|AFRICA MALARIA REPORT 2003|
|4. Malaria during pregnancy|
Malaria infection during pregnancy is a major public health problem in tropical and subtropical regions throughout the world. In most endemic areas of Africa, pregnant women are the main adult risk group for malaria. The main burden of malaria infection during pregnancy results from infection with Plasmodium falciparum. The impact of the other three human malaria parasites (P. vivax, P. malariae, and P. ovale) is less clear. Every year at least 30 million women in malarious areas of Africa become pregnant; most of these women live in areas of relatively stable malaria transmission.
The symptoms and complications of malaria during pregnancy differ with the intensity of malaria transmission and thus with the level of immunity acquired by the pregnant woman (2). Since malaria transmission intensity may vary within the same country from areas of relatively stable transmission to areas of unstable or epidemic transmission, the clinical picture of malaria infection during pregnancy may likewise range from asymptomatic to severe, life-threatening illness.
In areas of epidemic or low (unstable) malaria transmission, adult women have not acquired any significant level of immunity and usually become ill when infected with P. falciparum. For pregnant women in these areas the risk of developing severe malaria is 2-3 times higher than that for non-pregnant women living in the same area. Maternal death may result either directly from severe malaria or indirectly from malaria-related severe anaemia. In addition, malaria may result in a range of adverse pregnancy outcomes, including low birth weight, spontaneous abortion, and neonatal death (Figure 4.1).
In areas of high and moderate (stable) malaria transmission, most adult women have developed sufficient immunity that, even during pregnancy, P. falciparum infection does not usually result in fever or other clinical symptoms. In these areas, the principal impact of malaria infection is malaria-related anaemia in the mother and the presence of parasites in the placenta. The resulting impairment of fetal nutrition contributes to low birth weight and is a leading cause of poorer infant survival and development (Figure 4.1). In areas of Africa with stable malaria transmission, P. falciparum infection during pregnancy is estimated to cause an estimated 75 000 to 200 000 infant deaths each year (3).
Despite the toll that malaria exacts on pregnant women and their infants, this was - until recently - a relatively neglected problem, with less than 5% of pregnant women having access to effective interventions. During the past decade, however, potentially more effective strategies for prevention and control of malaria in pregnancy have been developed and shown to have a remarkable impact on the health of mothers and infants.
Intermittent preventive treatment (IPT)
For many years WHO recommended that pregnant women in malaria endemic areas should receive an initial antimalarial treatment dose on their first contact with antenatal services, followed by weekly chemoprophylaxis (given at less than therapeutic dose) with an effective and safe antimalarial drug (4). In most countries in Africa, chloroquine (CQ) has been the drug of choice. However, the emergence and spread of CQ-resistant falciparum malaria, poor patient compliance with multiple doses, and a high incidence of CQ-induced pruritus have limited the effectiveness and hence the implementation of this policy.
In 2000, the WHO Expert Committee on Malaria recommended that intermittent treatment with an effective, preferably one-dose, antimalarial drug, should be made available as a routine part of antenatal care to women in their first and second pregnancies in highly endemic areas (5). At present, sulfadoxine-pyrimethamine (SP) - given at a therapeutic dose - is the single-dose antimalarial with the best overall effectiveness for prevention of malaria in pregnancy in areas with high transmission, and low resistance to SP. Other antimalarials are being evaluated for potential use in IPT.
Studies in Kenya (6,7) and Malawi (8) have shown that IPT with at least two treatment doses of SP is highly effective in reducing the proportion of women with anaemia and placental malaria infection at delivery. The benefits of IPT for both maternal and infant health have been seen in a range of different malaria transmission settings (Figures 4.2-4.4).
If used during pregnancy in areas of stable malaria transmission, ITNs reduce the overall risk of morbidity and mortality among pregnant women and their infants. A trial in the Gambia found that, during the rainy season in villages where ITNs were used, the prevalence of malaria infection among pregnant women was lower and fewer babies were classified as premature (9). Further evidence comes from a recent study in a highly malarious area of Kenya. During the first four pregnancies, women who were protected by ITNs at night gave birth to 25% fewer premature or small-for-gestational-age babies than women who did not sleep under ITNs (10) (Figure 4.5).
