The BLOOMy study is a longitudinal prospective cohort study of healthy children to assess the incidence of clinical malaria over the main transmission season. Participants will undergo baseline clinical and biological assessments then will receive a curative dose of either artesunate or dihydroartemisinin-piperaquine to clear any existing parasitemia. Clearance of parasites will be confirmed 3 weeks later by Polymerase chain reaction (PCR) and only participants with negative PCR will be definitively enrolled for the longitudinal follow up. Both active and passive case detection will be used to ensure that capture of a high proportion of infections in the cohort is achieved.

Blood samples for immunological assessments will be obtained at Day 0 of each positive blood smear episode before treatment and at Weeks 4 post treatment.

Participants will be followed for a minimum of six months throughout the malaria peak transmission season.

The BLOOMy study has two co-Primary objectives:

• To assess the incidence of clinical malaria meeting the primary case definition in children aged 1.5 to 12 years living in the study area over the main transmission season
• To assess the occurrence of reinfection following the radical cure of existing parasitemia.

The secondary objectives are:

• To assess the incidence of clinical malaria meeting various secondary cases definition in children aged 1.5 to 12 years living in the study area over the main transmission season
• To measure the immune responses (humoral and cell-mediated) to a panel of malaria vaccine candidate antigens
• To assess the molecular force of infection
• To pilot and standardize malaria morbidity assessment in three phase 2 malaria vaccine testing sites.

Inclusion Criteria:

• Healthy children aged 1.5 to 12 years
• Residence in the study area or surroundings for the period of the study
• Written informed consent from parents/legally acceptable representatives and an assent for children

Exclusion Criteria:

• Complicated symptomatic malaria (defined according to standard World Health Organization criteria)
• Anaemia (Hb<8g/dL),
• Any (chronic) illness that requires immediate clinical care.
• Family history of sudden death or of congenital or clinical conditions known to prolong QTcB or QTcF interval or e.g. family history of symptomatic cardiac arrhythmias, with clinically relevant bradycardia or severe cardiac disease
• Any treatment which can induce a lengthening of QT interval
• Known history of hypersensitivity or allergic reactions to piperaquine or other aminoquinolones
• Receipt of any blood transfusion or immunoglobulins within 3 months
• Known history of hypersensitivity or allergic reactions to artesunate
• Severe malnutrition (weight-for-height being below -3 standard deviation or less than 70% of median of the World Health Organization (WHO) normalized reference values).
• Weight below 5 kg
• Current or previous participation in malaria vaccine trials
• Current active participation in any trial involving administration of investigational drug.

Healthy children aged 1.5 to 12 years