The effect of maternal, umbilical cord and placental malaria parasitaemia on the birthweight of newborns from South-western Cameroon.

AIM: The impact of maternal, umbilical cord and placental malaria parasitaemia on the incidence of low birthweight was investigated in pregnant women reporting for delivery at the Mutengene Maternity Centre, Fako Division, South West Province, Cameroon. METHODS: The malaria parasitaemia status of 770 umbilical cords, parturient women and placental impression smears were determined by light microscopy using blood samples collected between June 1999 and September 2001. The birthweights (BW) of the newborns were recorded soon after delivery. RESULTS: The results show that malaria parasites were present in the blood samples of 57 out of 730 (7.8%), 233/711 (32.8%) and 248/735 (33.7%) cord, maternal and placental biopsies respectively. Low birthweight (LBW) was recorded in 72 (9.6%) newborns, and the incidence was higher in primiparae. Newborns of mothers who had malaria parasites in their peripheral blood (12.4%) had a higher incidence (p=0.014) of LBW when compared with malaria parasite-free mothers (6.8%). Similarly, neonates born from malaria-positive placentas (13.5%) had a significantly higher incidence of LBW (p=0.006) than those from parasite-negative placentas (6.8%). Furthermore, newborns of malaria parasite-positive mothers, umbilical cords, placentas and primiparae had lower mean birthweight than malaria-negative mothers, placentas, umbilical cords and multiparae. CONCLUSION: We suggest that parity and maternal and placental malaria parasitaemia at delivery have an important negative impact on birthweight, especially in first pregnancies. This observation emphasizes the need for appropriate aggressive intervention strategies such as the use of insecticide-treated bed nets or intermittent preventive treatment to control malaria in pregnancy in the study area.

Studies on Plasmodium falciparum isotypic antibodies and numbers of IL-4 and IFN-gamma secreting cells in paired maternal cord blood from South West Cameroon.

OBJECTIVES: In this study, the effect of maternal peripheral and placental Plasmodium falciparum parasitaemia on the level of antibody and cytokine immune responses in the neonate was investigated. METHODS: Malaria parasites were detected by light microscopy. Levels of malaria-specific isotypic antibodies were measured in maternal and cord blood by indirect ELISA. The numbers of IFN-gamma and IL-4 cells produced by maternal/cord blood after in vitro stimulation were enumerated using the ELISPOT assay. RESULTS: Malaria parasite rate of maternal, placental biopsy and cord blood was 32.8%, 33.7% and 7.8% respectively. Overall, ELISA seropositivity rates for P. falciparum-specific IgG, IgM, IgE and IgA in the maternal plasma samples were 71%, 85%, 29.3%, and 0% respectively, while those for the cord samples were 69%, 6.0%, 4.4% and 0% respectively. Mean IgM ELISA OD(405) values of neonates born from positive placentas, or whose mothers had peripheral malaria parasitaemia were higher than those who were parasite negative. The mean number of maternal cells producing IFN-gamma was higher (P=0.0001) than that of the paired cord samples. The mean number of IL-4 producing cells of neonates born of mothers who were positive (P<0.05) or from malaria-positive placentas (P<0.025) was higher than from those who were malaria negative. Neonates born of malaria-positive mothers or from parasitized placentas mounted predominantly Th2 type immune responses. CONCLUSION: It appears from this study that neonates born from malaria-infected mothers or placentas may relatively be more susceptible to malaria attack during the first years of life.

Plasmodium falciparum inhibitory capacities of paired maternal-cord sera from south-west province, Cameroon.

In malaria endemic areas, young children are protected against malaria attack during the first few weeks of life partially by transplacentally acquired antibodies. In this study, we show, using an in vitro assay, that part of these antibodies are involved with blocking the re-invasion of host red blood cells by erythrocytic merozoites. One hundred consecutive paired maternal-cord blood samples were collected at delivery and their plasma assayed for total IgG antibodies against crude blood stage antigens by the ELISA. The Ig fraction were precipitated from the plasma samples with (NH(4))(2)SO(4), purified on PD10 columns and used in vitro in determining the re-invasion inhibitory capacities. The mean (+/-SD) ELISA OD(405) IgG antibodies to crude blood stage antigens of maternal (0.476 +/- 0.48) and cord (0.421 +/- 0.39) plasma samples was not significantly different. However, the mean total protein concentration of the Ig fractions for maternal samples (15.82 +/- 3.85) was significantly higher (p=0.005) than that of paired cord samples (12.87 +/- 2.86 mg/ml). There was no correlation between anti-Plasmodium falciparum-specific IgG levels and total protein concentrations of the Ig fractions of both maternal and cord samples. The entire test Ig fractions were strongly inhibitory (>50 per cent) except for four paired maternal cord samples, which were moderately inhibitory (21--50 per cent) at the highest concentration tested (1:2 dilution). Furthermore, there was no correlation between maternal IgG levels and percentage re-invasion inhibition at the 1:2 dilution. The results suggest that mothers resident in malaria endemic areas possess naturally acquired re-invasion inhibitory antibodies and their foetuses can acquire these antibodies transplacentally, which may contribute to the relative protection observed in infants during their first few weeks of life.