贵州省安顺市一起牛传染性支原体肺炎的暴发调查

An Outbreak Investigation on Infectious Mycoplasma Bovis Pneumonia in Anshun City of Guizhou Province

2019年9月30日至10月12日,安顺市某养牛场饲养的牛陆续出现反复发热、咳嗽、关节肿胀等病症,并有少量犊牛死亡。为找出可能的病因,通过现场调查,了解养殖场养殖与管理情况、发病死亡情况、用药治疗情况等,并采集血液样本和鼻腔棉拭子进行实验室检测;采用描述性研究,描述疫情的三间分布;通过IBM SPSS Statistics 25统计软件,计算不同群间的相对发病风险(RR),分析发病风险因素。本次疫情的犊牛袭击率为100%,病死率为7.5%;育肥牛袭击率为82.0%,能繁母牛袭击率为22.5%,种公牛袭击率为20.0%;犊牛发病风险是育肥牛的1.2倍(95%CI:1.1~1.3),是能繁母牛的4.4倍(95%CI:2.5~7.9),育肥牛的发病风险是能繁母牛的3.6倍(95%CI:2.0~6.5)。结合现场调查和实验室检测结果,判定这是一起因外购犊牛管理不善、产生应激反应而引发的养牛场牛传染性支原体肺炎暴发事件。采用针对性的药物,如氟苯尼考、地塞米松、环丙沙星等治疗后,病情得到有效控制。疫情提示,场主需规范场内饲养管理,减少应激因素产生,提高牛群抗病能力,以降低此类疫情发生的风险。

On September 30 to October 12,2019,a large number of cattle in a farm in Anshun City of Guizhou Province continuously suffered from recurrent fever,cough,joint swelling and other symptoms,and a few calves died.In order to find out the possible etiological factors,a field investigation was carried out,and the breeding and management of the farm,morbidity and mortality,medication and other factors were investigated,then blood samples and nasal swabs were collected for laboratory testing;the distributions of time,regions and populations of the outbreak was described through descriptive study;the relative risk(RR)among different populations was calculated by the statistical software of IBM SPSS Statistics 25 to analyze relevant risk factors.According to the analysis,the attack rate for calves was 100%,with the mortality rate of 7.5%;the attack rates for fattening cattle,reproductive cows and breeding oxen were 82.0%,22.5%and 20.0%respectively;the incidence risk of calves was 1.2 times that of fattening cattle(95%CI:1.1–1.3)and 4.4 times that of reproductive cows(95%CI:2.5–7.9),and the incidence risk of fattening cattle was 3.6 times than that of reproductive cows(95%CI:2.0–6.5).Finally,it was determined that it was an outbreak of infectious Mycoplasma bovis pneumonia caused by stress reaction of purchased calves due to the poor management according to the results of field investigation and laboratory testing.The outbreak was effectively controlled by treatment with targeted drugs,including Florfenicol,Dexamethasone and Ciprofloxacin,etc.Therefore,it was suggested that the level of feeding management in farms should be standardized by their owners to reduce any possible stress reaction and to improve the disease resistance of cattle,so as to reduce any outbreak risk of such disease.