Source identified in Hawaii Hepatitis A outbreak – NoroCORE Food Virology

Source identified in Hawaii Hepatitis A outbreak

Sushi on a plateA month ago, we posted about the hepatitis A virus outbreak in Hawaii that was unfolding. It looks like the puzzle is coming together, thanks to a lot of detective work by public health officials.

A couple of days ago, the Hawaii Department of Health identified raw scallops, specifically “Sea Port Bay Scallops” that were harvested in the Philippines and shipped through two distributors, as the likely source of the outbreak.

As a result, Genki Sushi, a chain of conveyor belt-style sushi restaurants, that had received the scallops, was ordered by the Hawaii State Department of Health to temporarily close ten of its restaurants on Oahu and Kauai. These establishments threw away food and disposable items like cups and napkins, as well as disinfected surfaces, and shared their invoices and other records with officials to aid the investigation. Genki Sushi restaurants on Maui and the Big Island have not been ordered to close because it has not been verified that the raw scallops were shipped to these locations.

To identify a single contaminated ingredient in a foodborne disease outbreak is impressive, let alone one with a month-long incubation period, that is served at multiple locations, in a locale where travelers are always entering and leaving the population (case in point, this author ate at the Kauai Genki location with her husband on their honeymoon), and where seafood, a potential source of the virus, is commonly consumed. Since hepatitis A is a durable virus and fecal-orally transmitted, it can also be a waterborne pathogen from human sewage or be spread through contact with contaminated surfaces, vastly broadening the realm of possible sources. In short, a round of applause is in order for the agencies who conducted the investigation!

So how did they hone in on the scallops? People from the Hawaii Department of Health, the FDA, and the CDC worked together on the case, and in addition to the epidemiological investigation there was a massive traceback investigation. A traceback is where food items eaten by sick individuals are compared and sometimes traced back along their production history to look for commonalities and potential sources. According to Hawaii’s State Epidemiologist, another important piece of the puzzle was that 70% of the ill individuals had eaten at Genki Sushi, but only around 22% of those of the public who had replied to a department survey had, a relationship that had not been seen for any other restaurant, food chain, or grocery store. Investigators had also been narrowing their search to items that are kept for a while, such as frozen or dried foods.

Once this shipment of scallops was believed to be the source, samples were sent to FDA for testing. Two days ago, FDA laboratory tests on two samples tested positive for the virus, and the next day, the company began a voluntary recall of their product. The scallops were also distributed to California and Nevada, and a recall is in effect. Since the scallops were not sold directly to the public, consumers of scallops are being encouraged to ask restaurants or retailers where their scallops come from. The product has also been embargoed by the state of Hawaii, meaning it cannot be sold, purchased, or consumed in Hawaii.

The first case in this outbreak was seen June 12, and currently 206 adults have been confirmed to have the disease, with 51 of these needing hospitalization for treatment.  Most of the cases live on Oahu, but some live on Hawaii, Kauai, and Maui. Some of these people are employed in food service and other service industries, but according to health officials, there was no indication their workplaces were sources of the outbreak, and the likelihood that patrons would contract the virus from these locations is believed to be low.

Moving forward, it is hoped that the recall will protect consumers, vaccines are being administered widely in the islands, and other U.S. health agencies have been notified to consider travel history to Hawaii if their patients report symptoms of hepatitis A.

 

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