A hepatitis A outbreak linked to frozen berries has sickened almost 60 people in Germany across two years.

A total of 55 sequence-confirmed cases and four probable infections have been identified from 10 federal states, according to the Robert Koch Institut (RKI).

In January 2022, RKI was informed about eight hepatitis A virus (HAV) cases with identical genotype IB sequences from two federal states, Hesse and Bavaria. Because of a lack of travel history and the distribution of illnesses, transmission through contaminated food was suspected.

Based on initial surveys by health authorities and experience from past outbreaks, the hypothesis was that cases could be related to eating contaminated frozen berries. Because of the long shelf life and high stability of HAV, frozen products can still lead to illnesses months after purchase by the consumer.

Link to frozen strawberry products

There are 43 primary cases and 16 secondary cases with human-to-human transmission from a primary case. The first date of illness onset was in late October 2021, and the latest is from July 2023. A total of 42 people became ill since early 2023. Eight people fell sick in 2021 and nine in 2022.

Of 42 sequence-confirmed primary cases, 15 were male, and the median age was 30 and a half, ranging from 8 to 73 years old. Hospitalization was reported for 38 of 55 patients, but no deaths have been recorded.

Patients most frequently reported having frozen strawberries or products made from them. Consumption was probable for 25 of 39 people and possible for another seven patients.

Different retailers were mentioned as the place to purchase frozen strawberry products, but ten people named one supermarket.

“The results provide clear epidemiological evidence that frozen strawberries commercially available in Germany will likely be an important vehicle of infection in this outbreak. Based on results from the survey of those affected, it can be assumed that contaminated frozen strawberries were/are on sale nationwide under different brands and product names in different markets,” said scientists.

The Federal Office of Consumer Protection and Food Safety (BVL) has also shared the HAV sequence in the European disease surveillance system EpiPulse.

About Hepatitis A
Hepatitis A is a viral infection of the liver. Symptoms include loss of appetite, nausea, fever, and stomach pains, dark urine, pale stools, and jaundice. Handwashing and good hygiene practices are important to prevent transmission and vaccination.

The incubation period is 15 to 50 days, with an average of 28 days. The virus is spread by the fecal-oral route, usually by consuming contaminated food or water or through contaminated hands or objects. People are infectious from two weeks before symptom onset until one week after the onset of jaundice or dark urine. This means they may transmit the infection before knowing they are infected.

The illness is usually mild and lasts one to three weeks. Most people recover, but hepatitis A can lead to hospitalization and severe illness, particularly in people with chronic liver disease. Young children who are infected usually have few or no symptoms but can still transmit infection to others. Officials also tell people not to go to work if they have symptoms consistent with hepatitis A infection, mainly if they are food handlers, childcare workers, or healthcare employees.

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