Yamamoto Takehisa, Murai Kiyokazu, Hayama Yoko, Kobayashi Sota, Nagata Reiko, Kawaji Satoko, Osaki Makoto, Sakakibara Shin-Ichi, Tsutsui Toshiyuki
Epidemiology Unit, Division of Viral Disease and Epidemiology, National Institute of Animal Health, National Agriculture and Food Research Organization, Kannondai 3-1-5, Tsukuba, Ibaraki, 305-0856, Japan.
Epidemiology Unit, Division of Viral Disease and Epidemiology, National Institute of Animal Health, National Agriculture and Food Research Organization, Kannondai 3-1-5, Tsukuba, Ibaraki, 305-0856, Japan.
Prev Vet Med. 2018 Jan 1;149:38-46. doi: 10.1016/j.prevetmed.2017.10.009. Epub 2017 Nov 11.
Paratuberculosis or Johne's disease (JD), is a chronic infectious disease causing intractable diarrhea in cattle, which leads to less productivity, such as decreased milk yield, and lower daily weight gain. As a control measure against JD in cattle, national serological surveillance has been conducted in Japan since 1998. To conduct modeling studies that are useful to evaluate the effectiveness of control measures against JD, reliable parameter values, such as length of time from infection to the start of fecal shedding or antibody expression, are especially important. These parameters in the Japanese cattle population are assumed to be different from those in other countries with a higher prevalence of JD or in experimental infection settings; therefore, they must be estimated for the cattle population in Japan. Data from national surveillance conducted in Tokachi District, Hokkaido Prefecture, were used for this study. Using data from JD diagnostic tests for all cattle in Tokachi District between 1998 and 2014, all testing histories for infected animals were estimated as the number of tested cattle and positive cattle at each age of month for both fecal and antibody tests. A deterministic mathematical model for JD development, from infection to fecal shedding and antibody expression in infected cattle, was constructed to obtain the probability of testing positive when applied to both fecal and antibody tests at a given age. Likelihood was obtained from these estimated test results and best values for parameters were obtained using the Markov Chain Monte-Carlo method. Fifty-five percent of infected cattle were projected to have a transient shedding period, which was estimated to start 12 months after infection and last for 4 months. Persistent shedding was projected to occur in all infected cattle, and estimated to begin 7-84 months from infection. Following persistent shedding, antibody expression was estimated to start 7 months later. These values are useful for developing models to evaluate the status of JD infection and the effectiveness of control measures in the Japanese cattle population.
副结核病或约内氏病（JD）是一种导致牛顽固性腹泻的慢性传染病，会导致生产力下降，如产奶量减少和日增重降低。作为牛JD的防控措施，日本自1998年起开展了全国血清学监测。为进行有助于评估JD防控措施效果的模型研究，可靠的参数值，如从感染到开始粪便排菌或抗体表达的时间长度，尤为重要。日本牛群中的这些参数被认为与JD患病率较高的其他国家或实验感染环境中的参数不同；因此，必须针对日本的牛群进行估算。本研究使用了北海道十胜地区全国监测的数据。利用1998年至2014年十胜地区所有牛的JD诊断测试数据，估算了所有感染动物的检测历史，包括粪便和抗体检测在每个月龄时的检测牛数和阳性牛数。构建了一个从感染到感染牛粪便排菌和抗体表达的JD发展确定性数学模型，以获得在给定年龄应用于粪便和抗体检测时检测呈阳性的概率。从这些估算的检测结果中获得似然性，并使用马尔可夫链蒙特卡罗方法获得参数的最佳值。预计55%的感染牛有一个短暂排菌期，估计在感染后12个月开始，持续4个月。预计所有感染牛都会出现持续排菌，估计从感染后7 - 84个月开始。持续排菌后，估计7个月后开始出现抗体表达。这些值有助于建立模型，以评估日本牛群中JD感染状况和防控措施的效果。
