Food contaminated with Listeria monocytogenes bacteria can cause a severe, often fatal, infection called listeriosis. Pregnant women, older people and people with compromised immune systems are most at risk. Among pregnant women, Listeria can cause miscarriage and stillbirth.
Foods That Have Caused Listeria Outbreaks
- Soft cheese including Panela, Queso Fresco, Requeson, Cotija, blu-veined, Feta, Brie and Camembert.
- Raw milk (unpasteurized) or products made with raw milk including the soft cheeses listed above, and hard cheeses such as Gouda, Swiss and cheddar.
- Cantaloupe (2011 outbreak was one of the deadliest food poisoning outbreaks in U.S. history)
- Apple slices and prepackaged caramel apples
- Ice cream
- Deli meat such as ham, turkey, salami, prosciutto and mortadella
- Refrigerated pâtés or meat spreads
- Smoked salmon
- Frozen vegetables, entrees and snack foods
How Does Listeria Contaminate Food?
Listeria bacteria are found naturally in the soil and in the intestinal tracts of some animals, including poultry and cattle. Unlike other foodborne pathogens, Listeria can grow in cold temperatures and is not killed by freezing. The only way to kill Listeria is to heat it to a temperature of 165˚F.
Fruits and vegetables can become contaminated during the growing process if they come into contact with soil or manure (used as fertilizer) that contains Listeria. They also can become contaminated during processing if the facility isn’t sanitary. For example, inspectors of the plant linked to the cantaloupe outbreak found Listeria in standing water under the equipment used to wash the melons.
Dairy products can get contaminated from cattle feces containing the bacteria. If the milk isn’t pasteurized (heated to kill the pathogens), the milk, cheese, or other dairy products made from it can cause illness.
Pasteurized ice cream can become contaminated from added ingredients such as fresh fruits, berries or nuts. It can also become tainted if it is manufactured in a facility that has unsanitary conditions.
- Hotdogs, deli meats, smoked salmon, pâtés and frozen processed foods can get contaminated in processing plants that are unsanitary.
- Whether it’s clover sprouts or caramel apples, it’s the responsibility of companies that produce food to keep their facilities and equipment clean and to prevent bacterial contamination of their products.