A longitudinal study on immune responses in relation to protection against clinical malaria episodes will be conducted in Apac District, Uganda. Three cohorts will be recruited: children 1 to 5 years of age (n=250), children 6 to 10 years of age (n=125) and adults 25 and above (n=125). After finger prick sampling (~300µL) and examination at enrolment, participants will be followed up for one year. Follow-up will include fortnightly active case detection and three-monthly cross-sectional surveys. Clinical malaria attacks and the associated clinical and parasitological parameters will be related to immunological profiles determined utilizing a protein microarray as a capture substratum to profile the humoral immune response against a vast number of parasite antigens.

For individuals who experience a clinical malaria attack or who are diagnosed with high density parasitaemia (≥15,000 parasites/µL) during cross-sectional surveys, a 5mL blood sample is obtained to determine the diversity of parasite antigens in the population in relation to antigen recognition in the cohort.

Inclusion Criteria:

• age 1-5 years, 6-10 years or 25 yearsand above
• written informed consent must be given
• the individual must have been resident of the area since birth or for a minimum period of two years
• the individual must be willing to submit required information and to participate in repeated sampling (total blood volume ~2.5 mL over a period of 12 months)
• Absence of danger signs (as defined by WHO) or clinical features of AIDS. An HIV-test will be offered to all participants at enrolment and completion of the study.

Exclusion Criteria:

• unwillingness to sign consent form
• unwillingness to reside in the study area during the follow-up period

Randomly selected individuals living in Abedi, Apac District, Uganda.