Host specificity of abomasal nematodes in free ranging alpine ruminants.
Abomasa from 641 alpine wild ruminants representing five different species (76 Cervus elaphus, 280 Capreolus capreolus, 101 Rupicapra rupicapra, 155 Capra ibex, 29 Ovis musimon) and from 19 domestic sheep (Ovis aries) from alpine areas of Italy were examined in order to investigate host-specificity. Nine of the 20 helminth species found were present in at least five different host species. A discriminant analysis was able to significantly discriminate the hosts on the basis of their helminth community composition with the exception of O. musimon and O. aries. Based on the correlation between each variable represented by helminth species with the most explanatory discriminant axis, it was possible to classify helminths into specialists and generalists. Specialists are represented by the dominant species in a community of a host species or family whereas generalists appear in the communities of many different hosts as intermediate species. Due to the pathogenic potential of some of these generalist species (i.e. Haemonchus contortus, Trichostrongylus axei) and their ability to adapt easily to the conditions found in several different hosts, they appear to be the most important from a sanitary point of view. The dominant helminths in cervids were Spiculopteragia spiculoptera and Ostertagia leptospicularis, and in bovids were Teladorsagia circumcincta and Marshallagia marshalli.