Helminth Infections in Pregnant Women

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


March 14, 2014

Helminth Treatment in Pregnancy

Albendazole is a benzimidazole that can be used in pregnancy to treat intestinal roundworms, such as A duodenale, N americanus, and A lumbricoides. Ivermectin is an antihelminthic medication; it is a gamma-aminobutyric acid (GABA) agonist that is metabolized by the liver (cytochrome P450 3A4) and used to treat invasive roundworms, such as S stercoralis, O volvulus, W bancrofti, and L loa.

Metronidazole is a nitroimidazole derivative used as an antimicrobial agent for anaerobic infections as well as for treatment of intestinal protozoa, such as giardia. Diethylcarbamazine can be used to treat disease caused by trematodes, including lymphatic filariasis; however, close monitoring is necessary in areas with overlapping onchocerciasis and loiasis.

Praziquantel can be given in pregnancy and is used to treat infection with invasive flatworms, such as schistosomiasis, and intestinal flatworms, such as Taenia solium. However, it is metabolized by the liver and has drug/drug interactions with cytochrome P450 inducers, such as rifampin.

Helminth Infection Eradication

Environmental control and "rapid impact packages" for mass antihelminth drug administration are staples of the helminth infection eradication effort. In the past, antihelminth medications were avoided in pregnant and lactating women out of safety concerns for the fetus.[1] In areas where helminth infections are endemic, treatment regimens are delayed for years because many women are pregnant and breastfeeding for more than one half of their reproductive lives. This delay has led to significant morbidity in mothers and their infants.[5,8]

The risk/benefit analysis of preventing anemia, severe malnutrition, and genitourinary pathology in women has prompted a more aggressive treatment recommendation during pregnancy.[8] International groups, such as the WHO, have supported the use of antihelminth medications -- including benzimidazoles (albendazole and mebendazole) and praziquantel -- during pregnancy in endemic areas, particularly where the prevalence of hookworm infection exceeds 20%-30%.[8,9,11] It has been recommended that treatment be part of routine antenatal care service during the second- or third-trimester routine visit.[11] These recommendations have been based on a small number of studies, which have had inconclusive results with respect to improvement in maternal morbidity.[5]

In 2009, a Cochrane review[6] of 9 studies and a total of 1329 pregnant women did not produce sufficient evidence to recommend the use of antihelminth medications after the first trimester of pregnancy and highlighted the need for larger-scale randomized controlled trials. Subsequently, in 2010, a large study[5] in Uganda of 2515 pregnant women showed a maternal benefit in preventing anemia with administration of albendazole during the second and third trimesters of pregnancy only in women with moderate to heavy hookworm infection. This study suggests that deworming may be most effective in areas where both the prevalence of anemia and the intensity of hookworms are high; in addition, no congenital anomalies were associated with the use of intrapartum antihelminth medications.[5]

Whereas trials have validated antihelminth treatment during pregnancy for mothers in endemic areas with high disease burden, infant outcomes still are in need of validation.[2] Some reports suggest that drugs that are effective against intestinal helminth lead to significant improvements in child weight, weight for age, and weight for height; however, no large randomized controlled trials have been done to date.[3,11]

At this time, it is recommended that antihelminth treatment in areas of high worm burden be integrated into routine antenatal care visits during the second or third trimester.[11] Furthermore, development of vaccines for helminth infections, such as hookworm, are currently under way and could provide significant benefit for pregnant women and their infants in helminth-endemic areas.


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