Outbreaks of Foodborne Illness Associated with Common Berries, 1983 through May 2013
Fresh and frozen common berries (i.e., blackberries, blueberries, raspberries, and strawberries) are popular and healthy foods. When berries are picked for fresh consumption, they are either placed directly in retail containers in the field or packed in a packinghouse without washing because they are highly perishable. Berries may be washed before freezing, but they are not usually blanched or heattreated unless they are used in preserves or other processed products. Thus, there is typically no “kill step” that would eliminate pathogens in fresh or frozen berries.
Berries may be served mixed with other foods such as in salads or desserts, and these may contain more than one kind of berry or other fruit. Epidemiologists have more difficulty accurately determining the food vehicle during a foodborne illness outbreak when the outbreak is associated with mixed foods, such as mixed berries. The viral and parasitic pathogens that have caused outbreaks associated with consumption of berries are difficult to detect in foods. The laboratory methods used to detect these pathogens have only recently been developed or are still under development.
This publication serves as a reference for anyone concerned about the safety of fresh and frozen berry products.