Sheep measles bill under microscope

Kate PollardCountryman

WA's sheep belt has the highest prevalence of sheep measles in Australia.

A leading parasite researcher believes the disease could be spread by foxes.

Charles Sturt University senior research fellow David Jenkins is investigating the financial impact of the parasitic infection, which is spread by dogs, on the Australian sheepmeat industry and if it can be transmitted by wildlife.

Abattoir inspectors from the National Sheep Health Animal Monitoring Program, co-ordinated by Animal Health Australia, found the prevalence of sheep measles was widespread in WA, medium in New South Wales and Victoria and low in Tasmania.

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But before producers begin to panic, Dr Jenkins said there was no impact on animal or human health.

"It's all to do with aesthetics but it could impact on producer returns and overseas trade," he said.

In the 1960s, 82,000 cartons of boned-out sheep mutton was rejected by the US and returned and processed into dog food in Australia because sheep measles was detected in the meat.

Meat and Livestock Australia recently provided $429,000 of funding over two years to research sheep measles, also known as Taenia ovis (T.ovis).

It starts when sheep are infected by grazing pasture contaminated with T.ovis eggs that have been shed in dog faeces.

Dogs are infected with the adult tapeworm stage of the parasite, which can grow up to 2m and are found in the intestines.

During its larval stage sheep measles is found in the muscles of sheep as cysts, which cause carcases to be downgraded.

When these cysts, which each contain a tapeworm head, are eaten by a dog, the adult parasite develops in the dog's intestine and the lifecycle continues.

"Predominantly the parasites go to the heart and diaphragm of sheep, which is where meat inspectors look first," Dr Jenkins said.

"If there is a cyst in the diaphragm and/or heart, they start to look at the rest of the body and if there are five or more cysts discovered, the whole carcase is thrown away."

With help from four abattoirs, including Fletcher International in Narrikup, Dr Jenkins will determine the cost to industry, including condemned carcases and the time and cost of trimming.

Data will be collected from 20,000 sheep four times a year to check for seasonal change and see the impact on different aged livestock.

In the past, the cost has been borne by processors and reportedly cost WAMMCO $250,000 five years ago.

Farmers are also bearing the brunt of the disease.

A South Australian farmer recently lost $3000 after 90 per cent of his 305-sheep consignment was infected with sheep measles and 27 carcases had to be thrown away.

To help with the project, Dr Jenkins is calling on farmers to complete and return a questionnaire looking at on-farm risk factors.

He also wants farmers with sheep measles to contact him.

"I also really need farmers without an identified sheep measles problem to contact me because we need to have these people as a comparison to those with a problem," Dr Jenkins said.

The life cycle of T.ovis is also being revisited and Dr Jenkins is investigating if it can be transmitted by foxes and wild dogs, such as dingoes and dingo/domestic dog hybrids.

A small study involving 45 foxes found 16 had tapeworms and one had a T.ovis tapeworm.

"This is an important finding as based on previous findings, foxes were not thought to act as a host for T. ovis," Dr Jenkins said.

"What we haven't determined is if those eggs are infective to a sheep and chances are they will be."

If wildlife is involved in transmitting sheep measles, Dr Jenkins said deworming dogs and not feeding raw sheepmeat to dogs would need to be backed up by vaccination of sheep.

A vaccine, almost 100 per cent effective, has already been developed and was previously registered for use in New Zealand but due to a marketing miscalculation, was never used.

Dr Jenkins said the next step was to incorporate it with other vaccines commonly used at lamb marking and register it in Australia.

In the interim, Dr Jenkins said farmers needed to continue worming their dogs and make sure they did not let them eat raw sheep meat unless it had been frozen for 10 days.

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