A study published today in the open-access journal PLoS Neglected Tropical Diseases reveals that between a quarter and a third of pregnant women in sub-Saharan Africa, or 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.
The study was conducted by Simon Brooker (a Reader at the London School of Hygiene & Tropical Medicine and a Wellcome Trust Career Development fellow currently based at KEMRI-Wellcome Trust Collaborative Programme, Nairobi), together with Peter Hotez (George Washington University and Sabin Vaccine Institute, United States) and Donald Bundy (The World Bank, United States).
By carrying out a systematic search of medical databases, reference lists, and unpublished data, the team was able to compare levels of haemoglobin (the oxygen-carrying part of red blood cells) according to the intensity of hookworm infection among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.
"Most of the studies we identified showed that hookworm was associated with maternal anaemia," says Brooker, "and that there are clear benefits of deworming for both maternal and child health." He adds, "In many developing countries it is policy that pregnant women receive deworming treatment, but in practice coverage rates are often unacceptably low. Therefore, we encourage that efforts are made to increase coverage of deworming among pregnant women in Africa."