https://www.thelancet.com/pdfs/journals/lancet/PIIS0140-6736(97)02038-2.pdf

Relation between severe malaria morbidity in children and level of Plasmodium falciparum transmission in Africa

The incidence of placental malaria at parturition and its effects on the conceptus have been investigated in The Gambia, West Africa. Malarious placentae occurred in 1300 (20.2%) of 6427 singleton births, in 32 (18.6%) of 172 sets of twins and in none of six sets of triplets. Plasmodium falciparum infections predominated; P. malariae or P. ovale infections were found in only nine instances. In the large group of single births placental malaria occurred less frequently (12.0%) in residents of urban than of other, more rural, communities (27.1%). In the former group incidence showed no clear change with season; in the latter group it was highest in the trimester following the end of the rains and lowest in the second half of the dry season. In both residential groups it was more frequent in primiparae (urban 16.1%; other 46.9%) than in multiparae (urban 8.9%; other 20.3%). The sex of the child did not influence malaria incidence. Dense placental infections were more frequent in primiparae. Stillbirth rates of singleton infants were significantly higher for males than for females, but no clear and consistent relationship between stillbirth and placental malaria was detected. Mean singleton birthweights were depressed by about 170 g in the presence of malaria; the deficits were statistically significant only among first born infants and tended to diminish progressively with increasing maternal parity. No distinct gradient linking birthweight with ascending density of placental parasitaemia was observed. Singleton birthweights of 2.5 kg or less occurred more frequently in association with malarious than non-malarious placentae and the association was more marked among first born than later birth rank infants. Differences between the weights of malarious and non-malarious placentae were small and not significant. The findings of the study are discussed in relation to the widely prevalent view that pregnancy exacerbates maternal malaria by attenuating acquired immunity.

Malaria infection of the placenta in The Gambia, West Africa; its incidence and relationship to stillbirth, birthweight and placental weight

https://www.cell.com/parasitology/pdf/0169-4758(95)80151-0.pdf

Malaria during pregnancy: A priority area of malaria research and control

Although randomized controlled trials of interventions to reduce malaria in pregnancy have demonstrated an increase in the birthweight of the newborn in primigravidae, the subsequent impact on infant mortality in all-parities has not been assessed. The aim of this paper was to model the possible impact of placental malarial infection on infant mortality through reduced birthweight. An extensive literature search was undertaken to define a series of parameters describing the associations between placental infection, birthweight and premature mortality in sub-Saharan Africa. It was shown that a baby is twice as likely to be born of low birthweight if the mother has an infected placenta at the time of delivery (all-parities: 23% vs 11%, primigravidae only: 32% vs 16%), and that the probability of premature mortality of African newborns in the first year of life is 3 times higher in babies of low birthweight than in those of normal birthweight (16% vs 4.6%). Assuming 25% of pregnant women in malaria-endemic areas of Africa harbour placental malarial infection, it is suggested that 5.7% of infant deaths in malarious areas could be an indirect cause of malaria in pregnancy. This would imply that, in 1997, malaria in pregnancy could have been responsible for around 3700 infant deaths under the diverse epidemiological conditions in Kenya. Placental infection with Plasmodium falciparum appears to have a more significant role in infant survival in Africa than has been previously assumed. This may explain the high reduction in infant mortality rates from interventions aimed at reducing transmission, over and above that expected from a decline in direct malaria-specific mortality alone.

Malaria in pregnancy as an indirect cause of infant mortality in sub-Saharan Africa.

Effect of infection on food intake and the nutritional state: perspectives as viewed from the village.

IgG, IgA, IgM and IgD concentrations in plasma were measured at three surveys of a rural Gambian community made over 13 months. 3523 samples were analysed. The pattern of change with age of mean levels of each immunoglobulin class was similar at each survey, although IgM levels were highest in the survey made at the end of the wet season. Immunoglobulin levels in the same individual were found to be relatively stable in adults over the study period. Only minor correlations were found between the levels of different immunoglobulin classes in plasma from the same individual.

Malarial parasitaemia was associated with increased mean IgG levels in age groups up to 20 years but with increased IgM levels only in the first 2 years of life. Plasma which contained precipitating antibodies to malarial antigens showed higher mean levels of IgG and IgM in most age groups. In association with splenomegaly mean IgG levels were increased throughout childhood while mean IgM levels were elevated only in the first 2 years. No consistent relationship between malaria and mean levels of IgA and IgD were noted. The only relationship found between haemoglobin concentration and immunoglobulin levels was a small negative correlation in respect of IgM.

Clinical infection, other than malaria, was associated with increased mean levels of IgG and IgA in all age groups and of IgM in young children. Lower levels of IgG, IgA and IgM occurred in pregnancy; IgG levels seemed to fall progressively as pregnancy advanced. At certain ages mean levels of IgM and IgD were higher in females than males.

Plasma immunoglobulin concentrations in an African (Gambian) community in relation to season, malaria and other infections and pregnancy.

The immunoglobulin levels in sera from mothers and newborn infants were studied in Gambian, Nigerian, and Swiss populations. The maternal levels of IgG and IgM, but not IgA, varied with locality. As they were highest in Gambian and lowest in Swiss women, they may have reflected differences in the endemicity of infectious diseases in the different environments. The neonatal Ig levels showed less variation than the maternal. Neither maternal nor neonatal levels of IgG showed any consistent relationship with birthweight; however, when maternal IgG levels were low the neonatal levels tended to exceed them. The mean IgG and IgM levels were higher in Gambian than in Nigerian or Swiss infants; the higher IgM values may have been due to more frequent antigenic stimulation in utero in the Gambian group. Evidence of placental malaria, mainly falciparum, was found in 76 of 234 Gambian women. No parasites were found in the blood from any neonate. The maternal levels of IgG, but not of IgM or IgA, were significantly elevated in association with placental malaria. The neonatal immunoglobulin levels were not influenced by placental malaria and no evidence was found to indicate that malaria infection of the placenta induced an immune response in the fetus.

Plasma immunoglobulin concentrations in mothers and newborn children with special reference to placental malaria: Studies in the Gambia, Nigeria, and Switzerland.

D S Rowe

Papers

Plasma immunoglobulin concentrations in an African (Gambian) community in relation to season, malaria and other infections and pregnancy.

Plasma immunoglobulin concentrations in mothers and newborn children with special reference to placental malaria: Studies in the Gambia, Nigeria, and Switzerland.

Family studies in immunoglobulin levels.