Urquhart G M, Jarrett W F, Bairden K, Bonazzi E F
Vet Rec. 1981 Feb 28;108(9):180-2. doi: 10.1136/vr.108.9.180.
A 16-day infection of Dictyocaulus viviparus in two groups of calves was treated with levamisole and fenbendazole respectively. Five days afterwards the calves were reinfected with 4000 larvae and necropsied 21 days later. Although the lungworm burdens of the two groups of calves were reduced by about 70 per cent compared to a control group the clinical signs of dyspnoea, tachypnoea and coughing were indistinguishable from a primary infection. This was due to pulmonary emphysema, oedema and an acute epithelialising pneumonia apparently associated with the death and disintegration of lungworms in situ, the result of an incompletely developed immune response. The results are compared with those obtained with the lungworm vaccine. It was concluded that the outcome of any system of "control" which depends on drug therapy and reinfection is unpredictable and that vaccination offers the only effective method of prophylaxis.
分别用左旋咪唑和芬苯达唑对两组犊牛进行为期16天的胎生网尾线虫感染治疗。五天后，犊牛再次感染4000条幼虫，并在21天后进行剖检。与对照组相比，两组犊牛的肺线虫负荷虽降低了约70%，但呼吸困难、呼吸急促和咳嗽等临床症状与初次感染并无差异。这是由于肺气肿、水肿以及明显与原位肺线虫死亡和崩解相关的急性上皮化肺炎所致，这是免疫反应发育不完全的结果。将这些结果与使用肺线虫疫苗所获得的结果进行了比较。得出的结论是，任何依赖药物治疗和再感染的“控制”系统的结果都是不可预测的，而疫苗接种是唯一有效的预防方法。
