畢業(yè)設計(論文)外文參考資料及譯文-腸出血性大腸桿菌-展示頁
2025-01-21 21:28本頁面
【正文】 he United States). Sixtythree to 85% of cases are a result of exposure to the pathogen through food. The percentage of EHEC infections which progress to HUS varies between sporadic cases (3%7%) and those associated with outbreaks (20% or more). In epidemiological terms, there is generally a background of sporadic cases, with occasional outbreaks. Some of these outbreaks have involved a high number of cases, such as in Japan in 1996, where an outbreak linked to contaminated radish sprouts in school lunches caused 9 451 cases. Data on the situation in developing countries are limited, as surveillance for this pathogen is not done routinely. Sources of infection Most available information relates to serotype O157:H7, since it is easily differentiated biochemically from other E. coli strains. The reservoir of this pathogen appears to be mainly cattle and other ruminants such as camels. It is transmitted to humans primarily through consumption of contaminated foods, such as raw or undercooked ground meat products and raw milk. Faecal contamination of water and other foods, as well as crosscontamination during food preparation (with beef and other meat products, contaminated surfaces and kitchen utensils), will also lead to infection. Examples of foods implicated in outbreaks of E. coli O157:H7 include undercooked hamburgers, dried cured salami, unpasteurized freshpressed apple cider, yogurt, cheese and milk. An increasing number of outbreaks are associated with the consumption of fruits and vegetables (sprouts, lettuce, coleslaw, salad) whereby contamination may be due to contact with faeces from domestic or wild animals at some stage during cultivation or handling. EHEC has also been isolated from bodies of water (ponds, streams), wells and water troughs, and has been found to survive for months in manure and watertrough sediments. Waterborne transmission has been reported, both from contaminated drinkingwater and from recreational waters. Persontoperson contact is an important mode of transmission through the oralfaecal route. An asymptomatic carrier state has been reported, where individuals show no clinical signs of disease but are capable of infecting others. The duration of excretion of EHEC is about one week or less in adults, but can be longer in children. Visiting farms and ot
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