Malaria during pregnancy can result in low birth weight (LBW), an important risk factor for infant mortality. This article reviews the pathological effects of malaria during pregnancy and the implications for the newborn's development and survival. Empirical data from throughout Africa on associations between placental malaria and birth weight outcome, birth weight outcome and infant mortality, and the rates of LBW in areas with various levels of malaria transmission are evaluated to assess the increased risks of LBW and infant mortality associated with malaria. It is estimated that in areas where malaria is endemic, around 19% of infant LBWs are due to malaria and 6% of infant deaths are due to LBW caused by malaria. These estimates imply that around 100,000 infant deaths each year could be due to LBW caused by malaria during pregnancy in areas of malaria endemicity in Africa.

Abstract. The paucity of precise information on the burden of malaria among pregnant women has hampered effective lobbying for the inclusion of preventative strategies against malaria in Safe Motherhood Initiatives. This article reviews the evidence on the coincidental risks of malaria and anemia in Africa and attempts to estimate the probable burden of malaria-related severe anemia in this susceptible group. Twenty-six studies on hemoglobin levels in all-parity pregnant women throughout this region could be matched with a malaria parasite ratio in children Ͻ 15 yr old (a measure of the intensity of transmission). In areas with no malaria, the mean hemoglobin levels were markedly higher than those found in areas with stable malaria transmission, though changes with increasing intensity of transmission were unclear. Eighteen studies from areas with stable malaria transmission in sub-Saharan Africa suggested that the median prevalence of severe anemia in all-parity pregnant women is approximately 8.2%. Assuming that 26% of these cases are due to malaria, it is suggested that as many as 400,000 pregnant women may have developed severe anemia as a result of infection with malaria in sub-Saharan Africa in 1995.

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Intestinal nematode infections are recognized as a major public health problem, and helminth control is currently being directed towards school-aged children who are known to harbour the heaviest infections and are most likely to suffer from associated morbidity. However, few data are available for the epidemiology of intestinal nematodes in pre-school children in Africa, and the contribution of hookworm infection to the aetiology and severity of anaemia among pre-school children remains poorly understood. This paper investigates the epidemiology of parasitic infections in 460 pre-school children who were part of a larger case-control study of severe malaria in Kilifi on the Kenyan coast. Almost one-third (28.7%) were infected with hookworm, 20.2% with Ascaris lumbricoides and 15.0% with Trichuris trichiura. Infection prevalence of each species rose with age, and the prevalence of heavy infection with hookworm and mean intensity of hookworm were markedly age-dependent. One-third (34.3%) of children had malaria. Overall, 76.3% of children were anaemic (haemoglobin < 110 g/L), with the prevalence decreasing with age. Anaemia was significantly worst in children with heavy hookworm infection (> 200 eggs per gram). This relationship held for all ages, both sexes, and was independent of socioeconomic factors. The application of attributable morbidity methods confirmed the contribution of hookworm infection to anaemia.

A cross-sectional study of 6897 schoolchildren in 59 out of the 155 primary schools in Magu District on the shores of Lake Victoria, Tanzania, was undertaken in 1997 to determine the prevalence of single- and multiple-species helminth infection. Schistosoma haematobium, hookworm (primarily Necator americanus) and S. mansoni were the most common helminth species infecting schoolchildren in the district. The prevalences of Ascaris lumbricoides and Trichuris trichiura were negligible (< 1%). Anaemia and stunting were highly prevalent and widespread. Hookworm and S. mansoni occurred more frequently in multiple infections with other helminths than as single-species infections, but triple-species infection was rare. Analysis of the frequency distribution of infection amongst schools showed that prevalences of S. haematobium and hookworm tended to be normally distributed, with medians 75% and 45%, respectively, while the distribution of S. mansoni was markedly skewed such that only 17% schools had a prevalence greater than 20%. An inverse association between S. mansoni and S. haematobium was observed. Geographical information system (GIS) analysis indicated that S. mansoni infection was highly prevalent only along the shore of Lake Victoria, whilst S. haematobium was homogeneously prevalent everywhere except the lakeshore. This pattern appears to reflect the distribution of schistosome species-specific snail intermediate hosts. The results imply that joint treatment for hookworm infection and schistosomiasis would be beneficial throughout the district.

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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.

These findings document effects of early childhood diarrhea on later school readiness and performance and hence potential long-term human and economic costs of ECD, which warrant further attention and far greater investment for the control of ECD and its consequences.