Hepatitis A infections have surged in the United States in recent years, according to the Centers for Disease Control and Prevention.
Infections reported between 2016 to 2018 catapulted by 294 percent compared to the previous three-year stretch. That jump came despite a vaccine that provides up to 95 percent protection among healthy people for as many as 11 years.
The CDC primarily attributed the surge to increased infections among the homeless population and drug users. Increases also have occurred among men who have sex with other men and via contaminated food.
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More than 15,000 cases have been reported since the first hepatitis A outbreaks were confirmed in 2016. There have been 8,500 hospitalizations and 140 deaths.
The increase was outlined in the CDC's latest Morbidity and Mortality Weekly Report.
The virus can remain in feces and is transmitted when a contaminated hand touches a person's mouth. The disease infects the liver, causing symptoms of fatigue, low appetite, stomach pain, nausea and jaundice.
Hepatitis A outbreaks previously occurred every 10 to 15 years, mostly among asymptomatic children, the CDC said. But due to widespread adoption of childhood vaccinations, asymptomatic children are no longer the primary drivers of the virus.
Overall incident rates have decreased among all age groups, but large populations of unvaccinated adults who were not exposed to the virus as children remain vulnerable.
To combat the current outbreaks and prevent others, the CDC recommends increasing vaccination among at-risk groups.