Listeriosis Update

CDC, state and local health departments, and the United States Department of Agriculture (USDA) Food Safety and Inspection Service (FSIS) have been investigating an outbreak of listeriosis, primarily affecting persons in the northeastern United States. Thus far, 50 ill persons infected with the outbreak strain of Listeria have been detected since mid-July; most were hospitalized, seven have died, and three pregnant women have had miscarriages or stillbirths. Epidemiologic data indicate that precooked, sliceable turkey deli meat is the cause of this outbreak.

As part of the outbreak investigation, USDA-FSIS obtained food and environmental samples from Pilgrim's Pride Corporation, located in Franconia, Pennsylvania. One food product and 25 environmental samples tested positive for Listeria. USDA-FSIS laboratories performed DNA fingerprinting on these bacteria. Comparison of different strains was conducted through PulseNet, which is a network of public health and regulatory laboratories that perform DNA fingerprinting of bacteria and electronically share results. The food product had a strain of Listeria different from the outbreak strain. Of the 25 environmental Listeria strains fingerprinted, 1 matched that of the food product and 2 matched that of patients in the current outbreak. On October 12, the plant voluntarily shut down operations and issued a recall of approximately 27 million pounds of fresh and frozen ready-to-eat turkey and chicken products produced since May 1, 2002. Turkey meat products included in the recall should not be eaten. Information on specific products and brands covered by the recall is available at: http://www.fsis.usda.gov/OA/recalls/prelease/pr090-2002.htm.

Listeriosis is a serious foodborne disease that can be life-threatening to certain individuals, including the elderly or those with weakened immune systems. It can also cause miscarriages and stillbirths in pregnant women. The affected patients live in 8 states: Pennsylvania (14 cases), New York (11 cases in New York City, 9 in other locations), New Jersey (5 cases), Delaware (4 cases), Maryland (2 cases), Connecticut (1 case), Michigan (1 case), and Massachusetts (3 cases). Thirty-one patients were male and 19 were female. Sixteen patients were age 65 or above, 14 patients were age 1 to 64 years and had an immunocompromising medical condition, eight others were pregnant, and three were neonates; seven patients were age 1 to 64 years and were not pregnant or known to have an immunocompromising condition. No medical information was available for two patients. Of the seven patients who died, six had immunocompromising conditions (three of these patients were also age 65 or older), and one was a neonate. The most recent patient became ill on October 9.

In addition to the patients whose illnesses have been confirmed as part of the outbreak, CDC and state and local health departments have learned about other cases of Listeria infection in the same region during the outbreak time period. DNA fingerprinting has shown that strains from 81 patients in these same states are different from the outbreak strain and 20 of these patients have died; these illnesses are part of the "background" of sporadic Listeria infections and are likely due to a variety of different foods. In addition, testing of strains from several additional persons is ongoing; some of these may be identified as the outbreak strain. Because pregnant women, older adults, and people with weakened immune systems are at higher risk for listeriosis, we recommend the following measures for those persons:

Do not eat hot dogs and luncheon meats, unless they are reheated until steaming hot.

Avoid cross-contaminating other foods, utensils, and food preparation surfaces with fluid from hot dog packages, and wash hands after handling hot dogs.

Do not eat soft cheeses such as Feta, Brie and Camembert cheeses, blue-veined cheeses, and Mexican-style cheeses such as "queso blanco fresco." Cheeses that may be eaten include hard cheeses; semi-soft cheeses such as mozzarella; pasteurized processed cheeses such as slices and spreads; cream cheese; and cottage cheese.

Do not eat refrigerated pâtés or meat spreads. Canned or shelf-stable pâtés and meat spreads may be eaten.

Do not eat refrigerated smoked seafood, unless it is contained in a cooked dish, such as 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." The fish is found in the refrigerator section or sold at deli counters of grocery stores and delicatessens. Canned or shelf-stable smoked seafood may be eaten.

Do not drink raw (unpasteurized) milk or eat foods that contain unpasteurized milk.

About 2500 cases of listeriosis occur each year in the United States. The initial symptoms are often fever, muscle aches, and sometimes gastrointestinal symptoms such as nausea or diarrhea. The illness may be mild and ill persons sometimes describe their illness as flu-like. If infection spreads to the nervous system, symptoms such as headache, stiff neck, confusion, loss of balance, or convulsions can occur. Most cases of listeriosis and most deaths occur in adults with weakened immune systems, the elderly, pregnant women, and newborns. However, infections can occur occasionally in otherwise healthy persons. Infections during pregnancy can lead to miscarriages, stillbirths, and infection of newborn infants. Previous outbreaks of listeriosis have been linked to a variety of foods especially processed meats (such as hot dogs, deli meats, and paté) and dairy products made from unpasteurized milk.

The risk of an individual person developing Listeria infection after consumption of a contaminated product is very small. If you have eaten a contaminated product and do not have any symptoms, we do not recommend that you have any tests or treatment, even if you are in a high risk group. However, if you are in a high risk group, have eaten the contaminated product, and within a month become ill with fever or signs of serious illness, you should contact your health care provider and inform him or her about this exposure.

If you have questions about Listeria, you can call your local or state health department, your physician, or visit the CDC web site at http://www.cdc.gov/ncidod/dbmd/diseaseinfo/listeriosis_g.htm or visit the USDA web site at http://www.usda.gov/news/releases/2001/01/0020.htm.

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