Case management of malaria illness
Malaria in pregnant women requires immediate treatment, focusing on complete cure of the infection. Each country in malaria-endemic areas of Africa needs a policy that guides effective management of malaria in pregnant women. Collaboration between malaria control programme and reproductive health programme staff can facilitate the development of systematic management protocols and drug supply strategies (11).
Weekly CQ chemoprophylaxis was compared with two-dose IPT using SP in primigravidae in an area of moderate to high malaria transmission: IPT-SP proved to be more cost-effective than CQ chemoprophylaxis, largely because of lower costs and higher compliance with SP (12). In a further cost-effectiveness analysis, three different SP regimens were compared with febrile case management using SP for a hypothetical cohort of 10 000 pregnant women in Kenya. The results suggested that the two-dose SP regimen (when the costs only of antenatal care are considered and at HIV seroprevalence below 10%) would be the least expensive strategy for preventing low birth weight (13).
ITN use by children has been shown to be cost-effective in several settings (14,15). The substantial benefit of ITNs in reducing the burden of malaria during pregnancy makes it likely that the cost-effectiveness of ITN use by pregnant women will be of similar attractiveness to that for children.
WHO recommends that IPT be administered to pregnant women during routine visits to antenatal clinics. As recent surveys confirm, at least two-thirds of pregnant women in most countries do have access to, and use, antenatal care, and most of them attend antenatal clinics at least twice (Figure 4.6). The high level of antenatal care coverage and use provides a unique opportunity to deliver prevention packages to pregnant women in the Africa region.
Prevention with IPT and ITNs
Coverage of pregnant women with IPT and ITNs is a fundamental part of prevention of malaria during pregnancy. Although there are examples of successful delivery of IPT and ITNs through antenatal clinics, large-scale programmes to deliver these prevention tools to pregnant women are only now being developed. Thus, data on IPT and ITN coverage are limited at present.
Surveys conducted on a national scale indicate that net use among women of reproductive age (15-49 years) - an indication of use by pregnant women - remains very low. Among pregnant women, coverage with any net (treated or untreated) was less than 10% in three of the four countries for which recent data were available. Coverage with ITNs in these three countries was even lower, at 3% or less (Figure 4.7). As countries accelerate efforts to control malaria during pregnancy, ITN coverage is expected to increase.
Timely antenatal clinic attendance is key for delivering the prevention package to pregnant women. Some 40% of pregnant African women present for the first time to antenatal clinics in the second trimester of pregnancy, and about 25% come for the first time in the third trimester (16) (Figure 4.8). This means that at least the first dose of IPT could be given in time to most pregnant women. The ITN part of the prevention package delivered during the first antenatal clinic visit would provide additional protection for the mother during the remainder of the time of pregnancy and into the post-partum period, as well as protection for the newborn through at least the first year of life.
High coverage with antenatal care, i.e. a minimum of two visits to an antenatal clinic, does not necessarily translate into full coverage with IPT.
However, a multidisciplinary team in the Blantyre district in Malawi (population about 950 000, with approximately 35 000 births annually) focused from mid-2001 through 2002 on resolving barriers to complete coverage with IPT. Improved education about the benefit of IPT and modified recommendations for the scheduled antenatal clinic visits after quickening resulted in a rapid increase to 75% coverage, with two doses of SP in pregnant women (Figure 4.9).
A striking determinant of attendance at antenatal clinics is household wealth. According to a recent study, poor women are less likely to use antenatal services than are women from the richest households (16) (Figure 4.10). In seven African countries south of the Sahara for which recent data are available, the percentage of rich women attending antenatal clinics was at least twice that of poor women. The same study indicated that antenatal care coverage was significantly higher in urban than in rural areas.
Nationally representative surveys confirm similar difference in coverage of pregnant with chemoprophylaxis, IPT, or nets (Figures 4.11 and 4.12). Women living in rural areas were less likely to receive chemoprophylaxis or, in Malawi, IPT with SP.
At present, strategies to ensure safe pregnancy in malaria-endemic areas are planned with a focus initially on strengthening malaria preventive services and correct case management for pregnant women attending antenatal care. A number of opportunities will facilitate the accelerated implementation of malaria control during pregnancy:
Making Pregnancy Safer:
In support of the Safe Motherhood Initiative, the WHO Making Pregnancy Safer focuses on effective evidence-based interventions that target the major causes of maternal and newborn morbidity and mortality. Making Pregnancy Safer aims to strengthen health systems and to identify actions at community level needed to ensure access to essential care for pregnant women and their newborns.
