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Protecting your Dog and your Family from Parasites

Getting closer to our dogs – and closer to parasites!

A recent study by Elanco Animal Health reported on the changing relationship between dog owners and their dogs. 

The changes are particularly striking between dogs and new-generation dog owners, particularly those living in urban environments. Many of these owners regard their dog as an integral member of their family, celebrating their dogs' birthdays, buying birthday presents and cooking special meals for them.

Some people also sleep with their dog in their bed. However, while some people’s attitudes to dog ownership may be changing, there is no doubt that closer interaction with dogs has the potential to expedite the transmission of a number of dog-parasites to people. 
There have been two relatively recent studies on parasites infecting dogs. One focused on intestinal worms in rural dogs in eastern Australia[1] found that over 40% of dogs had evidence of hookworm, one in five (21%) had evidence of whipworms, and another 6% had evidence of roundworms

Another study of owned and stray dogs and cats around Australia[2] found that nearly a quarter of all dogs (24%) had gastrointestinal parasites. The findings of both studies reinforce how common parasite infection can be among dogs in Australia and why dog owners need to take steps to protect themselves and their dogs.

What types of Parasites can Infect your Dog?

There are many species of parasites that have the potential to infect your dog – and not all are intestinal worms. A number of other parasites can infect dogs, the most common of which is the water-borne Giardia. However, intestinal worms are also common and they fall into two main groups – roundworms and tapeworms. 

The most common types of roundworms and tapeworms are: 

Common name
Scientific name
Common name
Scientific name
*Common dog roundworm
Toxocara canis
Flea tapeworm or cucumber seed tapeworm
Dipylidium caninum
Trichuris vulpis
Zipper tapeworm
Spirometra erinacei
*Ancylostoma species and Uncinaria stenocephala
Sheep measles tapeworm
Taenia ovis

Bladder worm tapeworm
Taenia hydatigena

Taenis pisiformis

Taenia serialis

Hydatid tapeworm
Echinococcus granulosus
((*Zoonotic = infects humans) 

How parasites make the ‘jump’ from pets to humans

A number of these parasites don’t just infect dogs, but they can also infect humans as well. The common dog round worm is the type of round worm that can have the most adverse human health impacts.

Intermediate host
*Flea tapeworm or cucumber seed tapeworm
*Zipper tapeworm
Water fleas (copepods) and frogs
Sheep measles tapeworm
Bladder worm tapeworm
Taenis pisiformis
Taenia serialis
*Hydatid tapeworm
Sheep, cattle, kangaroos, wallabies, wombats, feral pigs

(*Zoonotic = infects humans)

Accidental ingestion of common dog roundworm eggs (most commonly by children under five years old) can result in blindness. 

After someone accidently ingests the eggs, for example by putting their fingers in their mouths after coming into contact with their dog or eating soil (pica), the ingested egg hatches in the intestine, a larva is then released which passes through the intestinal wall and migrates around in the body. 
Most larvae are eventually killed by our immune system but occasionally a larva finds its way to the back of the eye and breaks into the human eye through the retina. While rare, there are a number of cases in Australia every year.

Hookworms can also be transferred from our pets to humans. Following the release of hookworm eggs into the environment in dog faeces (dog poo), after a day or so a larva develops in each egg. 

The larvae break out of the eggs and continues its development in the environment (so in grass for example) to the infective stage. The infective larvae are then able to penetrate the skin, which in dogs is usually the skin between the pads of their feet. In humans the larvae penetrate the skin of the instep and between the toes, leading to itchy and painful areas on the feet that if scratched with dirty fingers may become infected. 

Occasionally, larvae migrate into the human intestine and cause eosinophilic enteritis – a disease that can lead to nausea, vomiting, abdominal pain, and occasionally diarrhoea. 
The ability for hookworms to be transferred from our dog’s poo to a human is just one reason why picking up after your dog is so important!

The flea tapeworm also occasionally infects humans. Like the common dog roundworm, this is mostly in very young children living in homes with dogs infected with tapeworms and fleas. The flea larvae feed on shed skin flakes, and also tapeworm eggs, in the bed of the dog or cat. The tapeworm eggs hatch inside the flea larvae and the immature tapeworms stay in the larva as it develops into an adult flea. 

