Papers for this Review were identified by searches of PubMed with the search terms “malaria” AND [“pregnancy” OR “pregnant”] AND [“burden” OR “prevalence”] to January, 2006. Additional references were obtained from references of the articles in the search, and from malaria in pregnancy databases of published and unpublished literature at CDC and Liverpool School of Tropical Medicine. Special consideration was given to articles identified as reviews in PubMed. Only papers published in
ReviewEpidemiology and burden of malaria in pregnancy
Introduction
“So long as Woman has walked the earth, malaria may have stalked her”;1 however, the problem of malaria in pregnancy was not described until the early 20th century.2, 3 This was followed by almost four decades of descriptive studies in sub-Saharan Africa that focused on the frequency of Plasmodium falciparum placental infection and its adverse effects.4, 5, 6, 7, 8, 9 In the past two decades, many comprehensive reviews have highlighted various aspects of malaria in pregnancy and its effect on maternal, newborn, and infant health. In this review, we compile these estimates across the spectrum of disease manifestations, including what is known in low and unstable transmission areas within and outside of sub-Saharan Africa and of species other than P falciparum. We used data from review articles, and included new data that were recently published if it provided important new information or insights.
Our aim is to identify gaps in knowledge of the epidemiology and burden of malaria in pregnancy globally, and to chart a course for gathering requisite knowledge to fill those gaps both through special studies and routine data-gathering exercises such as monitoring, surveillance, and evaluation.
Section snippets
Stable transmission in Africa
A myriad of studies have reported on the prevalence of peripheral and placental parasitaemia in areas of stable endemic malaria transmission in Africa. Data from Africa before 1980 have been summarised in a review by Brabin and colleagues.10 In another review of 20 studies from eight countries in Africa done between 1985 and 2000, the median prevalence of maternal malaria infection (defined as peripheral or placental infection) in all gravidae was 27·8%.11 A similar estimate of 26% was obtained
Effects on maternal health
The clinical features of malaria infection during pregnancy vary by the degree of immunity that women have acquired by the time they become pregnant, and thus by the epidemiological setting (figure 1).
Stable transmission in Africa
Malaria in pregnancy has an unequivocally devastating effect on the newborn infant (table 4). Low birthweight (defined as birthweight <2500 g) is associated with a marked increase in infant mortality.11, 30, 50, 52, 53 In areas of high malaria transmission in Africa, the risk of low birthweight approximately doubles if women have placental malaria,12 with the greatest effect in primigravidae.54 The odds ratio of low birthweight associated with malaria is two to seven times higher in primigravid
Effect on infant outcomes
The prevalence of fetal anaemia at birth is high in malaria-endemic areas, and the risk is associated with the presence of high-density parasitaemia in the mother at delivery.61 Few studies report the effect of malaria in the pregnant mother on anaemia or malaria in the infant (Table 5, Table 6). Some studies have now shown that the risk of all-cause anaemia is estimated to be three times higher among infants born to mothers with placental parasitaemia, even after adjusting for environmental
Long-term consequences for the child
There is a dearth of literature on the long-term consequences of malaria in pregnancy for the child. A large number of mainly nutritional studies indicate that exposure to an abnormal intrauterine environment affects mental, metabolic, and anthropometric development, resulting in increased risk of disease later in life. In high-income countries, low birthweight has been associated with higher arterial pressure, chronic kidney disease, ischaemic cardiomyopathy, stroke, diabetes, respiratory
Interaction with HIV
The burden of malaria in pregnancy is exacerbated by co-infection with HIV. Sub-Saharan Africa bears the brunt of this comorbidity, where approximately 25 million pregnant women are at risk of P falciparum infection every year,11, 100 and 77% (13·5 million) of the world's HIV-infected women reside.101 A review of 11 studies from Africa highlights the deleterious effect of HIV on malaria, reporting higher risks of placental malaria (summary relative risk 1·66, 95% CI 1·48–1·87), high-density
Effect of other Plasmodium species
Although all four Plasmodium species can infect pregnant women, only susceptibility to P vivax and P falciparum has been studied.102, 103 Most of the data on P vivax infections are from regions outside Africa. Women are at increased risk of P vivax infection during pregnancy, although the increased risk is less pronounced than with P falciparum; data from Brazil show that the ratio of P falciparum to P vivax was 1:5·6 in a group of non-pregnant infected women, whereas it was only half that
Estimating burden
Any attempt to quantify the global burden of malaria in pregnancy is made more difficult by a lack of an accurate and good quality estimation of both the numerator (ie, women affected by adverse outcomes of malaria in pregnancy) and the denominator (ie, the population at risk). The numbers of women at risk of malaria in pregnancy are underestimated because of the practice of using routine national reporting systems, especially outside Africa, and because the number of unidentified pregnancies
Gaps in public-health knowledge
On the basis of the above review, it is clear that the clinical consequences of malaria in pregnancy to mother and child and the magnitude of the problem are enormous. However, we have very little information from Asia and Latin America, and even for Africa we are currently unable to make an evidence-based statement on whether the overall burden of malaria in pregnancy has increased, decreased, or remained at a steady state in the past few decades. At present, there are substantial knowledge
Conclusion
Although much is known about the epidemiology and burden of malaria in pregnancy, there remain substantial gaps in our understanding that impede our ability to control this important public-health problem. The effect of infection in the first trimester, and the longer term effects of malaria in pregnancy beyond infancy are largely unknown and may be substantial. Better estimates are also needed of the effects of malaria in pregnancy outside Africa, and on maternal morbidity and mortality
Search strategy and selection criteria
References (112)
- et al.
