Optimising Operational Use of Artemether-lumefantrine Comparing 3 Day Versus 5 Day

* The study will be conducted in 6 village health centres in the Mon and Kayin states * The patient or parent/guardian (in case of minor or under aged) must personally sign and date the latest approved version of the informed consent form before any study specific procedures are performed * A case record form will be completed for each patient documenting symptoms prior to clinic attendance, concomitant illness, drug history. Height, weight, vital signs and physical examination findings will be recorded. * At enrolment (D0) all patients will have the following samples taken: * Repeat parasite count (thick and thin films). Treatment should be started without waiting for the result. * Filter paper blood blots (3 dots on Whatman 3MM filter paper approx 180-300 µL blood) for parasite genotyping (MSP1, MSP2, GLURP in case of recurrence during follow-up) * Haemoglobin * Laboratory procedures * Slide microscopy: Thick and thin blood films stained with Giemsa will be read and counts expressed as the number of parasites per 500 white blood cells * Molecular studies: The samples will be used to detect asexual parasites (blood smear, sensitive PCR), parasite population structure (Sequenom genotyping and sequencing), gametocytes (microscopy). The samples will be stored in a cool box and kept maximum 5 days in the field and will be transported to the local laboratory for processing. Plasma and buffy coat will be separated, frozen and stored. The frozen packed red cells will be transported to the molecular laboratory at MORU, Bangkok, Thailand, for sample processing (DNA extraction, quantitative PCRs).