If an infected flea is accidentally eaten by a dog or human a tapeworm develops in the intestine.
The other tapeworm that humans need to be weary of is the hydatid tapeworm. This parasite can be quite dangerous to those infected, including death in severe cases. 

The hydatid cysts occur in livestock and wildlife livers and lungs (offal) but the dangerous hydatid tapeworms are transferred to dogs when they eat raw or uncooked offal or access an animal carcass. 

Dogs may become infected with other tapeworms through eating raw sheep meat or infected with roundworms through contact with the poo of another dog. Once dogs are infected with hydatid tapeworms, they develop in the intestine of dogs. Eggs released by the tapeworms can then be transferred from our dogs to humans causing hydatid disease (cysts in liver and lungs). 

This parasite is less common in humans than 20-30 years ago but is still a risk with cases occurring every year in Australia.

How to reduce the chances of your dog and your family getting infected by parasites:

#1. Practice good hygiene

Always wash your hands after playing with your dog and do not to let it lick your face. This helps minimise the risk of passing on any flea or hydatid tapeworm segments or eggs.

#2. Dispose of your dog’s droppings

It’s easy to forget but making this a habit is a great way to remove tapeworm segments or eggs from your environment, which lessens the risk of your family becoming infected. This includes picking up after your dog in public and keeping dog pens, your garden and areas around kennels free of dog poo.

#3. Regularly de-worm your dog

You want a product that contains the active ingredient praziquantel, which kills adult flea and hydatid tapeworm and any other tapeworm that may be living in your dog’s intestinal tract. 
Rural dogs with the opportunity to hunt, roam and scavenge carcasses are far more at risk of tapeworm infection and need more frequent de-worming than an urban dog fed commercial dog food and walked in an urban park.

#4. Prevent your dog accessing dead animals or poo from other dogs.

#5. Ensure your dog has a healthy diet and if you wish to feed your dog meat or offal you should freeze the meat or offal for 10 days or cook it well before feeding it to your dog.

Written by David J JenkinsAssociate Professor in Veterinary Parasitology, School of Animal and Veterinary Sciences, Charles Sturt University (Wagga Wagga, NSW) for Australian Dog Lover (all rights reserved)

[1] Jenkins DJ, Lievaart JJ, Boufana B, Lett WS, Bradshaw, Armua-Fernandez MT (2014) Echinococcus granulosus and other helminths: current status of prevalence and management in rural dogs of eastern Australia. Australian Veterinary Journal 92; 292-298.

[2] Palmer CS, Thompson RCA, Traub RJ, Rees R, Robertson ID (2008) National study of the gastrointestinal parasites of dogs and cats in Australia. Veterinary Parasitology 151; 181-190

About the Writer

David Jenkins – Associate Professor in Veterinary Parasitology and Senior Research Fellow, School of Animal & Veterinary Sciences, Charles Sturt University, Wagga Wagga, NSW.
David was born in the UK and attended the University of London where he completed a BSc in botany and zoology. This was followed by an MSc in immunology also in London. He then spent two years in Indonesia working on hookworms in humans. From Indonesia he went to the vet school at the University of Melbourne where he gained a PhD studying the immune response of dogs to infection with tapeworms.

After his PhD studies David sent 2 years in north-western Kenya as a researcher on a hydatid control program and then returned to Australia as a research officer on a hydatid control program based in Canberra. During the following 18 years in Canberra David undertook studies investigating the role of wildlife in the transmission of hydatid disease in south-eastern Australia. He also undertook commercial research projects for the Australian veterinary pharmaceutical industry testing new de-wormers for dogs and cats against hydatid tapeworms.

During this time David also taught veterinary parasitology at the University of Sydney, medical parasitology at the Australian National University (ANU) and the University of St George, Grenada and general parasitology to science students at the ANU. He joined the School of Animal and Veterinary Sciences at Charles Sturt University in 2008. He teaches veterinary parasitology, supervises post graduate students and undertakes his own research.

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