Malaria during pregnancy in an area of unstable endemicity
Trans R Soc Trop Med Hyg
(1991) - et al.
The epidemiology of severe malaria in an area of low transmission in Thailand
Trans R Soc Trop Med Hyg
(1997) - et al.
Prevalence and risk factors for anaemia in pregnant women of eastern Sudan
Trans R Soc Trop Med Hyg
(2005) - et al.
Effects of Plasmodium vivax malaria in pregnancy
Lancet
(1999) - et al.
The sick placenta—the role of malaria
Placenta
(2004) - et al.
Malaria chemoprophylaxis, birth weight and child survival
Trans R Soc Trop Med Hyg
(1992) - et al.
Rapid spontaneous postpartum clearance of Plasmodium falciparum parasitaemia in African women
Lancet
(1988) - et al.
A longitudinal study of splenomegaly in pregnancy in a malaria endemic area in Papua New Guinea
Trans R Soc Trop Med Hyg
(1988) - et al.
Malaria-related anaemia
Parasitol Today
(2000) - et al.
Malaria as a cause of severe anaemia in pregnancy
Lancet
(2002)
An analysis of anemia and pregnancy-related maternal mortality
J Nutr
Malaria in pregnancy as an indirect cause of infant mortality in sub-Saharan Africa
Trans R Soc Trop Med Hyg
Malaria in pregnancy and the endemicity spectrum: what can we learn?
Trends Parasitol
Cost-effectiveness of malaria control in sub-Saharan Africa
Lancet
Reduced transfer of tetanus antibodies with placental malaria
Lancet
Congenital malaria: a report of four cases and a review
J Pediatr
Parasites and pregnancy: the problems of malaria and toxoplasmosis
Clin Perinatol
Long-term consequences of low birth weight
Kidney Int Suppl
Prevalence of low height and related risk factors in school children from Corrientes (Argentina)
An Esp Pediatr
Pregnancy malaria throughout history: dangerous labors
Malaria infection as it occurs in late pregnancy, its relationship to labour and early infancy
Ann Trop Med Parasitol
Some observations on malaria occurring in association with pregnancy
J Obstet Gynaecol Br Empire
The influence of malarial infection of the placenta on the incidence of prematurity
Bull World Health Organ
Malaria and prematurity in the western region of Nigeria
Br Med J
Malaria, anaemia and pregnancy
Ann Trop Med Parasitol
Low birth-weight and malarial infection of the placenta
Bull World Health Organ
Malaria at delivery in Abidjan
Helv Paediatr Acta Suppl
Malaria infection of the placenta and its influence on the incidence of prematurity in eastern Nigeria
Bull World Health Organ
An analysis of malaria in pregnancy in Africa
Bull World Health Organ
The burden of malaria in pregnancy in malaria-endemic areas
Am J Trop Med Hyg
Impact of malaria during pregnancy on low birth weight in sub-Saharan Africa
Clin Microbiol Rev
Evaluation of a malaria rapid diagnostic test for assessing the burden of malaria during pregnancy
Am J Trop Med Hyg
A community randomized controlled trial of insecticide-treated bednets for the prevention of malaria and anaemia among primigravid women on the Kenyan coast
Trop Med Int Health
The global distribution of clinical episodes of Plasmodium falciparum malaria
Nature
The effects of Plasmodium falciparum and P vivax infections on placental histopathology in an area of low malaria transmission
Am J Trop Med Hyg
Malaria prevention during pregnancy in unstable transmission areas: the highlands of Madagascar
Trop Med Int Health
Malaria parasitemia during delivery
Saudi Med J
Unstable malaria transmission and maternal mortality—experiences from Rwanda
Trop Med Int Health
Low birthweight associated with maternal anaemia and Plasmodium falciparum infection during pregnancy, in a peri-urban/urban area of low endemicity in Uganda
Ann Trop Med Parasitol
Burden of malaria during pregnancy in areas of stable and unstable transmission in Ethiopia during a nonepidemic year
J Infect Dis
Plasmodium falciparum infection during pregnancy in an unstable transmission area in eastern Sudan
East Mediterr Health J
The effect of malarial infection on maternal-fetal outcome in Ecuador
J Matern Fetal Neonatal Med
Evaluation of a rapid diagnostic test for assessing the burden of malaria at delivery in India
Am J Trop Med Hyg
Permethrin-treated bed nets in the prevention of malaria and anemia in adolescent schoolgirls in western Kenya
Am J Trop Med Hyg
Malaria and anemia in antenatal women in Blantyre, Malawi: a twelve-month survey
Am J Trop Med Hyg
Plasmodium species mixed infections in two areas of Manhica District, Mozambique
Int J Biol Sci
Malaria in pregnant Cameroonian women: the effect of age and gravidity on submicroscopic and mixed-species infections and multiple parasite genotypes
Am J Trop Med Hyg
Increased susceptibility to malaria during the early postpartum period
N Engl J Med
Rolling back malaria in pregnancy
N Engl J Med
Clinical and parasitological characteristics of puerperal malaria
J Infect Dis
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