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Background Despite a decreasing incidence of listeriosis in the United States, molecular subtyping has increased the number of recognized outbreaks. In September 2000, the New York City Department of Health identified a cluster of infections caused by Listeria monocytogenes isolates with identical molecular subtypes by pulsed-field gel electrophoresis (PFGE) and ribotyping. Methods To determine the magnitude of the outbreak and identify risk factors for infection, we notified state health departments and conducted a case-control study. A case was defined as a patient or mother-infant pair infected with Listeria monocytogenes whose isolate yielded the outbreak PFGE pattern. Controls were patients infected with Listeria monocytogenes whose isolate yielded a different PFGE pattern. Patients were asked about food and drink consumed during the 30 days before the onset of illness. Results Between May and December 2000, there were 30 clinical isolates of Listeria monocytogenes with identical PFGE patterns identified in 11 US states. Cases of infection caused by these isolates were associated with 4 deaths and 3 miscarriages. A case-control study implicated sliced processed turkey from a delicatessen (Mantel-Haenszel odds ratio, 8.0; 95% confidence interval, 1.2-43.3). A traceback investigation identified a single processing plant as the likely source of the outbreak, and the company voluntarily recalled 16 million pounds of processed meat. The same plant had been identified in a Listeria contamination event that had occurred more than a decade previously. Conclusions Prevention of persistent L. monocytogenes contamination in food processing plants presents a critical challenge to food safety professionals.

Background Creutzfeldt-Jakob disease (CJD) in humans and chronic wasting disease (CWD) in deer and elk occur in the United States. Recent reports of 3 unusually young patients with CJD who regularly consumed deer or elk meat created concern about the possible zoonotic transmission of CWD. Objective To examine the possible transmission of CWD to humans. Patients Three unusually young patients (aged 28, 28, and 30 years) with CJD in the United States during 1997-2000. Methods We reviewed medical records and interviewed family members and state wildlife and agriculture officials. Brain tissue samples were tested using histopathologic, immunohistochemical, immunoblot, or prion protein gene analyses. Main Outcome Measures Presence or absence of established CJD risk factors, deer and elk hunting in CWD-endemic areas, and comparison of the evidence for the 3 patients with that of a zoonotic link between new variant CJD and bovine spongiform encephalopathy. Results None of the patients had established CJD risk factors or a history of travel to Europe. Two patients hunted game animals and 1 was a daughter of a hunter. Unlike patients with new variant CJD, the 3 patients did not have a unique neuropathologic manifestation, clinicopathologic homogeneity, uniformity in the codon 129 of the prion protein gene, or prion characteristics different from those of classic variants. Conclusions Although the occurrence of 3 unusually young patients with CJD who consumed venison suggested a possible relationship with CWD, our follow-up investigation found no strong evidence for a causal link. Ongoing CJD surveillance remains important for continuing to assess the risk, if any, of CWD transmission to humans.