Hepatitis A Cases Rose 294% in the United States, 2016–2018

This page summarizes a CDC report on hepatitis A in the United States from 2013 to 2018.

Hepatitis A is a vaccine-preventable viral infection of the liver, spread mainly through tiny amounts of feces, usually after close contact with an infected person. It is the most common cause of viral hepatitis worldwide. It usually causes a short, self-limited illness, though it can rarely lead to liver failure and death.

U.S. hepatitis A rates fell by about 95% from 1996 to 2011. But from 2016 to 2018, CDC received about 15,000 reports of infection from states and territories, and reports rose 294% compared with 2013–2015. Since 2017, most were linked to outbreaks among people reporting drug use or homelessness. Cases also rose among men who have sex with men, and to a much smaller degree from imported food contaminated with the virus.

Percentage change in reported hepatitis A cases by state, 2013–2015 compared with 2016–2018. CDC, MMWR.

By state

Eighteen states reported fewer cases in 2016–2018 than in 2013–2015, but nine states and Washington, D.C., saw increases of about 500%.

What the virus revealed

Specimens from confirmed cases were sent to CDC for genetic testing, and far more arrived as outbreaks grew:

Genotype IA has historically been the most common in North and South America, but IB predominated in the United States from 2013 to 2018, and IIIA, considered rare in the country, appeared in growing numbers. Combined with good epidemiologic data, this kind of molecular testing helps identify transmission networks and confirm the source of common-source outbreaks.

Why it happened

Hepatitis A outbreaks used to come every 10 to 15 years, driven by children without symptoms. Universal childhood vaccination ended that pattern. But many adults were neither vaccinated nor infected as children, so they remain susceptible, both to contaminated food, usually imported from countries where the virus is common, and, on a much larger scale recently, to transmission linked to risk behaviors such as drug use.

The answer: vaccination

Keeping population immunity high through vaccination can cut new infections and keep them down. There is no universal adult recommendation, but the Advisory Committee on Immunization Practices recommends hepatitis A vaccine for adults who plan to travel to countries where the virus is common, men who have sex with men, people who use drugs, people with chronic liver disease and, more recently, people experiencing homelessness. Raising coverage in these groups is vital to ending the outbreaks.

Sources

• Foster MA, Hofmeister MG, Kupronis BA, et al. "Increase in Hepatitis A Virus Infections — United States, 2013–2018." MMWR 68(18). https://www.cdc.gov/mmwr/volumes/68/wr/mm6818a2.htm
• ACIP hepatitis A recommendations: https://www.cdc.gov/mmwr/preview/mmwrhtml/rr5507a1.htm; hepatitis A case definition: https://wwwn.cdc.gov/nndss/conditions/hepatitis-a-acute/