Dr Jeff Cave, Senior Veterinary Officer, Buloke Times

You may have recently read that a living roundworm, suspected to have come from the faeces of a carpet python, was pulled from brain of a woman in New South Wales.

It was the first documented case of the parasite infecting a human.

Needless to say, she was extremely unlucky. However, there are other, more common parasites that can infect both animals and humans known as zoonotic parasites.

A zoonotic parasite of significant risk to rural communities in south-eastern Australia are hydatids.

In the past, hydatids were a significant cause of illness in Australian rural communities.

This was largely due to the practice of feeding the offal of sheep to farm dogs, the absence of treatment of tapeworm in farm dogs, and the close physical connection between farmers and their dogs.

Abattoir surveillance data has shown that the risk of hydatids is still present, with one peer reviewed study showing that hydatid cysts were found in 8 per cent of cattle carcasses at a major abattoir in eastern Australia.

To understand how you may become infected with hydatids it is useful to understand the hydatid lifecycle, which has two stages.

The adult hydatid tapeworm lives in the intestine of dogs and dingoes (and foxes to a lesser extent).

The adult tapeworm produces eggs that are passed in the dog or dingo’s droppings.

When sheep, kangaroos and cattle ingest the eggs in contaminated dog or dingo droppings they become infected.

The hydatids then develop into their immature stage as watery cysts in the soft tissues such as the liver and lungs of those animals.

When a dog or dingo ingests raw offal or dead stock that contain the immature cysts, they become infected completing the lifecycle.

Humans can become infected in the same way as a sheep, cow, or kangaroo if they are in close contact with infected dogs.

Children are at particular risk due to their close contact with dogs and their tendency to transfer eggs to their mouths.

When a person becomes infected, cysts may develop in the liver, lungs, or brain.

The consequences of this may be fatal. The only treatment in humans is by radical surgery to remove the cysts.

Hydatid disease can be prevented by following several important steps:

• Worm dogs regularly with an all wormer that is effective against the hydatid tapeworm.
• Never feed raw offal to dogs.
• Promptly dispose of all dead stock.
• Keep dogs kennelled or chained when not working to prevent them finding offal or dead stock.
• Restrict dog’s access to household vegetable gardens and wash all vegetables thoroughly.
• Wash your hands after handling dogs and before eating, smoking etc.

These steps are tried and proven and were used in a coordinated way to successfully eradicate hydatids in both New Zealand and Tasmania.

This article appeared in The Buloke Times, 31 October 2023.