Federal officials are collecting 2,000 samples of frozen berries produced in and imported to the United States as part of an effort to develop preventive controls against pathogens such as hepatitis A and norovirus.

The two viruses caused outbreaks in recent years that sickened hundreds of people across the United States. In some outbreaks retailers sold contaminated berries directly to consumers. In other instances, domestic entities bought imported berries in bulk and used them as ingredients in their products.

Berries are served raw alone and in various recipes, making them more dangerous in terms of foodborne pathogens than many other domestic and imported foods, according to an announcement today from the Food and Drug Administration.

The agency reported that the testing program began in November 2018. Results will be posted for public view on a quarterly basis during the “sampling assignment,” which will likely take about 18 months to complete. A final analysis is planned after the data is reviewed.