Hepatitis A Outbreak Among Persons Experiencing Homelessness—Maricopa County, Arizona, 2017

BACKGROUND: Hepatitis A virus (HAV) outbreaks can occur in settings with poor sanitation and crowding, including homeless shelters. On March 29, the Maricopa County Department of Public Health identified three confirmed HAV cases among homeless persons using services at one campus. We sought to determine outbreak source and scope and prevent further spread. METHODS: Cases were defined as having symptoms of acute hepatitis and a positive IgM anti-HAV test in persons with a history of homelessness or exposure or epidemiologic link to the campus and onset in 2017. Case-finding included enhanced surveillance with outreach to campus staff and healthcare providers who serve homeless persons. In-person interviews were conducted with campus HAV vaccination clinic attendees on April 4 and 11. To assess factors associated with HAV infection, a case–control study was conducted; campus clients or staff without a HAV diagnosis were controls. An environmental inspection was conducted. CDC performed HAV molecular sequencing. RESULTS: Twelve cases were identified, one by facility reporting, three by healthcare reporting, and eight by enhanced surveillance. Illness onsets were February 15–April 27; mean age was 47 years; 50% were male. The patient with the earliest onset arrived ~February 5 from San Diego, California, an area with an ongoing HAV outbreak. No campus food safety concerns were identified; educational flyers, soap, and alcohol-based hand sanitizer were provided to the campus. HAV vaccine was administered to 221 (22%) of ~1,000 clients and 105 (42%) of 250 staff who chose to attend the clinics. Ten cases and 343 controls were enrolled in the case–control study; not all questions were answered. Neither eating meals on campus (P = 0.71) nor sleeping on campus (P = 0.75) were associated with HAV. Fewer cases (57%) than controls (78%) reported always washing their hands before eating (P = 0.18). HAV isolated from 3 cases was molecularly identical to San Diego isolates. CONCLUSION: Molecular and epidemiologic data support that this HAV outbreak among homeless persons was associated with the San Diego outbreak. Crowding and suboptimal hygiene practices might have facilitated campus transmission. Expeditious vaccination might have slowed spread; surveillance is ongoing. DISCLOSURES: All authors: No reported disclosures.