The hydatid tapeworm has its most dangerous impact on humans. The Crookwell district has, at times, been infamous for the frighteningly high incidence of potentially fatal human hydatidosis. Maintaining strict worming regimes is as important for your health as it is for the health of your working dogs or pets.
The hydatid tapeworm is tiny – only 4 to 6mm – and very difficult to see in the droppings. While the true hosts are dogs, dingoes and foxes, the tapeworm requires other animals – intermediate hosts – to complete its life cycle. These are many and varied and the parasite is now widespread in domestic livestock and wildlife, including sheep, goats, cattle, pigs, horses, kangaroos and wallabies.
Humans can also act as an intermediate host.
It’s important to understand people don’t become infected by eating offal or meat – they develop hydatid cysts like all other intermediate hosts by inadvertently picking up tapeworm eggs from dogs. These eggs have passed out in the faeces of infected dogs, and are easily picked up from the dog’s coat or rugs, for example. Grazing animals pick up the tapeworm eggs when grazing pastures contaminated with dog droppings.
Once the eggs are swallowed, they can develop into hydatid cysts in the intermediate host’s internal organs, especially the liver, heart and lung. The life cycle is completed when a dog, dingo or fox eats material containing hydatid cysts (for example, sheep liver) and becomes infected with hydatid tapeworms – see the life cycle diagram below.
Diagram courtesy Department of Primary Industries, Parks, Water and Environment, Tasmanian Government
Prevention and control
Most adult dogs should be wormed every 3 months for life. Farm or pet dogs fed offal, or with access to offal via dead livestock or wildlife such as kangaroos, must be wormed every 6 weeks, alternating between an allwormer (that covers roundworms, hookworms, whipworms) and a tapewormer for life.
To be effective against the hydatid tapeworm, the tapeworm product must be a praziquantel-based product such as Droncit.
Access to offal
Make sure your dog does not have access to offal, either on your farm or your neighbours’ properties, or by feeding offal as part of the diet. The safest and best balanced diet for dogs is good quality manufactured dog food.
Wash your hands thoroughly after handling your dogs, their rugs, feed bowls and grooming gear. Teach your children too about the importance of hand washing after playing with their pet – it may save a life.