Update: Listeriosis Outbreak Investigation

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, 53 ill persons infected with the outbreak strain of Listeria have been identified since mid-July; most were hospitalized, eight 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 ongoing outbreak investigation, USDA-FSIS has been investigating turkey processing plants. Listeria bacteria have been found in turkey products and environmental samples from two plants. USDA-FSIS laboratories performed DNA fingerprinting on these bacteria. Comparison of strains was conducted through PulseNet, a network of public health and regulatory laboratories coordinated by CDC that perform DNA fingerprinting of bacteria and electronically share results.

From Pilgrim's Pride Corporation, located in Franconia, Pennsylvania, two ready-to-eat turkey products and 25 environmental samples tested positive for Listeria. The turkey products had strains of Listeria different from the outbreak strain. Of the 25 environmental Listeria strains fingerprinted, two were indistinguishable from the strain of patients in the current outbreak and several were indistinguishable from strains found in the turkey products. 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. The plant resumed operations on November 13, 2002.

From Jack Lambersky Poultry Company, located in Camden, New Jersey, some ready-to-eat poultry products were contaminated with a strain of Listeria that is indistinguishable from that of the outbreak patients. In addition, one environmental sample from the plant tested positive for a strain of Listeria different from the outbreak strain. On November 2, the plant voluntarily suspended operations and recalled approximately 200,000 pounds of fresh and frozen ready-to-eat poultry products. The plant subsequently resumed operations on November 14, 2002. On November 20, the plant voluntarily expanded the recall after an additional poultry product tested positive for Listeria monocytogenes; DNA fingerprinting of this strain is underway. An additional ~4.2 million pounds of fresh and frozen, ready-to-eat poultry products produced between May 29 and November 2 were recalled.

Turkey meat products included in these recalls should not be eaten. Information on specific products and brands covered by the recalls is available at:

http://www.fsis.usda.gov/OA/recalls/prelease/pr090-2002.htm

http://www.fsis.usda.gov/OA/recalls/prelease/pr098-2002.htm

http://www.fsis.usda.gov/oa/recalls/prelease/pr098-2002exp_products.htm.

On November 18, USDA released a draft administrative directive outlining additional measures to be taken by USDA inspectors to ensure that establishments producing ready-to-eat meat and poultry products are taking the necessary steps to prevent contamination with Listeria monocytogenes. Information about the draft directive can be found at:

http://www.usda.gov/news/releases/2002/11/0478.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 9 states: Pennsylvania (15 cases), New York (12 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), Massachusetts (3 cases), and Illinois (1 case). Thirty-two patients were male and 21 were female. Sixteen patients were age 65 or above, 17 patients were age 1 to 64 years and had an immunocompromising medical condition, eight others were pregnant, and four 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 one patient. Of the eight patients who died, seven had immunocompromising conditions (three of these patients were also age 65 or older), and one was a neonate. The culture date for the most recent patient was October 26. 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 98 patients in these same states are different from the outbreak strain and 24 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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