The genotyping will be performed at the department of Medical Microbiology, at the Academic Medical Center (Amsterdam, The Netherlands), under the supervision of Prof. Dr Tom van Gool. A material transfer agreement will be signed. The genotyping procedure will be based on comparison of the two-locus genotype resulting from expression of the P. falciparum MSP-1 and MSP-2 gene alleles in pre- (enrolment) and post-treatment (failure) samples27. Pre- and post-treatment pairs with similar genotype will be classified as recrudescence (true failure), and pairs with different genotype will be classified as re-infection.