Risk Assessment of the Public Health Impact of Foodborne Listeria monocytogenes

The microbial pathogen, Listeria monocytogenes,is widespread in the agricultural and food processing plant environment and frequently is present in many foods. The organism can also be found in the gastrointestinal tract of some healthy adults. Despite the pervasive prevalence of the bacteria, the rate of listeriosis is not high. The disease, however, is serious when it occurs, causing meningitis in immunocompromised individuals and stillbirths and abortions in pregnant women. <P> Our risk assessment will determine whether certain foods contribute a significant portion of the total ingestion of this pathogen, what the consumption levels are, and what numbers of L. monocygtogenes cause illness in different people. Exposure assessment will determine the frequencies of occurrences and numbers in different classes of foods, particularly the ready-to-eat foods. When combined with food consumption data bases, the major sources of dietary L. monocytogenes will be identified. Epidemiological evidence of the foods causing both documented outbreaks and sporadic cases, the pathogen numbers consumed, the populations which become ill, and the severity of illness will be collected. This evidence will be supported by in vivo and in vitro experimental information. Evaluation of the dose-response relationship will include the health effects from consuming specific numbers of L. monocytogenes by individuals with different immune states and factors from the food matrix and characteristics of specific strains that affect illness.
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This risk assessment will provide the scientific information for the development of policies to create effective agency programs and minimize the public health impact of this pathogen. This risk assessment is the initial activity necessary for FDA and FSIS to review their regulatory programs.