The Noguchi Memorial Institute for Medical Research together with the Navrongo Health Research Centre have recruited malaria cases and healthy controls to contribute to Consortial Project 1These individuals were collected from the Kassena-Nankana District of the Upper East region of Ghana. The major ethnic groups in the study area are the Kassem and Nankani. Annual rainfall averages to about 850-950mm and occurs predominately in the months of June-October which corresponds with the high malaria transmission season. The main malaria vectors are Anopheles gambiae s.l and A. funestus, constituting about 94.3% of the vector population. The overall annual entomological inoculation rate has been estimated to be around 400.

Description of study population - Cases

Cases consist of children (5 months-5 years) with signs of severe or uncomplicated malaria. Severe malaria cases were recruited between 2002-04 and 2007-08 from the paediatric ward of the Navrongo War Memorial Hospital. Uncomplicated malaria cases were recruited from the out-patient department of the same hospital and three health centers. Recruitment of uncomplicated malaria cases was done within 5 days of enrolling a severe malaria case, with 2 uncomplicated cases selected per case. They were frequency matched to severe cases by age, sex, location and ethnicity.

Severe malaria was defined by the presence of asexual parasitemia and at least one of the following: cerebral malaria (Blantyre coma score of 3 or below and coma persists for more than 30 minutes after fits have ceased); repeated or prolonged generalized convulsions; severe malarial anemia (hemoglobin<5g/dl); respiratory distress; hypoglycaemia (blood glucose <2.2mM/L); circulatory collapse (systolic blood pressure<50mmHg); renal failure (urine output less than 12ml/Kg/24 hours or serum creatine >3.0mg/dL); hyperpyrexia (rectal temperature >39 0C and impaired consciousness).

Description of study population - Controls

Controls consist of apparently healthy children (0-5 years), selected from the Navrongo demographic surveillance system, which keeps vital records of the 150,000 residents of the Kassena-Nankana District. Controls were frequency matched by age, gender, location and ethnicity to severe malaria cases prior to 2007, after which they were individually matched to severe malaria cases using the same criteria.