2189. Hepatitis A Outbreak in San Diego County, 2016–2017: A Morphologic and Epidemiologic Review

BACKGROUND: Hepatitis A rate has declined by 95% in the United States since routine vaccination begun in the late 1990s. In 2014, a total of 1,239 cases of HAV were reported from 50 states to CDC. Per San Diego (SD) County Public Health Department, on average 20 cases/year are reported locally. The recent hepatitis A outbreak in SD County, which started in late 2016, caused 588 new cases. METHODS: Epidemiologic data on hepatitis A cases was provided by the SD Public Health Department. Genetic evaluation was performed on all cases by the Health Department to identify the hepatitis A viral (HAV) strain. UCSD records and available liver biopsies were reviewed for the patients who were treated at UCSD. RESULTS: SD County reported 588 new cases, 403 (68%) hospitalization and 20 deaths (3.4%), with the following demographic distribution: Age range of 5–87 (median 43), 69% male and 31% female. One hundred and fifty-four of the 588 patients were treated at UCSD. The demographics of UCSD patients are as follows: Age range of 23–100 (median 45), 71% male (median age 47) and 29% female (median age 39). Concurrent hepatitis B (in 5.5%) and hepatitis C (in 18.5%) were present. Clinically relapsing (10%) and cholestatic (5%) hepatitis were seen. The infection has disproportionately affected the homeless and IV drug user population. Morphologically, features of severely active hepatitis with confluent and bridging necrosis, lymphoplasmacytic inflammation, canalicular and hepatocytic cholestasis and bile duct injury were present. HAV genotype 1b was identified by the SD Health department in all reported cases. CONCLUSION: The hepatitis A outbreak affected 588 individuals. An epidemiologic and morphologic review of the cases with a focus on the UCSD patients was performed. No common sources of food, beverage or drugs have been identified that have contributed to this outbreak. Mode of distribution is likely direct person to person transmission. The health department initiated an extensive public vaccination and education campaign, distributed hygiene kits, deployed portable bathroom and hand washing and declared a local public health emergency. Due to the extensive public health campaign, the outbreak seems to be under control as of January 2018. DISCLOSURES: All authors: No reported disclosures.