ARCHIVE FILE
This article was published in 1978
See the original document
Hydatid Disease
T.C. Beard, 0.B.E., M.A., MB., B.Chir., M.P.H., Senior Medical Officer, Community Health Branch, Commonwealth Department of Health, Woden, A.C.T.
My aim is to give you a thumbnail sketch of the campaigns against hydatid disease in Iceland, New Zealand, Tasmania and Cyprus, and to end with a short reference to the position in New South Wales.
In Iceland the program was aimed exclusively at Echinococcus. The technology of an annual arecoline purge probably had little if any direct influence on the outcome. By the time modern technology was available there was no need for it and no attempt has been made to introduce it. The parasite has disappeared from the dogs, the sheep and the human population, apart from a few old calcified lesions still being found occasionally in old people.
This result has been attributed to intensive education, over a long period, in a highly literate, law-abiding, small island community. There were also a large number of accidental factors peculiar to Iceland, of which only a few can be mentioned here. The precipitate fall in human incidence over the first 30 years was probably helped by three very severe outbreaks of canine distemper, each of which left many households without a single surviving dog. For climatic reasons the educational message was very simple in Iceland. As grass grows only for 5 summer months, sheep are slaughtered only in the autumn (September - October), so to farmer only had to be persuaded to feed his dogs normally, and deny them offal during the short period that it was available. A change in consumer attitudes led to the slaughter of lambs at 5 months (too young for fertile cysts). With increasing demand for milk, cows displaced milking ewes from the contaminated pasture near the homestead and old cows were usually sent to the abattoir. A meat subsidy designed to keep primary industry viable had the incidental effect of abolishing home slaughter for all but a few uneconomic animals. The authorities nevertheless must be given credit for the educational result and for 100% meat inspection, which is achieved by recruiting medical students among others during the slaughtering season.
In New Zealand a large number of voluntary schemes preceded the national program. Even then the details of control were up to each local authority, but every local plan had to meet national approval, so in practice they all follow similar principles. The original Hydatid Act of 1959 defined both E. granulosus and T. hydatigena as hydatids and the 1968 Act included T. ovis.
The basic philosophy is prevention, with arecoline surveillance. Since the advent of bunamidine in 1965, taeniacides have been given to positive dogs (test-and-treatment) and since 1968 penalties (re-dosing charges) have bean applied. Mass treatment with bunamidine was given extended field trials and with the availability of niclosamide it became the standard technology against T. hydatigena and T. ovis. Owners were expected to continue withholding offal and untreated sheep meat, and a random arecoline test was given 1-3 times a year instead of the 6-weekly niclosamide, to detect offenders. Praziquantel is now widely replacing niclosamide.
Delegating responsibility to about 90 local authorities introduces the risk of a patchy performance in some areas, but it effectively breaks up the substantial hydatid control budget, so that Parliament is not asked to approve it in a lump sum.
Tasmania planned a control program in 1960, and in late 1963 the State Government decided to implement it. During the interval there was a voluntary committee activity, modelled on the voluntary stage in New Zealand. Control is aimed only at at E. granulosus. The educational message to owners was:
DOGS
1. Keep them under control
2. Feed them properly (no offal)
SHEEP
3. Kill in dog-proof area with dog-proof drainage
4. Destroy offal
5. Destroy carcases.
The Department of Agriculture set out to:—
1. Identify problem owners by arecoline surveillance and abattoir inspection
2. Obtain co-operation by education
3. Apply legal pressure where (2) failed.
Tasmania was able to use the provisions of the Stock Act, without special legislation, by defining dogs as stock and hydatid infestation as a disease. Strong public support permitted compulsory testing, followed later by quarantine of infected properties. This was applied at first for ownership of a positive dog, and later also for heavily infected lines of sheep at the abattoir. Results are mentioned briefly below.
Cyprus again aims only to control E. granulosus. Sheep husbandry is done on an extremely small scale, with flocks of 50 animals or less in one ownership. The owner tends them all day, like an old Testament shepherd. Having no freezer, he sells sheep to the village butcher and buys meat as he needs it. The butcher used to be the villain. Cystic offal he could not sell was thrown to the village dogs. Now he slaughters under supervision in a new village abattoir. A vigorously enforced campaign has eliminated all stray dogs and arecoline surveillance is carried out every 4 months, with infected dogs being shot.
In New South Wales, an educational programme was started in 1970 by the Health Commission which was very successful in arousing public awareness. Largely on the advice of local medical and veterinary practitioners, owners were encouraged to treat their dogs with vermifuges. This of course means that arecoline surveillance will never be effective to the point where it could be used to impose quarantine. Arecoline surveillance, which in other areas has enabled E. granulosus to be practically eliminated at relatively low cost, is now of historic interest on the Australian mainland. There are perhaps two mitigating features. Firstly arecoline is relatively unreliable against T. ovis, and I understand that this parasite would almost certainly be included in any further control programme in this country. Secondly, arecoline surveillance requires a restricted market for taeniafuges and taeniacides, and this has become quite impractical in view of the flood of highly effective drugs of low toxicity now being offered by a number of manufacturers. In the opinion of many, the future technology of control lies with mass medication.
I must end with a remark on the human incidence of hydatid disease. Both New Zealand and Tasmania have obtained a big decline in new hospital admissions for hydatid disease and a particularly interesting feature is that this has occurred in all age groups. It is clear from this that adults are relatively susceptible (contrary to former belief) and that a program elsewhere can be expected to bring early benefit to the whole community, including even the elderly.