L. monocytogenes is hardy; it is salt-tolerant and not only can survive in temperatures below 1°C, but also grow in these conditions, unlike many other pathogens. It is also notable for its persistence in food-manufacturing environments. The bacterium is ubiquitous in the environment and can be found in moist environments, soil, and decaying vegetation. Of the five other species in the genus Listeria – L. grayi, L. innocua. L. ivanovii, L. seeligeri and L. welshimeri – only L. ivanovii is considered pathogenic, and mainly in ruminants, rather than in humans. 2. Disease Mortality : Although not a leading cause of foodborne illness, L. monocytogenes is among the leading causes of death from foodborne illness. A recent report by the Centers for Disease Control and Prevention (CDC) estimated that domestically acquired foodborne L. monocytogenes causes 255 deaths in the U.S. annually. The severe form of the infection has a case-fatality rate of 15% to 30%, overall. When For Consumers: A Snapshot Although the number of people infected by foodborne Listeria is comparatively small, this bacterium is one of the leading causes of death from foodborne illness. It can cause two forms of disease. One can range from mild to intense symptoms of nausea, vomiting, aches, fever, and, sometimes, diarrhea, and usually goes away by itself. The other, more deadly form occurs when the infection spreads through the bloodstream to the nervous system (including the brain), resulting in meningitis and other potentially fatal problems. Pregnant women are more susceptible to Listeria infection than are most other people, and although they generally recover, their babies usually don’t survive. People with weak immune systems also are more vulnerable (for example, those with AIDS or chronic diseases, or who are on certain immune ‐ suppressing arthritis drugs or cancer chemotherapy). Because our immune systems weaken as we age, the elderly also are especially vulnerable to this pathogen. Listeria cases have been traced back to several foods; for example, raw or under ‐ pasteurized milk; smoked fish and other seafood; meats, including deli meats; cheeses (especially soft cheeses); and raw vegetables. Listeria is hardy; it tolerates salty environments and cold temperatures, unlike many other foodborne bacteria. You can help protect yourself from infection with Listeria by not drinking un pasteurized milk (also called "raw" milk) or certain cheeses or other foods made with raw milk; and by cooking food according to instructions; washing fruits and vegetables; keeping raw foods from touching other foods, dinnerware, kitchen counters, etc.; and washing your hands and other things that have come into contact with raw foods. listerial meningitis occurs, the case-fatality rate may be as high as 70%; from septicemia, 50%, overall; and in perinatal/neonatal infections, more than 80%.
Infective dose : The infective dose of L. monocytogenes is undetermined, but is believed to vary with the strain and susceptibility of the host, and the food matrix involved also may affect the dose-response relationship. In cases associated with raw or inadequately
You've reached the end of your free preview.
Want to read all 292 pages?
- Spring '12
- The Land, C. jejuni, Campylobacter jejuni, Y. enterocolitica, Bad Bug Book