malnutrition was not associated with higher risk of parasitological failure (P = 0.52), the proportion of children with R11/R111 response compared to R1 response was significantly higher among malnourished children compared to children with satisfactory nutritional status (OR 2.92; p = 0.001). The findings suggests the need for extra vigilance of CQ-Resistant P. falciparum (CRPF) malaria in children in general, and malnourished children in particular if potentially serious complications are to be averted.