Investigation of Two Outbreaks of Hepatitis A Virus Infections Linked to Fresh and Frozen Strawberries Imported from Mexico - 2022-2023

Abstract

Foodborne hepatitis A illnesses and outbreaks have been associated with the consumption of ready-to-eat foods contaminated with the feces of person(s) shedding hepatitis A virus (HAV). Outbreaks have been linked to fresh and frozen produce imported from countries where HAV is endemic, hygiene and sanitation are inadequate, or food safety standards are lacking or unenforced. In 2022 and 2023, federal, state, and international partners investigated two multijurisdictional outbreaks of infections involving the same HAV genotype IA strain linked to fresh and frozen organic strawberries sourced from a single grower in Baja California, Mexico. These resulted in 39 reported cases in the U.S. and Canada, 21 hospitalizations, and no reported deaths. The United States Food and Drug Administration (FDA), Canadian Food Inspection Agency, and U.S. state partners conducted traceback investigations for fresh strawberries in 2022, while FDA and U.S. state partners traced back frozen strawberries in 2023. Based on the traceback investigations, implicated strawberries were harvested during the 2022 growing season and sold to fresh and frozen berry markets. During a farm inspection in Mexico in 2023, gaps were observed in agricultural practices that could have contributed to the contamination of strawberries with HAV. FDA did not detect HAV in the two frozen strawberry samples linked to the recalled lots or environmental water samples collected at the implicated grower in 2023; no samples were collected during the 2022 investigation. Indicator organisms associated with human fecal contamination (male-specific coliphage and crAssphge) were detected in environmental water. Challenges in these investigations included limited recall of food exposures, exposures associated with multiple purchase dates, commingling of strawberries within the frozen market supply chains, and complexities with communicating these outbreak investigations to the public.

Keywords: Foodborne outbreaks; Hepatitis A; Imports; Strawberries.