The infection caused by a small tapeworm was once common in Tasmanian dogs and sheep, and killed several adults and children before the state government backed a control program in the 1960s.

In 1996, Tasmania was declared provisionally free of hydatid disease.

But Charles Sturt University senior research fellow David Jenkins said he was surprised by the number of hydatid infections he detected in Tasmania during a study on the prevalence of the infection in eastern Australia.

The study, published in the Australian Veterinary Journal earlier this month, found that of 306 samples from Tasmania, 24 (7.8%) tested positive to the hydatid infection.

‘‘The important thing to say is we never saw tapeworms in the dogs, all our results are based on substances released by the tapeworms,’’ Dr Jenkins said.

‘‘We backed that up by looking for hydatid tapeworm DNA in the dog faeces, and we certainly found it in three or four of them.’’

Dr Jenkins said that while he did detect more cases than expected, the parasite remained at low levels and there was no need for alarm.

‘‘The implications are that the parasite’s there and my feeling is that we need to try and determine what’s actually going on,’’ Dr Jenkins said.

But Dr Andrewartha said the study results were not a reflection of infection rates across Tasmania’s dog population.

He said the Department of Primary Industries provided Dr Jenkins with the study samples, from dogs on or near properties where hydatid infections had already been detected in cattle.

Dr Andrewartha said hydatid cases were not increasing, and he was comfortable with the 122 infection notifications received since provisional freedom was declared in 1996.

‘‘Since the start of last calendar year there’s only been one sheep and one cattle cyst detected that we’ve been advised of,’’ Dr Andrewartha said.