Hepatitis C Outbreak Identification and Response in a High-Security Unit Within a California County Jail

Unregulated tattoos and injection drug use remain common risk factors for hepatitis C virus (HCV) transmission within correctional facilities. The Centers for Disease Control and Prevention recommends routine HCV screening at intake into a correctional facility and if risk or exposure is ongoing; however, risk behaviors may not be reported, thus increasing the risk for in-custody HCV transmission and outbreaks within the facility. This case study describes a multiwave HCV outbreak within a California county jail, including case demographics, clinical characteristics, risk factors, and factors that necessitated testing beyond routine screening at admission. Over a 12-month period beginning in late 2023, a total of 12 HCV cases were detected in a single high-security housing unit through a combination of routine screening, symptomatic testing, self-requested screening, and response testing. Recent tattooing (75%) and tattooing with shared ink (50%) were the most commonly reported risk factors, followed by 25% who reported sharing sharps or identifying as people who inject drugs. Of the five sequenced samples, three were genetically linked, and two had viral levels too low to sequence. The initial and ongoing outbreak response efforts can inform future policy and practice to prevent in-custody HCV transmission and outbreaks within correctional facilities.