Over a 2-year period, from 2016 to 2018, reports of hepatitis A infections in the United States increased by 294% compared with 2013 to 2015, according to the CDC.
The outbreaks occurred in persons who consumed contaminated food items, among men who have sex with men, and primarily, among drug users and the homeless, according to the report in Morbidity and Mortality Weekly Report.
Noting that hepatitis A is a vaccine-preventable viral infection of the liver that is primarily transmitted through consumption of microscopic amounts of feces, the CDC recommends that increasing vaccination among groups at risk for the infection could both halt ongoing outbreaks and prevent future ones.
Background information in the report points out that hepatitis A is the most common cause of viral hepatitis worldwide, typically causing acute and self-limited symptoms. It is rare for liver failure and death to occur, according to the article.
The CDC says that rates of hepatitis A virus (HAV) had declined by approximately 95% from 1996 to 2011, but that from 2016 to 2018, public-health officials received about 15,000 reports of HAV infections from U.S. states and territories, indicating a recent increase in transmission.
“Since 2017, the vast majority of these reports were related to multiple outbreaks of infections among persons reporting drug use or homelessness,” the CDC authors write. “In addition, increases of HAV (hepatitis A virus) infections have also occurred among men who have sex with men (MSM) and, to a much lesser degree, in association with consumption of imported HAV-contaminated food.”
This occurrence was sharply different from the past, when, according to the CDC, “outbreaks of hepatitis A virus infections occurred every 10–15 years and were associated with asymptomatic children. With the widespread adoption of universal childhood vaccination recommendations, asymptomatic children are no longer the main drivers of hepatitis A outbreaks.”
Part of the problem, the authors point out, is that while the overall incidence rate of HAV infections has decreased within all age groups, “a large population of susceptible, unvaccinated adults who were not infected by being exposed to the virus during childhood remain vulnerable to infection by contaminated foods (typically imported from countries with endemic HAV transmission) and recently, on a much larger scale, through behaviors that increase risk for infection in certain vulnerable populations, such as drug use.”
Public-health officials are calling for more emphasis on immunization, noting, “Decreasing new infections from hepatitis A virus can be achieved and sustained by maintaining a high level of population immunity through vaccination.”
At this point, however, there is no universal vaccination recommendation for adults in the U.S., although vaccination is recommended for adults who plan travel to HAV-endemic countries, men who have sex with men, drug users, patients with chronic liver disease, and, more recently, the homeless.
“Continued efforts to increase hepatitis A vaccination coverage among the ACIP-recommended risk groups is vital to halting the current hepatitis A outbreaks and reducing overall hepatitis A incidence in the United States,” the report concludes.
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