A VACCINE for the prevention of sheep measles (Cysticercus ovis) may be on the cards for producers in a matter of years if industry collaboration can find the funds to get it off the ground.
Sheep Alliance of WA chairman Dr Heggaton said recognition of the need for a vaccine against sheep measles – which is costing the sheep meat industry at least $2.5 million a year – had led to “initial talks” though “more accurate research was needed”.
He said there was a need for a funding grant for a scoping study, which once concluded, a drug company would be willing to invest in developing the vaccine – where it would recover its costs.
Dr Heggaton said it was likely that the vaccine would be incorporated into an existing vaccine to make it user friendly and not be a stand-alone additional jab that producers had to purchase for their flocks.
Sheep measles is a major concern across WA – impacting on profitability and meat quality.
Charles Sturt University, parasitologist Dr David Jenkins, from the School of Animal and Veterinary Sciences, Wagga Wagga, New South Wales, said most of the commercial losses from sheep measles were borne by the processors, so the vaccine would need to be marketed so that farmers would want to use it.
“There needs to be co-operation between all sectors of the industry and research funding to get this vaccine to a stage where it can be registered for use in Australia,” Dr Jenkins said.
He said that “mutton processors in WA appear to be the worst affected, losing an average of $2138 per day, however, daily spikes may be in excess of $4000 per day” (2014 figures).
It was recorded in a Sheep Measles Fact Sheet in 2015 that in 2013-2014 between 40 to 90 per cent of properties had evidence of sheep measles infection in lines monitored at abattoirs across Australia.
Dr Heggaton said processors had been impacted quite severely by sheep measles – with a certain area of the State having up to 5pc of carcases affected.
“It is more widespread than what people realise,” he said.
“And it’s getting worse.
“People are not paying much attention to it.”
According to the Department of Primary Industries and Regional Development (DPIRD) veterinary officer Dr Anna Erickson, based in Narrogin, about 70pc of lines in WA were affected to some degree by the parasite.
She said when sheep carcases were x-rayed at the processors they would pick up whether it had been impacted or not.
If five or more nodules, or hard cysts, were found in the meat then the carcase would be condemned because it was unsellable – particularly to export-sensitive markets like the United States and Japan.
Dr Erickson said in her research conducted in the early 2000s “WA had more sheep than any other State infected” by sheep measles – about “60pc of farms”.
While she admitted there was still “a lot we don’t know about sheep measles” what is known is that once sheep were infected and a cyst formed “it stays there forever”.
“There’s nothing you can use to get rid of it,” Dr Erickson said.
However, she said the “principles of control are very easy”.
“It’s a big issue and it’s hard to control having farm dogs that come into contact with sheep.
“Farm dogs need to be wormed every month.”
Dr Erickson said while farmers may worm their dogs regularly, the problem extended to visiting dogs that came onto the farm with contractors and neighbours, as well as foxes.
“Other people’s dogs coming onto the farm can bring diseases onto the property,” she said.
“Contractors dogs are a big risk, unless they know that they have been wormed it’s quite a big risk.”
Sheep measles originate when the sheep eat the tapeworm, Taenia ovis, eggs on pastures after being dropped from dogs or foxes through their faeces.
Once ingested the eggs hatch and the larvae migrate through the body, settling in the muscles, heart and diaphragm.
The cysts are initially filled with fluid but these degenerate over time to become hard calcified scars – which although are not harmful to human consumption, or to sheep health, they impact the trimming, downgrading and condemnation of sheep meat at abattoirs.
Dogs become infected with tapeworms by eating sheep meat or scavenging carcasses with viable cysts.
Once ingested by a dog the tapeworm is capable of producing viable eggs within 35 days.
Each tapeworm in a dog can contaminate pastures with 180,000 to 360,000 eggs per day.
The eggs can be spread by flies, the wind and rain, and a single infected dog can infect sheep in a wide radius of up to six kilometres.
In 2014 Dr Jenkins released research conducted over a two-year period revealing that foxes were also recognised as a possible host for the sheep measles parasite.
The finding suggested that the practice of worming domestic dogs was vital but was not enough to protect sheep from the parasite.
Dr Jenkins has since called for the commercialisation of a vaccine to prevent sheep measles.
During the study molecular techniques for identifying infection were used to examine fox carcases collected through vertebrate pest control programs and recreational shooters in New South Wales and WA.
“We’re roughly looking at about one per cent of foxes infected with this parasite in certain areas,” Dr Jenkins said.
“Although it doesn’t sound like very many, if you consider that the eggs remain infective for at least 300 days, the odds are stacked in favour of the parasite being transmitted.
“This is important because foxes are everywhere.
“Gross examination of intestinal contents post-mortem revealed sheep wool was commonly present in fox intestines in WA (22.3pc),” the report said.
“Therefore our gross observations are likely to be an under estimation as to the level of predation/scavenging of sheep by foxes in WA.”
Dr Erickson said it was another good reason for farmers to shoot and trap foxes and wild dogs – to ensure that despite the research done their sheep were not as exposed to sheep measles.
While all WA processors are dealing with the issue, Western Australian Meat Marketing Co-operative (WAMMCO) was able to provide some insight into the impact sheep measles had on the business.
WAMMCO quality assurance manager Marc Chambers said sheep measles impacted processors in a variety of different ways – always impacting on efficiency and profitability.
“It impacts the meat processing industry financially, in quite a few ways,” Mr Chambers said.
“Firstly, there is an immediate rejection of carcases affected by more than five Cysticercus Ovis.
“Carcases with less than five cysts need to be totally boned out and re-inspected, causing yield and profit loss.”
Mr Chambers said there was also a United States Port of Entry rejection possibility for pathological defects, both prior to export and at entry to the US.
He said failure of internal Meat Hygiene Assessment parameters meant that there was a “potential defrost of production lot, and rework”.
Processors also had to deal with customer complaints for affected product if not detected.
