Malaria prophylaxis is recommended for sickle cell disease patients. In Nigeria, daily proguanil or weekly pyrimethamine are the most commonly prescribed regimens, but the current policy is not effective due to poor compliance and drug resistance. Intermittent treatment with a long acting drug regimen administered under supervision at clinic visits may be more effective. The aim of this trial is to compare the tolerability and acceptability of supervised bimonthly treatment with either sulfadoxine-pyrimethamine plus amodiaquine (SP+AQ) or mefloquine plus artesunate (MQ+AS), with the daily proguanil. Two hundred and seventy patients with sickle cell disease attending the paediatric sickle cell disease clinic in Ilorin hospital who meet the eligibility criteria and have parental consent, will be randomized to one of three prophylactic regimens: daily proguanil, bimonthly sulfadoxine-pyrimethamine plus amodiaquine, or bimonthly mefloquine plus artesunate. Patients will be asked to return to clinic every two months and whenever they are sick. At enrollment, the study paediatrician will conduct a physical examination of the child, and collect a venous blood sample for a complete blood cell count and biochemical screen, determination of G6PD genotype, preparation of blood smears for malaria microscopy and a blood spot for determination of molecular markers of resistance. Four days after each clinic visit, patients will be interviewed (by phone and, for a subset, at home or in the clinic) to ask about compliance and adverse events. Participants will be followed for one year. The parents or carer will be encouraged to bring their child to the Outpatient Department clinic if the child becomes unwell. The primary outcome of the trial is tolerability, secondary outcomes are adherence to the regimen, and incidence of malaria and the number of hospitalizations over 12 months. If the bimonthly regimens are well tolerated and the preliminary data from this study are promising, a larger multicentre trial will be required to determine efficacy.

Inclusion Criteria:

• Age 6months or older and >=5kg
• Sickle cell clinic attendant
• Both males and females
• Agree to abide by the study protocol
• Give informed consent and assent
• Not acutely sick at the time of recruitment
• Not having additional chronic disease
• Hb genotype of SS and SC confirmed by electrophoresis

Exclusion Criteria:

• known allergy to any of the antimalarial drugs use in the trial,
• severe illnesses requiring urgent admission,
• treatment with sulfadoxine-pyrimethamine or mefloquine in the previous 2wks
• patients on cotrimoxazole prophylaxis