Cattle

[Extract] A considerable number of nematode species occur in the gastrointestinal tract (GIT) of cattle and their occurrence does vary to some extent according to geographical area. In temperate areas only three are regularly of major importance. These are the strongylid nematodes Ostertagia ostertagi, Trichostrongylus axei and Cooperia oncophora. In warmer areas of northern Australia Oesophagostomum radiatum and Haemonchus placei are more common as are Cooperia punctata and Cooperia pectinata. There are also several minor strongylid species that occur in smaller numbers in mixed infections, namely: other species of Ostertagia (for example O. leptospicularis), small intestinal Trichostrongylus spp., Bunostomum phlebotomum and Nematodirus helvetianus. In addition to these strongylid species, cattle can be infected with small burdens of Trichuris spp. and the cestodes Moniezia expansa and M. benedeni which are both of limited clinical significance. As well as these recognised cattle parasites, young cattle especially can be temporarily infected with some nematodes more usually considered to be sheep nematodes (e.g. H. contortus and T. colubriformis). Although this is not clinically significant, it can be a means of transferring isolates of some species that have anthelmintic resistance