Studies on Plasmodium falciparum parasitemia and development of anemia in Nigerian infants during their first year of life.

Bimonthly surveys were carried out for 12 months to investigate the dynamics of the acquisition of malaria parasitemia in relation to hemoglobin genotype, development of anemia, and body weight in infants during their first year of life. Thick blood smears for malaria, a capillary blood sample for measurement of packed cell volume (PCV) levels, and body weights were obtained at each survey. Generally, parasite rates (P < 0.001) and mean parasite densities (P < 0.025) increased with age. With a few exceptions, parasite rates and densities were similar in infants with hemoglobin AA and AS during the first year of life. Malaria parasitemia significantly lowered the PCV levels of the study infants only at four (P < 0.001), six (P < 0.025), eight (P < 0.001), and 10 (P < 0.01) months of age. No significant difference was observed in the mean body weight of malaria-positive and -negative infants during the first year of life except in infants two months of age (P < 0.05). The fairly rapid increase in parasite rate and density after two months of age is indicative of the decrease in protection after the first 2-3 months of life.