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This article was published in 1974
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Hydatids in Dingoes
A.E. Newsome, Division of Wildlife Research, C.S.I.R.O.
An intensive study of the biology and ecology of the dingo (Canis familiaris dingo) has been underway in the contrasting environments of central and south-eastern Australia since 1966.
No hydatid worms (Echinococcus granulosus) have been found in dingoes from the arid and semi-arid Inland. Heavy infestations exist, however, in dingoes in the mountainous and coastal regions, in the arc from Gippsland, Victoria, to Bateman's Bay, N.S.W. The incidence in dingoes there ranges from 62% (Victorian results) to 84% (CSIRO). This contrasts with a very low incidence of only 1.1% in domestic dogs (Victorian results). Local infestations in domestic dogs in N.S.W. are reported to be as high as 25%, but still far below those in dingoes. No hydatids have been found in feral cats (Felis domesticus) or European foxes (Vulpes vulpes) in Victoria.
A sylvatic cycle is suspected for hydatids in dingoes, the intermediate hosts being kangaroos and wallabies. Hydatid cysts have been found in 27% of swamp Wallabies (Wallabia bicolor) by workers in country inhabited by dingoes in south-eastern Australia, and in 20% in Queensland. Wallabies (W. bicolor and W.rufogrisea) comprise over 40% of the diet of dingoes.
The highest number of worms in any dingo was 89,000 (by dilution) Twelve out of 75 dingoes examined had no worms at all. The average for the rest was 4,600 (by dilution).
Populations of hydatid worms in the gut of dingoes are heaviest about 0.6 to 1m down from the pylorus. An average of 12% and maximum of 40% of worms are adult and can be seen by the naked eye projecting from the villi. Possibly, there is a high degree of host immunity to the worms.
Hydatid control by treating all domestic dogs in Tasmania, where there are no dingoes or feral dogs, indicated that a rapid fall in infection rate can be readily achieved (11% to 3% in 3 years), but that a low incidence (1%) still persisted after the programme had run for 7 years. How much harder will it be, then, to control hydatid infections in domestic dogs on the mainland in regions where a sylvatic cycle exists? It will all depend on the degree of overlap of the domestic and wild cycles. Our current studies of hybridisation of dingoes and domestic dogs in the wild, and the mobility of the two breeds, indicates clearly that such an overlap exists.