Skilled attendance at delivery and provision of an appropriate and effective continuum of antenatal and perinatal care are particularly important in this initiative.
The evidence-based interventions of Making Pregnancy Safer focus on six areas:
Commitment to accelerating prevention and control of malaria during pregnancy
Countries are developing national policies on the prevention of malaria in pregnancy according to WHO recommendations and have started to document experiences from control efforts.
In March 2002, a technical meeting on malaria prevention and control during pregnancy was held in Malawi where reproductive health and malaria staff from five countries, Kenya, Malawi, Uganda, the United Republic of Tanzania, and Zambia, came together to discuss a coordinated approach to accelerating prevention and control of malaria in pregnancy. The participants and RBM partners have agreed to forge the East and Southern Africa Coalition for malaria prevention and control during pregnancy, MIPESA. The coalition was inaugurated in June 2002.
This coalition is a unique concerted effort in which national reproductive health programmes, Making Pregnancy Safer and malaria control programmes are coming together
1. The African summit on Roll Back Malaria, Abuja, Nigeria, 25 April 2000. Geneva, World Health Organization, 2000 (document WHO/CDS/RBM/2000.17).
2. Strategic Framework for Malaria Control During Pregnancy in the WHO African Region. Geneva, World Health Organization, 2003 [final draft, in press].
3. Steketee RW et al. The burden of malaria in pregnancy in malaria-endemic areas. American Journal of Tropical Medicine and Hygiene, 2001, 64(1,2 S):28-35.
4. WHO Expert Committee on Malaria. Eighteenth report. Geneva, World Health Organization, 1986 (WHO Technical Report Series, No. 735).
5. WHO Expert Committee on Malaria. Twentieth report. Geneva, World Health Organization, 2000 (WHO Technical Report Series, No. 892).
6. Shulman CE et al. Intermittent sulphadoxine-pyrimethamine to prevent severe anaemia secondary to malaria in pregnancy: a randomised placebo-controlled trial. Lancet, 1999, 353:632-636.
7. Parise ME et al. Efficacy of sulfadoxine-pyrimethamine for prevention of placental malaria in an area of Kenya with a high prevalence of malaria and human immunodeficiency virus infection. American Journal of Tropical Medicine and Hygiene, 1998, 59(5):813-822.
8. Schultz LJ et al. The efficacy of antimalarial regimens containing sulfadoxine-pyrimethamine and/or chloroquine in preventing peripheral and placental Plasmodium falciparum infection among pregnant women in Malawi. American Journal of Tropical Medicine and Hygiene, 1994, 51(5):515-522.
9. D'Alessandro U et al. The impact of a national impregnated bed net programme on the outcome of pregnancy in primigravidae in The Gambia. Transactions of the Royal Society of Tropical Medicine and Hygiene, 1996, 90(5):487-492.
10. Kuile T et al. Permethrin-treated bednets reduce malaria in pregnancy in an area of intense perennial malaria transmission in western Kenya. American Journal of Tropical Medicine and Hygiene, 2003 [in press].
11. Managing complications in pregnancy and childbirth: a guide for midwives and doctors. Geneva, World Health Organization, 2000.
12. Goodman CA, Coleman PG, Mills AJ. The cost-effectiveness of antenatal malaria prevention in sub-Saharan Africa. American Journal of Tropical Medicine and Hygiene, 2001, 64(1,2 S):45-56.
13. Wolfe E et al. Cost-effectiveness of sulfadoxine-pyrimethamine for the prevention of malaria-associated low birth weight? American Journal of Tropical Medicine and Hygiene, 2001, 64(3,4):178-186.
14. Wiseman V et al. The cost-effectiveness of permethrin-treated bednets in an area of intense malaria transmission in western Kenya. American Journal of Tropical Medicine and Hygiene, 2003 [in press].
15. Goodman CA, Coleman PG, Mills AJ. Cost-effectiveness of malaria control in sub-Saharan Africa. Lancet, 1999, 354:378-385.
16. UNICEF, WHO. Antenatal care in developing countries: promises, achievements, and missed opportunities. An analysis of levels, trends and differentials, 1990-2001, 2003 [in preparation].
|Contents||AFRICA MALARIA REPORT 2003|