MicrobiologyBytes

Between a quarter and a third of pregnant women in sub-Saharan Africa, almost 7 million, are infected with hookworms and at increased risk of developing anaemia. Hookworms are parasitic worms which live in the intestine and can cause anaemia (lower than normal number of red blood cells in the blood). Their importance in causing anaemia during pregnancy has been poorly understood, and this has hampered effective lobbying for the inclusion of deworming drugs in maternal health care packages. By carrying out a systematic search of medical databases, reference lists, and unpublished data, the team was able to compare levels of haemoglobin (the oxygen-carrying part of red blood cells) according to the intensity of hookworm infection among the women studied. They found that increasing intensity of infection was associated with lower levels of haemoglobin. The authors estimate that 37.7 million women of reproductive age and 6.9 million pregnant women in sub-Saharan Africa were infected with hookworm in 2005, and were therefore at risk of anaemia. In many developing countries it is policy that pregnant women receive deworming treatment, but in practice coverage rates are often unacceptably low.

Hookworm-Related Anaemia among Pregnant Women: A Systematic Review. 2008 PLoS Negl Trop Dis 2(9): e291
Hookworm infection is among the major causes of anaemia in poor communities, but its importance in causing maternal anaemia is poorly understood, and this has hampered effective lobbying for the inclusion of anthelmintic treatment in maternal health packages. We sought to review existing evidence on the role of hookworm as a risk factor for anaemia among pregnant women. We also estimate the number of hookworm infections in pregnant women in sub-Saharan Africa (SSA). Structured searches using MEDLINE and EMBASE as well as manual searches of reference lists were conducted, and unpublished data were obtained by contacting authors. Papers were independently reviewed by two authors, and relevant data were extracted. We compared haemoglobin concentration (Hb) according to intensity of hookworm infection and calculated standardised mean differences and 95% confidence intervals. To estimate the number of pregnant women, we used population surfaces and a spatial model of hookworm prevalence. One hundred and five reports were screened and 19 were eligible for inclusion: 13 cross-sectional studies, 2 randomised controlled trials, 2 non-randomised treatment trials and 2 observational studies. Comparing uninfected women and women lightly (1 1,999 eggs/gram [epg]) infected with hookworm, the standardised mean difference (SMD) was 0.24 (95% CI: 0.36 to 0.13). The SMD between women heavily (4000+ epg) infected and those lightly infected was 0.57 (95% CI: 0.87 to 0.26). All identified intervention studies showed a benefit of deworming for maternal or child health, but since a variety of outcomes measures were employed, quantitative evaluation was not possible. We estimate that 37.7 million women of reproductive age in SSA are infected with hookworm in 2005 and that approximately 6.9 million pregnant women are infected. Evidence indicates that increasing hookworm infection intensity is associated with lower haemoglobin levels in pregnant women in poor countries. There are insufficient data to quantify the benefits of deworming, and further studies are warranted. Given that between a quarter and a third of pregnant women in SSA are infected with hookworm and at risk of preventable hookworm-related anaemia, efforts should be made to increase the coverage of anthelmintic treatment among pregnant women.

Related:

• Multiple parasite infections synergize to increase the risk of anemia

Tags: Biology, Health, Medicine, Microbiology, Parasitology, Science

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