The prevalence and epidemiology of Anoplocephala perfoliata infection in Norway.

The caecum and the adjacent 30 cm lengths of ileum and large colon of 201 horses from two different regions of Norway (Ostlandet and Trøndelag) were examined for the presence of Anoplocephala perfoliata. In all, 20% of the horses were infested with the cestode (27% in Ostlandet and 7% in Trøndelag). The mean number of worms in infected horses from the two regions was 18 and 6, respectively. Information was obtained on the age, sex, breed, type of pasture and anthelmintic treatment after the grazing season for 183 of the 20 horses. The degree of infestation with A. perfoliata was not influenced by age, breed or sex. The odds ratio (confidence limits) for using permanent pastures that had been grazed by horses for at least the 5 last years in succession was 8.8 (3.2-24.4). There was a significantly higher prevalence of A. perfoliata infestation in Ostlandet (odds ration 3.1 (1.1-9.1). The relatively low prevalence of A. perfoliata infestation in Norwegian horses compared to the reported prevalences in other countries and the differences in the prevalence between Ostlandet and Trøndelag are discussed. Gross pathological examination identified lesions such as mucosal thickening, hyperaemia and/or erosions. These lesions were found in all of the infected horses, compared with only 5% of the non-infected horses. Examination of faecal samples from 26 of the infected horses detected cestode eggs in only three cases. It was concluded that faecal examination is an inadequate method for the diagnosis of A. perfoliata infestation.