Why hepatitis E kills so many pregnant women

"Our research group estimates that hepatitis E causes about 10,500 maternal deaths every year just in Southeast Asia," says Brittany Kmush, "and the nearly 30 percent fatality rate among pregnant women is as high as Ebola's during some outbreaks." (Credit: IFPRI -IMAGES/Flickr)

Low bodyweight, anemia, and other nutritional deficiencies put pregnant women at greater risk of getting hepatitis E, a disease particularly dangerous for expectant mothers in developing countries.

Researchers have known that as many as 30 percent of pregnant women who contract hepatitis E die from the viral infection, compared with a mortality rate of between 0.5 and 2 percent for all patients with the disease.

But scientists have not known—until now—what public health measures might help expectant mothers resist hepatitis E. The liver disease, spread by feces-contaminated water, is believed to be responsible for as many as 10 percent of all maternal deaths in Southeast Asia.

“For decades, we’ve been asking why pregnant women who get hepatitis E die at an alarming rate,” says Alain Labrique, associate professor of international health at Johns Hopkins University’s Bloomberg School of Public Health. “This research suggests that pre-existing differences could be the key we’ve been seeking.

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“These findings could pave the road for stepped-up nutritional monitoring of pregnant women in this part of the world and lead to recommendations for nutritional supplements.”

The study, published in the journal American Society of Tropical Medicine and Hygiene, identified anemia in 27.5 percent of women who became infected, compared with 10 percent of those in a control group of similar pregnant women who didn’t become sick.

Forty-five percent of hepatitis E-infected pregnant women were underweight, compared with a quarter of the control group. Women who were deficient in vitamin D and had lower levels of zinc also were more likely to be infected.

The study, conducted at the Bloomberg School’s flagship JiVitA Research Project in Bangladesh, also found that the women who became infected tended to have higher levels of both pro- and anti-inflammatory cytokines, important to immune system functioning. This suggests that pre-existing immune dysfunction may also increase the risk of getting hepatitis E or other infectious diseases.

For the study, researchers collected blood samples from 1,100 women living in northern Bangladesh: once early in pregnancy, again in the third trimester, and a third time three months after birth. Forty women became infected with the hepatitis E virus over the course of the study.

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The control group comprised non-infected pregnant women who, because of their ages and where they lived, were believed to have similar exposure to the virus or other external risk factors.

Roughly 20 million people are infected each year with hepatitis E, resulting in an estimated 70,000 deaths and 3,000 stillbirths annually in developing countries.

“Our research group estimates that hepatitis E causes about 10,500 maternal deaths every year just in Southeast Asia, and the nearly 30 percent fatality rate among pregnant women is as high as Ebola’s during some outbreaks,”says lead author Brittany Kmush, a doctoral student in international health.

“Most of the current knowledge about how hepatitis E affects pregnant women comes from studies looking at women who are already infected,”Labrique says. “This population-based study was able to look at the health status of pregnant women before they became infected. If we can better understand what predisposes pregnant women to infection, we could also develop better programs that prevent infection from ever occurring.”

The National Institutes of Health, the Bill and Melinda Gates Foundation, the Sight and Life Global Nutrition Research Institute, and the government of Bangladesh funded the work.

Source: Johns Hopkins University