Dr Jacobson, who is completeing a research fellowship at Murdoch University, believes while sheep measles, or Taenia ovis, is not a human health hazard, it is most definitely a wealth hazard.
“Presence of the parasite is not acceptable in the human food chain and carcass condemnation, or complete bone-out, regularly occurs in abattoirs due to the presence of cysts.
“As the cysts cannot be detected in live sheep and is only diagnosed at slaughter, abattoirs bear the cost burden. However, some have moved to keep a register of properties from where infected sheep are coming.
“Infection need not occur as there are proven means of breaking the parasite life-cycle,” Dr Jacobson said.
Sheep measles represent the intermediate or larval cyst stage of the tapeworm Taenia ovis.
It occurs in Australia wherever there are sheep or goats and dogs. And like the sheep hydatid tapeworm, the key to control is breaking the cycle: dog –> dog faeces –> pasture –> sheep –> sheep meat (or offal) -> dog.
The key steps are:
• preventing dogs from eating sheep or goat meat or their offal
• treating dogs regularly with an efficient tape-wormer (praziquantel)
• cooking or freezing sheep meat/offal fed to dogs helps reduce the spread from sheep to dog
As domestic dogs pass lots more T. ovis eggs than foxes and dingoes, the emphasis should be on treating farm dogs regularly as research shows that these are by far the most important source of infection.
Sheep carry cysts for a long time so farms with an ovis problem may have infection problems for years to come, even with regular treatment of dogs. Prevention is the only approach to stop economic losses for producers and processors.
DAFWA District Veterinary Officer, Narrogin, Dr Anna Erickson, says preliminary DAFWA research on the incidence of sheep measles using abattoir data shows up to 80per cent of lines have been exposed at some stage, 3pc of lamb carcasses were affected and 3.5-6pc mutton carcasses affected.
“This is quite a high incidence. It seems the message about controlling T. ovis might have been forgotten.
“DAFWA’s survey work is aiming to establish where the control measures for T. ovis are breaking down.”