Insight into an acute hepatitis A outbreak in Indiana

Hepatitis A virus (HAV) infection causes an acute enteric hepatitis associated with substantial morbidity and mortality, particularly in older individuals. Incidence of HAV infection is low in the United States, mostly related to consumption of contaminated food. Starting in 2017, Indiana reported a large HAV outbreak. We sought to characterize the risk-exposures, clinical features and outcomes of HAV and examine the differences based on underlying cirrhosis and age. Adults ≥18 years diagnosed with HAV between January 2017 and April 2019 at two large healthcare systems in Indiana were identified. Demographic data, risk-exposures, clinical features, laboratory data and clinical outcomes were collected for analysis. The HAV cohort constituted 264 individuals with mean age of 41-years, 62% male and 94% Caucasian. Risk-exposures identified were illicit drug use (74%), food-borne (15%), person-to-person (11%) and incarceration (11%). Mortality rate was 2%, acute liver failure (ALF) was seen in 4% and acute on chronic liver failure (ACLF) was seen in 30% (6 of 20 with underlying cirrhosis). Admission MELD score was the only factor associated with ALF [OR = 1.17 (1.08-1.2), p < 0.0001], on multivariable logistic regression analysis. Higher proportion of individuals with underlying cirrhosis developed acute kidney injury (AKI) (26% vs. 9%, p = 0.03), ascites (45% vs. 11%, p < 0.0001) and hepatic encephalopathy (35% vs. 4%, p < 0.0001). In conclusion, illicit drug use was the predominant risk-exposure in the current HAV outbreak, which was associated with 2% mortality rate, and those with cirrhosis had worse outcomes (AKI, ascites and HE), of whom 30% developed ACLF.