In Aug. 2010, Veron Foods, LLC of Prairieville, La. recalled approximately 500,000 pounds of “ready to eat” sausage and hog head cheese products that ‘may have been’ contaminated with Listeria monocytogenes.

The problem was discovered through a foodborne illness investigation that resulted in a product sample testing positive for Listeria monocytogenes, but, like crappy food safety agencies here and there, the Louisiana types wouldn’t say how many got sick.

And everyone went back to sleep.

Until today, when the U.S. Centers for Disease Control issued its report about an outbreak of listeria associated with eating hog head cheese in Louisiana in 2010.

I’m guessing it was the same outbreak.

During January–June 2010, a total of 14 cases of laboratory-confirmed invasive listeriosis were reported to the Louisiana Office of Public Health (OPH). Isolates of Listeria monocytogenes from the blood samples of eight patients were identified as serotype 1/2a and had pulsed-field gel electrophoresis (PFGE) pattern combinations that were indistinguishable from one another. …

In-depth epidemiologic and environmental investigations of the cluster were initiated on July 26, including food history interviews of four patients. Three patients reported eating hog head cheese (a meat jelly made from swine heads and feet); the product was purchased at two grocery stores in Louisiana. A traceback investigation determined that a single brand of hog head cheese was common between the two grocery stores. L. monocytogenes serotype 1/2a was cultured from one of three product samples and from two of 16 environmental samples collected by LDAF at the processing establishment; the product and one of the two environmental samples yielded isolates with PFGE pattern combinations that were indistinguishable from the patient isolates. On August 14, LDAF coordinated a voluntary recall of approximately 500,000 pounds of hog head cheese and sausage because of possible contamination with L. monocytogenes.

This is the first published report of an invasive listeriosis outbreak associated with hog head cheese, which is a ready-to-eat (RTE) meat. USDA-FSIS has a "zero tolerance" policy for L. monocytogenes contamination of RTE food products (1), requesting recall of such products at any detectable level of L. monocytogenes contamination. LDAF imposes and enforces equivalent requirements in state-inspected establishments.

Louisiana OPH epidemiologists noted that 14 cases of invasive listeriosis had been reported during January–June 2010, which exceeded the state’s average of five cases reported during each January–June period during the previous 3 years. For this investigation, a cluster-associated case was defined as isolation of L. monocytogenes serotype 1/2a from a normally sterile site (e.g., blood or cerebrospinal fluid) or from placental or fetal tissue (in the setting of miscarriage or stillbirth) since January 1, 2010, and PFGE pattern combination GX6A16.0001 and GX6A12.0001.

Eight patients had illnesses that met the case definition. Their median age was 64 years (range: 38–93 years). Six patients were men; no patients were pregnant. Six patients had one or more underlying medical conditions (i.e., human immunodeficiency virus [HIV] infection, alcohol abuse, cancer, and diabetes mellitus). Illness onsets occurred from February 18 to June 16. Signs and symptoms included fever (n = 6 patients), altered mental status (n = 3), diarrhea (n = 3), vomiting (n = 3), and weakness (n = 2). Seven patients were hospitalized; two patients died. …

The implicated brand of hog head cheese originated from a small, state-inspected processing establishment in Louisiana, which produces approximately 600 pounds of hog head cheese per week. This establishment was under federal inspection until January 2007. Routine FSIS microbiologic testing of products at the establishment detected L. monocytogenes contamination in October and December 2006; the company voluntarily recalled 290 pounds of hog head cheese in January 2007. Four L. monocytogenes isolates from USDA-FSIS samples collected in 2006 did not match the 2010 outbreak-related PFGE pattern combination. In addition, Listeria contamination was not detected in any of the 12 product samples collected by LDAF since 2007; analysis of routine environmental samples collected by the management of the processing establishment during January–July 2010 also did not detect Listeria. However, the outbreak strain was identified in environmental samples collected during the investigation, which was several weeks after the manufacture of the outbreak-associated products (Figure), suggesting that persistent environmental contamination in the processing establishment was responsible for product contamination and resulting illnesses.