Research Article

Rostellar hook morphology of Echinococcus granulosus (Batsch, 1786) from natural and experimental Australian hosts, and its implications for strain recognition

R. P. Hobbsa1, A. J. Lymberya1 p1 and R. C. A. Thompsona1

a1 Institute for Molecular Genetics and Animal Disease, and School of Veterinary Studies, Murdoch University, Murdoch, Western Australia, 6150, Australia

An analysis of the rostellar hooks of Australian isolates of Echinococcus granulosus revealed that there was less variation in larval (metacestode) than adult characters and that metacestode characters could be measured directly from adult worms. A factor analysis indicated that two factors, one representing a contrast between number of hooks and their length, and the other representing blade lengths, were sufficient to account for 87.5% of the variance in metacestode hook measurements. These results indicate that rostellar hook morphology is not useful for discriminating strains of E. granulosus in Australia. The Tasmanian and mainland domestic strains were found to be indistinguishable using rostellar morphology. Although many of the isolates from sylvatic hosts differed from those from domestic hosts, there was not a clear separation as would be expected if two distinct strains existed. Evidence was presented to show that the morphological differences seen in sylvatic hosts could be attributed to host-induced effects, and that the previously accepted existence of two mainland strains should be investigated further.

(Accepted March 25 1990)


p1 Department of Agriculture, Baron-Hay Court, South Perth, Western Australia 6151, Australia.