Outbreak of hepatitis A in the USA associated with frozen pomegranate arils imported from Turkey: an epidemiological case study.

Collier MG1, Khudyakov YE2, Selvage D3, Adams-Cameron M3, Epson E4, Cronquist A5, Jervis RH5, Lamba K6, Kimura AC6, Sowadsky R7, Hassan R8, Park SY9, Garza E10, Elliott AJ11, Rotstein DS12, Beal J12, Kuntz T12, Lance SE13, Dreisch R12, Wise ME14, Nelson NP2, Suryaprasad A2, Drobeniuc J2, Holmberg SD2, Xu F2; Hepatitis A Outbreak Investigation Team.

Abstract

BACKGROUND:

In May, 2013, an outbreak of symptomatic hepatitis A virus infections occurred in the USA. Federal, state, and local public health officials investigated the cause of the outbreak and instituted actions to control its spread. We investigated the source of the outbreak and assessed the public health measures used.

METHODS:

We interviewed patients, obtained their shopping information, and did genetic analysis of hepatitis A virus recovered from patients' serum and stool samples. We tested products for the virus and traced supply chains.

FINDINGS:

Of 165 patients identified from ten states, 69 (42%) were admitted to hospital, two developed fulminant hepatitis, and one needed a liver transplant; none died. Illness onset occurred from March 31 to Aug 12, 2013. The median age of patients was 47 years (IQR 35-58) and 91 (55%) were women. 153 patients (93%) reported consuming product B from retailer A. 40 patients (24%) had product B in their freezers, and 113 (68%) bought it according to data from retailer A. Hepatitis A virus genotype IB, uncommon in the Americas, was recovered from specimens from 117 people with hepatitis A virus illness. Pomegranate arils that were imported from Turkey--where genotype IB is common--were identified in product B. No hepatitis A virus was detected in product B.

INTERPRETATION:

Imported frozen pomegranate arils were identified as the vehicle early in the investigation by combining epidemiology--with data from several sources--genetic analysis of patient samples, and product tracing. Product B was removed from store shelves, the public were warned not to eat product B, product recalls took place, and postexposure prophylaxis with both hepatitis A virus vaccine and immunoglobulin was provided. Our findings show that modern public health actions can help rapidly detect and control hepatitis A virus illness caused by imported food. Our findings show that postexposure prophylaxis can successfully prevent hepatitis A illness when a specific product is identified. Imported food products combined with waning immunity in some adult populations might make this type of intervention necessary in the future.