CDC Report Links a Hepatitis A Outbreak to Frozen Blueberries

A newly published report in the CDC journal Emerging Infectious Diseases reconstructs a hepatitis A outbreak in the Netherlands that was linked to frozen blueberries. The article, published on July 14, 2026, is a retrospective investigation rather than a new blanket warning about frozen fruit. Its practical lesson is more specific: frozen foods can remain a food-safety concern when contamination occurs before they reach the freezer.

What the Dutch investigation found

The report covers 24 people who became ill between November 2024 and February 2025. All belonged to a hepatitis A virus genotype IA cluster. Patients ranged from 16 to 77 years old, with a median age of 41. Eight people were admitted to hospital, and no deaths were reported.

Investigators combined patient interviews, molecular surveillance and food testing. Of the 24 patients, one could not provide food-consumption information and another was considered likely to have been infected through contact with another patient. The remaining 22 had eaten a specific frozen-fruit brand bought from the same supermarket chain. Nineteen reported eating frozen blueberries, and 14 identified a particular package. Three others reported eating bilberries, blackberries or a mixed fruit product that also contained blueberries.

The strongest evidence came from leftover food. Inspectors collected packages from four patients’ homes and divided the contents into 66 laboratory subsamples. Hepatitis A virus RNA was found in all 10 subsamples taken from two opened packages containing only blueberries. The recovered viral sequences matched the outbreak strain over the full length of the fragments tested. No viral RNA was found in the other 56 subsamples, a result the researchers say is consistent with the uneven distribution and usually low levels of contamination that can make food testing difficult.

Why the evidence pointed to one batch

The two positive packages shared the same use-by date and had packing times close together. A third package with the same date but a later packing time tested negative. Investigators traced the suspected product to a single grower. The entire batch had been repacked into 1-kilogram bags for the supermarket chain and distributed to stores in southern parts of the Netherlands.

The combination of epidemiological and laboratory evidence led the retailer to recall the implicated batch, including earlier-date packages of the same size. The researchers also shared supplier information through the European Union’s Rapid Alert System for Food and Feed. They could not establish exactly where or when the initial contamination occurred. Possible routes discussed in the report include contaminated irrigation or washing water, manual harvesting and handling by people working in the supply chain.

Freezing does not make contaminated fruit safe

Frozen blueberries are convenient for smoothies, baking and quick desserts, but freezing is a storage method, not a guaranteed decontamination step. The Netherlands National Institute for Public Health and the Environment explains that hepatitis A virus can survive freezing temperatures long enough to infect people. The CDC report also identifies berries as a known risk product for foodborne viral disease, especially when they are eaten without prior heating.

That does not mean all frozen blueberries are unsafe. It does mean that consumers should treat frozen fruit as a ready-to-eat ingredient when a product is used without cooking. A clean-looking bag is not proof that a product is free of microscopic contamination, and washing cannot be relied upon to remove a virus once it is present throughout a food product.

What home cooks should do

Check current food-recall notices in the country where you shop. If a specific frozen-fruit product or lot is recalled, do not taste it or use it in smoothies, desserts or cooked dishes unless the authority’s instructions explicitly say otherwise.
Keep frozen fruit frozen until it is needed, and thaw it in the refrigerator when a recipe requires thawing. Avoid leaving opened bags on the counter while preparing other foods.
Wash hands with soap and water before handling frozen fruit and after touching packaging. Use clean utensils, containers and blender parts, and clean food-contact surfaces after preparation.
Do not assume that blending makes fruit safe. If an official notice recommends heating a product, follow the exact instructions in that notice rather than relying on a generic cooking time.

The Dutch public-health update says the 2025 recall concerned a specific 1-kilogram supermarket product and particular use-by dates, not all frozen fruit or all blueberries. It also reported that no further infections were expected after the relevant incubation period had passed. That distinction matters: the new CDC publication helps explain how the outbreak was investigated, but it is not a current general recall.

For anyone who may have eaten a product named in an active recall and later develops symptoms compatible with hepatitis A, such as unusual fatigue, fever, abdominal discomfort or jaundice, the safest step is to contact a healthcare professional and mention the possible food exposure. For everyday cooking, the broader takeaway is simple: frozen fruit still needs careful sourcing, clean handling and attention to official recall information.