Eddi C S, Williams J C, Swalley R A
Department of Veterinary Microbiology and Parasitology, School of Veterinary Medicine, Louisiana State University, Baton Rouge 70803.
Vet Parasitol. 1989 Apr;31(1):37-48. doi: 10.1016/0304-4017(89)90006-x.
An epidemiological investigation was conducted during a 1-year period on a permanent pasture naturally contaminated with Dictyocaulus viviparus and grazed by a varying number of yearling cattle. Seasonal variation in pasture infectivity to cattle was monitored by monthly slaughter of tracer calves, slaughter of pairs of resident yearlings at 30-60-day intervals, herbage larval recovery and by counts of first stage larvae in feces (modified Baermann technique) of resident cattle. A clinical outbreak of dictyocauliasis occurred during January-March 1986 and was associated with peak levels of pasture infectivity. Carrier animals were considered responsible for the survival of infection over summer. Although soil samples were taken regularly on a monthly basis to study the epidemiological importance of the soil as a source of infection, infective larvae were not recovered at any time. The epidemiological pattern observed in the present study provides basic information on the factors involved in infection and diseases outbreaks under sub-tropical conditions.
在一年时间里，对一片长期受到胎生网尾线虫自然污染且有数量不等的一岁小牛放牧的牧场进行了流行病学调查。通过每月宰杀示踪小牛、每隔30 - 60天宰杀一对常住一岁小牛、牧草幼虫回收率以及常住牛粪便中第一期幼虫计数（改良贝尔曼技术）来监测牧场对牛的感染力的季节性变化。1986年1月至3月期间发生了网尾线虫病的临床暴发，且与牧场感染力的峰值相关。带菌动物被认为是夏季感染得以存续的原因。尽管每月定期采集土壤样本以研究土壤作为感染源的流行病学重要性，但在任何时候都未发现感染性幼虫。本研究中观察到的流行病学模式为亚热带条件下感染及疾病暴发所涉及的因素提供了基本信息。
