Children enrolled in the study were seen at the OPD clinic at the end of malaria transmission season for examination by a study physician and a finger-prick blood sample was obtained for preparation of thick blood smear and determination of haematocrit. A standardized questionnaire was administered to the parents/guardians of the study subject, to collect information regarding illness that had occurred since the last visit, symptoms experienced, use of healthcare facilities and use of medicines. Information on the use of bednets was collected again at this visit.