Dubey J P, Hill D E, Jones J L, Hightower A W, Kirkland E, Roberts J M, Marcet P L, Lehmann T, Vianna M C B, Miska K, Sreekumar C, Kwok O C H, Shen S K, Gamble H R
United States Department of Agriculture, Agricultural Research Service, Animal and Natural Resources Institute, Animal Parasitic Diseases Laboratory, Beltsville, Maryland 20705-2350, USA.
J Parasitol. 2005 Oct;91(5):1082-93. doi: 10.1645/GE-683.1.
The prevalence of viable Toxoplasma gondii was determined in 6,282 samples (2,094 each of beef, chicken, and pork) obtained from 698 retail meat stores from 28 major geographic areas of the United States. Each sample consisted of a minimum of 1 kg of meat purchased from the retail meat case. To detect viable T. gondii, meat samples were fed to T. gondii-free cats and feces of cats were examined for oocyst shedding. Initially, 100 g of meat from 6 individual samples of a given species were pooled (total, 600 g), fed to a cat over a period of 3 days, and feces were examined for oocysts for 14 days; the remaining meat samples were stored at 4 C for 14 days (until results of the initial cat fecal examination were known). When a cat fed pooled samples had shed oocysts, 6 individual meat samples from each pool were bioassayed for T. gondii in cats and mice. Toxoplasma gondii isolates were then genetically characterized using the SAG2 locus and 5 hypervariable microsatellite loci. In all, 7 cats fed pooled pork samples shed oocysts. Toxoplasma gondii oocysts were detected microscopically in the feces of 2 of the cats; 1 isolate was Type II and the second was Type III. Analyzed individually, T. gondii was detected by bioassay in 3 of the 12 associated samples with genetic data indicating T. gondii isolates present in 2. The remaining 5 pooled pork samples had so few oocysts that they were not initially detected by microscopic examination, but rather by mouse bioassay of cat feces. Two were Type I, 1 was Type II, and 2 were Type III. None of the cats fed chicken or beef samples shed oocysts. Overall, the prevalence of viable T. gondii in retail meat was very low. Nevertheless, consumers, especially pregnant women, should be aware that they can acquire T. gondii infection from ingestion of undercooked meat, and in particular, pork. Cooking meat to an internal temperature of 66 C kills T. gondii.
在美国28个主要地理区域的698家零售肉店采集了6282份样本（牛肉、鸡肉和猪肉各2094份），测定其中活的刚地弓形虫的流行情况。每个样本至少包含从零售肉柜购买的1千克肉。为检测活的刚地弓形虫，将肉样喂给无刚地弓形虫的猫，并检查猫的粪便中是否有卵囊排出。最初，将给定物种的6个个体样本中的100克肉混合（共600克），在3天内喂给一只猫，并在14天内检查粪便中的卵囊；其余肉样在4℃下保存14天（直到最初的猫粪便检查结果出来）。当喂食混合样本的猫排出卵囊时，对每个样本池中的6个个体肉样进行猫和小鼠体内的刚地弓形虫生物测定。然后使用SAG2基因座和5个高变微卫星基因座对刚地弓形虫分离株进行基因特征分析。总共有7只喂食混合猪肉样本的猫排出了卵囊。在其中2只猫的粪便中通过显微镜检测到了刚地弓形虫卵囊；1株分离株为II型，另一株为III型。单独分析时，在12个相关样本中有3个通过生物测定检测到了刚地弓形虫，基因数据表明其中2个样本中有刚地弓形虫分离株。其余5个混合猪肉样本中的卵囊数量很少，最初未通过显微镜检查检测到，而是通过对猫粪便进行小鼠生物测定才检测到。其中2株为I型，1株为II型，2株为III型。喂食鸡肉或牛肉样本的猫均未排出卵囊。总体而言，零售肉中活的刚地弓形虫的流行率非常低。然而，消费者，尤其是孕妇，应该意识到他们可能因食用未煮熟的肉，特别是猪肉而感染刚地弓形虫。将肉煮至内部温度66℃可杀死刚地弓形虫。
