Winters J B, Worley D E
Am J Vet Res. 1975 Mar;36(3):327-9.
In a survey (Oct, 1967, through Aug, 1969) of the distribution and seasonal prevalence of bovine lungworms in beef herds in 3 western Montana counties (Park, Gallatin, and Ravalli), infected cattle were detected in 27 of 35 herds. Results of 2,125 fecal examinations indicated that 7.8% of all cattle were infected with Dictyocaulus viviparus. Lungworms were found in 6.6% of 1,038 calves (less than 12 months old), 11.5% of 755 yearlings (1 to 2 years old), and 3.3% of 332 cows (more than 2 years old). A distinct seasonal pattern existed in calf infections, with initial passage of larvae beginning in late July or August and persisting until November or December. Exposure of calves in 1 portion of the study area apparently was delayed until November, with patent infections continuing through March. Spontaneous loss of infections normally occurred after 3 to 4 months of patency. The mean rate of larval excretion in the feces of all infected cattle was 0.37 larvae per gram of feces (l/g). Larval output was relatively uniform within each geographic area regardless of host age, but varied considerably from one portion of the study area to another. The potential role of wild ruminants (deer, elk, and moose) in the epizootiology of D viviparus is discussed with respect to western range utilization practices.
在一项于1967年10月至1969年8月开展的针对蒙大拿州西部3个县（帕克、加拉廷和拉瓦利）肉牛群中牛肺线虫分布及季节性流行情况的调查中，在35个牛群中的27个检测到了受感染的牛。2125次粪便检查结果表明，所有牛中有7.8%感染了胎生网尾线虫。在1038头犊牛（小于12月龄）中，6.6%发现有肺线虫；在755头一岁牛（1至2岁）中，11.5%发现有肺线虫；在332头母牛（大于2岁）中，3.3%发现有肺线虫。犊牛感染呈现出明显的季节性模式，幼虫最初在7月下旬或8月开始排出，并持续到11月或12月。研究区域一部分的犊牛接触感染源的时间显然推迟到了11月，显性感染一直持续到3月。感染通常在显性感染3至4个月后自然消失。所有受感染牛粪便中幼虫的平均排泄率为每克粪便0.37条幼虫（l/g）。每个地理区域内，无论宿主年龄，幼虫排出量相对一致，但研究区域不同部分之间差异很大。就西部牧场利用方式而言，讨论了野生反刍动物（鹿、麋鹿和驼鹿）在胎生网尾线虫 epizootiology 中的潜在作用。 （注：epizootiology 这个词可能有误，推测可能是epizootiology，意为兽疫学）
