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.
Statistics from Altmetric.com
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.