Hydatids Now History, But Care Needed To Keep It Away

18 September 2002

New Zealand has been declared provisionally free of hydatids and notification of this freedom is today being announced to the OIE - the international animal health organisation.

The Ministry of Agriculture and Forestry's Director of Animal Biosecurity, Derek Belton, says a significant milestone has been reached with this declaration, which has been made after a decade of virtually clear surveillance results.

Hydatids is caused by a tapeworm which lives in the gut of dogs. Its life-cycle also involves an intermediate host, which in this country is mainly sheep or sometimes cattle. Humans can also be a host and hydatids can pose a serious risk to human health through the formation of cysts in vital organs.

Since 1946, the highest number of people per year in New Zealand who were hospitalised with hydatids was 103 in 1953. This compares with seven cases notified to the Ministry of Health in 2001. These people were aged between 44 and 72 and would have caught the infection as children, with the disease causing problems many years later. New infections have been rare since the 1970s.

Dr Belton says MAF has opted for declaring 'provisional' freedom only at this stage. "Given the long life cycle of the disease, it would be premature to say we're totally in the clear. If, after five years of animal screening, we find no further evidence of hydatids, we will be able to make a case for what's known as 'full country freedom'," he says.

Achieving this provisional free status is quite a coup for New Zealand. Hydatids is widespread in the world and eradication has only been attempted on geographically remote islands including Iceland, the Falklands, Cyprus and Tasmania.

Derek Belton says the successful eradication is due largely to the enormous effort made by field officers and local authority hydatids control officers who, under the direction of the National Hydatids Council, worked for 45 years to rid New Zealand of the parasite.

"Many Kiwis will remember the visits by hydatids control officers to dose the pet dog, or the dog dosing strips around the country."

Dr Belton stresses that continued controls and vigilance are now needed to stop the disease returning. Inspectors will continue checks for hydatid cysts in animals at abbatoirs and export meat works. And farmers need to follow strict guidelines on home-killing stock and the feeding of dogs on the farm. These are:

* Ruminants and pigs in home-killing facilities must be slaughtered within a dog-proof enclosure * Owners must ensure dogs are controlled so they're not able to access offal (liver and lungs of ruminants and pigs) in carcasses that may be lying undetected on properties * Offal must be boiled for 30 minutes before feeding to dogs

"Imported live animals are a potential risk pathway for re-introducing the parasite because it's so widespread globally," Derek Belton says. "All imported sheep, goats, deer and cattle must be identified and their whereabouts or fate reported to MAF annually. Any deaths of these imported animals outside the controlled environment of a slaughterhouse will trigger an exotic disease response and active surveillance on the property where the animal died."


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