Zoonotic parasites

Which parasites affect humans as well as dogs?

This is from my ISCP Diploma in Canine Psychology course:

Ectoparasites are parasites that live on the skin of animals, endoparasites are those that live inside the organs of animals. Common ectoparasites that affect dogs are fleas, ticks, mites and lice. Common endoparasites that affect dogs are heartworm, hookworm, tapeworm, roundworm, whipworm.

Humans can be susceptible to the bites of ectoparasites that attack dogs. Fleas can leap off dogs onto their owners, and bite their way up from ankles to the torso. Their bites are very itchy! Lice can also find their way from dogs to humans. Mites cause mange in dogs, there are three main types – Demodectic mange, Cheyletiella mange and Sarcoptic mange. Mange is generally seen as itchy, scaly, flaky, bald patches on the skin of the animal. Mange mites can also transmit to humans.

In Australia, the tick to watch out for is the Paralysis Tick, or Ixodes holocyclus, a native tick endemic on the East Coast of Australia, especially on the Gold Coast, that causes paralysis first of the lower limbs of affected dogs, which creeps up the central nervous system and can cause heart and organ failure, and subsequently death, if not caught and treated in time. 



Humans can be affected by heartworm, hookworm, tapeworm, roundworm and whipworm, from coming into contact with the parasites during different stages of the parasite’s development. This could be via touching contaminated soil containing worm casts, or from touching dog excrement containing worms, from dog saliva containing larvae. It is important therefore to medicate house pets against these endoparasites regularly, to stop the life cycle of these parasites completely. There are many products available on the market that kill these parasites (the term for them is “parasiticide”), some target specific parasites (e.g Advantix for ticks), while others claim to be broad-spectrum and kill many if not all known parasites (e.g Revolution). Some only kill adult parasites (e.g Capstar for dogs, which targets only adult fleas), others destroy the life cycle of the parasites (e.g Advantage for dogs, which kills adult as well as larvae fleas).

Revolution’s website contains a great table listing its effectiveness against ecto- and endoparasites, compared to several other leading brands.

Another parasite that can affect humans as well as dogs is Ringworm, which is not a worm at all, but a class of fungi called Dermatophytes. Ringworm in humans appear as circular, raised and itchy bumps resembling rings, hence the name. In dogs, Ringworm presents itself as bald patches, where the fungi has caused the hair shaft to break off. It may or may not be itchy. Here is a useful link showing photos of affected dogs and humans:


Coccidia and Giardia are 2 protozoal endoparasites that live in the bowel and cause bloat, cramps, diarrhoea and weight loss. Giardia causes mucousy diarrhoea, Coccidia causes watery diarrhoea. Because the Coccidia and Giardia protozoans are found in dirty water, it is easily transmitted to both dogs and humans. Humans can “catch” the diseases by ingesting the same infected water, or through contact with infected animals, or through contact with contaminated soil.

Diseases that can pass from animals to humans are termed “Zoonotic”. All the above ecto- and endoparasites and protozoal parasites are Zoonoses. The following link contains a list of many zoonotic diseases, not confined to just dogs but also to other livestock and primates:


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