In areas endemic for malaria, pregnant women frequently present with a placenta that has been parasitized by Plasmodium falciparum, an infection associated with a reduction in the birth weight of the offspring. However, the impact of placental infection on malaria-related morbidity during the infant's first years of life has not been investigated. Between 1993 and 1995, 197 children in southern Cameroon were followed weekly clinically and monthly parasitologically. The dates of first positive blood smear and the evolution of the parasite prevalence rates were compared between infants born to mothers presenting with (n = 42) and without (n = 155) P. falciparum infection of the placenta. Infants born to placenta-infected mothers were more likely to develop a malaria infection between 4 and 6 months of age; then the difference progressively disappeared. Similarly, parasite prevalence rates were higher in placenta-infected infants from 5 to 8 months of age. Thus, malarial infection of the placenta seems to result in a higher susceptibility of infants to the parasite. This was not related to maternally transmitted antibodies, as specific antibody levels were similar in both groups of infants. A better understanding of the involved mechanisms may have important implications for the development of malaria control strategies.
PIP: Parasitization of the placenta with Plasmodium falciparum is not uncommon in pregnant women in areas endemic for malaria and has been associated with low birth weight. To assess the impact of placental infection on malaria-related morbidity during the first 2 years of life, 197 children from southern Cameroon were followed weekly clinically and monthly parasitologically in 1993-95. 42 infants (21.3) had mothers with P. falciparum placental infection. Umbilical cord blood levels of total and specific anti-P. falciparum immunoglobulin were similar in both groups of infants. Infants born to placenta-infected mothers were significantly more likely to develop malaria at 4-6 months of age--but not in subsequent months--than those born to non-placenta-infected mothers. Similarly, parasite prevalence rates were higher in placenta-infected infants from 5-8 months of age. 46.5% of children in the placenta-infected mother group and 38.5% of those in the non-placenta-infected mother group had at least one malaria attack during the study period. These findings indicate that infants of mothers presenting with P. falciparum infection of the placenta are more susceptible to malaria infection in the first 2 years of life. Improved understanding of the mechanisms underlying immune responses to P. falciparum in newborns and infants is needed to guide the development of malaria control strategies.