Helminth Infections in Pregnant Women

Jill E. Weatherhead, MD; Laila E. Woc-Colburn, MD, DTM&H


March 14, 2014

Hookworm Infections

Hookworm infections, caused by N americanus and A duodenale, are typically found in underdeveloped regions of sub-Saharan Africa, South and East Asia, and Central and South America.[1] In sub-Saharan Africa, approximately 200 million cases of hookworm infection occur annually. Hookworm is common in young adulthood and is often seen in adolescent girls and women of reproductive age.[1]

Hookworm and Pregnancy

One fourth to one third of all pregnancies in sub-Saharan Africa are affected by hookworm infection, which increases risk for anemia and malnutrition in the mother.[1,9] Both species of hookworm attach to the inner wall of the small intestine, where they induce mechanical laceration and enzymatic damage to the mucosa of small intestines. Each individual worm leads to 0.05-0.25 mL of blood loss daily.[1,11]

This chronic gastrointestinal blood loss causes a hypochromic, microcytic anemia as well as the anemia of chronic disease that accompanies chronic inflammation.[11] A study of pregnant women in Peru showed a direct association between moderate to heavy hookworm infection and significant anemia, an association that was strengthened when women had polyparasitic infection with Trichuris.[9] Chronic infection with hookworm can also lead to malabsorption and appetite inhibition, which in turn results in iron, zinc, and protein deficiencies.[11]

Owing to these severe risks to both mothers and infants, since 1994 the World Health Organization (WHO) has recommend hookworm treatment during pregnancy in endemic areas. Despite this recommendation, many regions in the world have not adopted this practice, primarily because of concerns about medication safety in the developing fetus.[11]


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