Morphological characterisation of Australian strains of Echinococcus granulosus

Kumaratilake L. M. and Thompson R. C. A., 1984. Morphological characterisation of Australian strains of Echinococcus granulosus. International Journal for Parasitology14: 467–477. Previous studies utilising biochemical and developmental criteria demonstrated the occurrence of three distinct strains of E. granulosus in Australia. In order to further characterise these strains, we studied metacestode and adult morphology of E. granulosus of various domestic and wild animal origin from different geographical areas of Australia. Morphological comparisons included specimens from natural infections as well as experimentally-derived adult worms of known age. Three morphologically distinct populations of E. granulosus were recognised in domestic and wild animals. These populations corresponded to the three strains described previously on the basis of biochemical and developmental criteria. One strain is common to all domestic intermediate hosts on the Australian mainland, the second is confined to macropods on the mainland and the third to sheep in Tasmania. No evidence was found that domestic animals on the mainland are susceptible to the sylvatic macropod strain, whereas 15% of macropods examined were infected with the mainland domestic strain. Natural infections with both mainland strains were found in dogs and dingoes. The practical value of morphology as a criterion in taxonomic and speciation studies is discussed. Suggestions as to the probable origin of the three Australian strains of E. granulosus are given.