Listeria account for less than 1 percent of reported cases of bacterial foodborne infection. Most identified cases can be traced back to contaminated food and the attack rate can be 50-100%. The lucky victims have subclinical infections.
Common symptoms include fever, watery diarrhea, nausea, vomiting, headache, and pains in joints and muscles.The typical duration of symptoms is two days or less, and recovery is generally complete. Invasive infection seems to be rare, with the risk being greatest in immunocompromised, pregnant, or older adult patients. Listerial infection in pregnant women can lead to fetal death, premature birth, or infected newborns.
The following represents a compilation of the precautions recommended by the Centers for Disease Control and Prevention:
●Do not drink raw (unpasteurized) milk or eat foods that contain unpasteurized milk.
●Wash raw vegetables thoroughly before eating.
●Keep the refrigerator temperature at 40ºF (4.4ºC) or lower; the freezer at 0ºF (-17.8ºC) or lower.
●Eat precooked, perishable, or ready-to-eat food as soon as possible.
●Keep raw meat, fish, and poultry separate from other food that will not be cooked and from cooked foods and ready-to-eat foods.
●Wash hands, knives, and cutting boards after handling uncooked food.
●Thoroughly cook raw food from animal sources to a safe internal temperature: ground beef 160ºF (71ºC), chicken 170ºF (77ºC), turkey 180ºF (82ºC), and pork 160ºF (71ºC).
The following additional recommendations were made for individuals at high risk such as pregnant women and those who are immunocompromised:
●Do not eat hot dogs, luncheon meats, bologna, or other delicatessen meats unless they are reheated until steaming hot; avoid the use of microwave ovens for reheating such meats since uneven cooking may occur.
●Avoid contamination of utensils and food preparation surfaces with fluid from packages containing hot dogs, luncheon meats, delicatessen meats, raw meat, chicken, turkey, or seafood. Handwashing is also important immediately after handling of any of these products.
●Do not eat prepackaged salads containing ham, chicken, egg, tuna, or seafood.
●Do not eat soft cheeses such as feta, Brie, and Camembert, blue-veined cheeses, or Mexican-style cheeses such as queso blanco, queso fresco, and Panela, unless they have labels that clearly state they are made from pasteurized milk.
●Do not eat refrigerated pâtés or meat spreads. However, canned or shelf-stable products are safe and can be eaten by pregnant women.
●Do not eat refrigerated smoked seafood, unless it is cooked as in a casserole. Refrigerated smoked seafood, such as salmon, trout, whitefish, cod, tuna, or mackerel, is most often labeled as "nova-style," "lox," "kippered," "smoked," or "jerky." Such fish products are typically found in the refrigerator section or sold at deli counters of grocery stores and delicatessens. However, canned or shelf-stable smoked seafood may be eaten.
The CDC has a comprehensive discussion.