MALARIA INFECTION IN INFANCY IN RURAL MALAWI

Malaria infection is thought to be relatively infrequent in infants le ss than 90 days of age in sub-Saharan Africa. In a rural area of Malaw i with intense malaria transmission, we examined the occurrence of mal aria infection during infancy and risk factors for parasitemia in the first three months of life in the cohort of infants delivered to women in the Mangochi Malaria Research Project. Among 3,915 liveborn single ton infants, 3,432 (87.7%) were seen at least once during infancy (fir st 12 months of life); of these, malaria blood smear results were avai lable on 2,649 (77.2%). Overall, in a cross-sectional analysis, 23.3% of infants at three months of age were infected with Plasmodium falcip arum; this proportion increased to more than 30% during the high trans mission season. By the age of 10 months, 60-80% of the infants were in fected, depending on the season. Geometric mean parasite density incre ased each month after two months of age and plateaued at seven months of age. In a life-table analysis, the median time to acquisition of a positive smear was 199 days. Factors independently associated with sme ar positivity at < 4 months of age included visit during high transmis sion season (adjusted odds ratio [AOR] = 4.1), maternal smear positivi ty at the same visit (AOR = 3.5), history of infant fever in the previ ous two weeks (AOR = 2.8), birth during the rainy season (AOR = 1.7), low socioeconomic status (AOR = 1.6), and low maternal education (AOR = 1.5). The specificity of a recent fever history for malaria infectio n in early infancy was high (> 70%). Intervention strategies to reduce the risk of early infant infection need to be targeted toward mothers of infants at high risk.