Hitchins A D
Division of Microbiological Studies (HFS-516), Food and Drug Administration, Washington, DC 20204, USA.
Int J Food Microbiol. 1996 Jun;30(1-2):71-85. doi: 10.1016/0168-1605(96)00992-0.
Survey data on the frequency of foodborne occurrence and dietary exposure to Listeria monocytogenes were used to estimate the mininmal mean per person annual rate of exposure in the United States during the late 1980s. The estimate was restricted to ready-to-eat (RTE) foods because proper cooking was assumed to be listericidal. The mean amount of each food type per L. monocytogenes occurrence was calculated in about 100 sources, and dietary intake data were used to calculate the mean number of occurrences of L. monocytogenes consumption per person per year. The mean number of occurrences consumed annually per person was determined to be 10 to 100 for RTE food values of 2 to 20% of the total dietary intake, respectively. The frequency of foodborne listeriosis (approximately 10(-5)) was consistent with the estimated exposure rate only if the susceptible population was unexpectedly small or extremely high doses were necessary for infection. Because little evidence is available to support a high rate of unreported non-severe infections, this study was concerned only with severe listeriosis cases. Published frequencies of L. monocytogenes concentrations in food were used to convert occurrences to colony forming units (CFU). Low L. monocytogenes concentrations (approximately 1 CFU/g) were too frequent to be responsible for listeriosis in susceptible subjects, would have caused listeriosis only with extremely low probability in a one-cell threshold infection model. The probability of exposure to a higher dose (> or = 10(3) CFU) was large enough to account for the observed rate of listeriosis.
关于食源性李斯特菌病发生频率和饮食中单核细胞增生李斯特菌暴露情况的调查数据，被用于估算20世纪80年代末美国人均每年的最低平均暴露率。该估算仅限于即食（RTE）食品，因为假定适当烹饪可杀灭李斯特菌。在约100个来源中计算了每种食品类型每次单核细胞增生李斯特菌出现时的平均含量，并使用饮食摄入数据计算每人每年食用单核细胞增生李斯特菌的平均出现次数。对于占总饮食摄入量2%至20%的即食食品，确定每人每年食用的平均出现次数分别为10至100次。仅当易感人群意外较少或感染需要极高剂量时，食源性李斯特菌病的发生频率（约10^(-5)）才与估计的暴露率一致。由于几乎没有证据支持未报告的非严重感染率很高，本研究仅关注严重李斯特菌病病例。已发表的食品中单核细胞增生李斯特菌浓度频率被用于将出现次数转换为菌落形成单位（CFU）。低浓度的单核细胞增生李斯特菌（约1 CFU/g）出现过于频繁，不可能是易感人群中李斯特菌病的病因；在单细胞阈值感染模型中，只有极低概率会引发李斯特菌病。接触较高剂量（≥10³ CFU）的概率足够大，足以解释观察到的李斯特菌病发生率。
