SAN FRANCISCO — Acute hepatitis E is rare in the United States, but an increasing number of travelers to India and China could make the disease more common here, Gregory L. Armstrong, M.D., said at the annual meeting of the Infectious Diseases Society of America.
Most U.S. patients with hepatitis E have traveled to countries where the virus is endemic. Although hepatitis E shares many commonalities with hepatitis A, it has a number of unique characteristics—most notably severe disease during pregnancy, said Dr. Armstrong of the Centers for Disease Control and Prevention, Atlanta.
Clinically, acute hepatitis E is indistinguishable from acute hepatitis A, B, or C. Its clinical spectrum is highly variable, ranging from asymptomatic infection to fulminant hepatic failure. Hepatitis E disease is most severe when it is acquired in the third trimester of pregnancy, he said. The reasons for poor outcomes in pregnancy are unclear.
About half of pregnant women who acquire the virus during the third trimester remain asymptomatic. In the resource-poor settings where these cases usually occur, the other half of third-trimester infections result in acute hepatitis E, with fulminant hepatic failure in about a third and preterm delivery in about two-thirds of pregnant women with acute hepatitis E. Clinical outcome in infants also is variable, ranging from asymptomatic infection to hepatic necrosis.
Commercially available serologic assays to diagnose hepatitis E are not very sensitive or specific, and results must be interpreted based on the pretest probability of hepatitis E infection, he said. A better serologic assay developed by the National Institutes of Health is not commercially available. Viral RNA testing is even more accurate, but also is available only for research.
There is no specific antiviral therapy for hepatitis E; treatment is supportive care. There are no published data on the benefits of early delivery of the child in cases of acute hepatitis E during pregnancy.
Results of a phase II/III trial of a hepatitis E vaccine developed by the National Institutes of Health should be released soon. “Most people who work in this field feel that this vaccine is likely to be very effective,” Dr. Armstrong said.
There have been five domestically acquired cases of acute hepatitis E in addition to travel-related cases, he added. All five cases involved a viral genotype found in almost all U.S. pigs. Workers in the swine industry also have higher rates of hepatitis E antibodies.