 In order to define the effectiveness of Intermittent Preventive Treatment in Infants IPTi with Sulfadoxine-Pyrimethamine, a novel principle of malaria intervention, the following parameters are evaluated: i the level of protection from malaria attacks and episodes of anemia during the treatment period, ii the level of protection from severe malaria during the treatment period, iii the effect on malaria morbidity after sustaining treatment, iv the decrease of overall morbidity and mortality, including the number of hospital admissions and visits of hospital outpatient departments v the influence of the intervention on the development of drug resistances, vi the impact of the intervention on the development of immunity, vii the possible influence of the intervention on sub-clinical organ dysfunction due to chronic Plasmodium falciparum infection. Parts of the study are performed in collaboration with the Laboratory of Research, Hospital Albert Schweitzer, Lambaréné, Gabon and the School of Medicine and Health Sciences, University of Development Studies, Tamale, Ghana 