High reinfection rate and treatment failures in children treated with amodiaquine for falciparum malaria in Muheza villages, Northeastern Tanzania

In May 2003, we studied amodiaquine (AQ) efficacy in children5 years of age with uncomplicated falciparum malaria in Magoda and Mpapayu (with insecticide treated nets [ITNs]) and Mgome (without ITNs) in Muheza, Tanzania. The trial involved 28 days of follow-up, and data were adjusted by polymerase chain reaction (PCR) genotyping of msp1 and msp2 genes. Additionally, Pfcrt codon 72-76 polymorphisms were studied by PCR and sequence-specific oligonucleotide probe (SSOP) ELISA. In 54 cases with complete follow-up, a significant difference in late treatment failure (LTF) rates was seen (60.7% in ITN versus 88.5% in non-ITN villages, P = 0.02) before PCR correction. However, after PCR correction, 23 cases (60.5%) were confirmed as reinfections, giving a true LTF rate of 21.4% (6/28) and 34.6% (9/26) in the above settings, respectively. Frequency of Pfcrt CVIET haplotype mutation pretreatment was high (97.0%); the remaining samples were CVMNK. We conclude that AQ alone is no longer effective in the study area.