Poorly cooked pork liver was the suspected source of a hepatitis E outbreak in China in 2022, according to a recent report.

In July and August 2022, an outbreak of hepatitis E was reported in a nursing home in Hangzhou, Zhejiang Province. 

A case-control study was conducted to identify risk factors for the outbreak. Of the 722 people in the nursing home, 77 were diagnosed with hepatitis E. The most affected group was carers, followed by people receiving care, and nurses. Among them, 18 had symptoms such as jaundice, fever, and loss of appetite.

The average age of people infected with hepatitis E virus (HEV) was almost 60 years old and 59 patients were women while 18 were men, according to the study published in the International Journal of Food Microbiology.

From July 31 to August 10, 2022, three cases of hepatitis E were reported in the nursing home and the local Center for Disease Control sent personnel to the site to verify the incident and conduct epidemiological investigations.

The first patient was a 59-year-old married female who was a caregiver at the nursing home. In late July 2022, she experienced symptoms including poor appetite, nausea, aversion to oily food, fatigue, yellow urine, and jaundice in the eyes. On July 31, she was diagnosed with hepatitis E at the hospital. The second patient was a 59-year-old married caregiver who developed poor appetite, yellow urine, and yellowing of the eyes on July 31. He was diagnosed with hepatitis E on August 2.

A case-control study showed that consuming pig liver and having raw fruits and vegetables provided by the cafeteria were risk factors for this outbreak.

Cooking time and poor practices
Researchers said the investigation found poor conditions in the nursing home canteen, and the cooking time of pork liver was too short. A monitoring video showed that canteen staff did not separate raw and cooked foods, and pig livers were cooked for only 2 minutes and 10 seconds. Other studies have showed that the inactivation time of HEV in liver at 71 degrees C (159.8 degrees F) is five minutes or longer.

Hygiene conditions of the canteen were poor, with cockroaches found onsite. Zoning was not strictly enforced, and there was a lack of separation between raw and cooked food. Although a steam pot was available to disinfect tableware, it was infrequently used.

As raw and cooked food were not adequately separated, this could lead to HEV contamination via the hands of cafeteria staff to fruits and vegetables, said researchers.

There were no leftover food samples in the canteen. Fresh samples of pig livers collected from suppliers tested negative for HEV.

Control measures included isolating and treating patients, conducting thorough cleaning and disinfection, and after the outbreak, vaccination for HEV was administered.

“Canteen personnel should be alerted about the importance of sufficient cooking time and temperature during stir-frying to ensure the inactivation of the HEV. Measures such as strengthening hygiene supervision in the food industry and recommending vaccination for high-risk groups are also necessary,” said scientists.

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