Hepatitis E Virus in the Terai of Nepal: Community-Based Cohort Study of Pregnant Women in Sarlahi District and Investigation of the 2014 Outbreak in Biratnagar, Morang District
Krain, Lisa J.
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In South Asia, hepatitis E virus (HEV) is an important cause of morbidity and mortality and poses a special threat to pregnant women. However, the burden of both infection and illness in the Terai of Nepal have received scant attention. We enrolled 2363 pregnant women in a community-based cohort study in Sarlahi District and followed threm through three months postpartum. Baseline anti-HEV IgG seroprevalence was 11.7% [95% confidence interval (CI): 10.2%-13.3%] and varied with age, socioeconomic factors, and meat consumption, but not with water source or latrine access. The incidence of HEV seroconversion was 32.3/1000 person-years (p*y) during pregnancy [95% CI: 14.8 to 61.3/1000 p*y] and 44.3/1000 p*y overall [95% CI: 27.1 to 68.4/1000 p*y]. One acute hepatitis E case (genotype 1) was confirmed, but most hepatitis-like illnesses were not attributable to hepatitis A, B, C, or E. Jaundice was linked to 1/2 maternal deaths. Earlier and extended serologic monitoring would permit improved surveillance of pregnancy outcomes and antibody kinetics. Environmental testing could help clarify exposure pathways and seasonal patterns. A large outbreak of waterborne hepatitis E occurred in Biratnagar municipality in 2014. We tested sera collected from healthy adults in Biratnagar and Dharan before the outbreak and from patients seen at three hospitals in Biratnagar during the outbreak. The population seroprevalence of anti-HEV IgG was low in Biratnagar (~5.6%) before the outbreak. Among 450 oubtreak patients, 42.2% were IgG+, 14.7% IgM+, and 2.9% HEV Ag+. Acute HEV markers varied geographically and by hospital. The outbreak underscores the need for access to clean water, and for improved epidemiologic surveillance and response. Hepatitis E virus threatens public health in the Terai. Rural and urban populations in Nepal remain highly vulnerable to infection, disease, and mortality due to HEV. Improvements in water, sanitation, and hygiene are needed to prevent both sporadic and epidemic hepatitis E, especially as development of the Terai increases. Targeted interventions may help alleviate the increased burden of disease borne by pregnant women, individuals with chronic medical conditions, and members of socially- and economically-disadvantaged groups.