ABC-Animal - Parasitology Chronicle

Myths and Facts on Zoonoses

Which statements do you think are True or False
Humans can catch certain parasites from animals. True or False ?
Animals can catch certain parasites from humans. True or False ?
Humans can transmit certain parasites to other humans. True or False ?
All of the above are true.

1) Transmission from Human to Human
We often think, wrongly, that people can only catch parasites from animals. But certain parasites commonly found in people are transmitted by other people, not from any animals, neither dogs nor cats.
Here are some examples.

* Pinworms (Enterobius vermicularis)
In North America, one third of children occasionally get pinworms, which are white roundworms measuring between 2 and 13 millimetres in length. During the night, these adult parasites stick their eggs to the skin of the buttocks, which causes a great deal of itching. When children scratch, the eggs get under their fingernails and on their hands and contaminate their environment, including toys and other people.

* Head lice (Pediculus capitis) or pubic lice (“crabs” or Phtirius inguinalis)
These fleas develop, reproduce and migrate from one person to another due to close contact. These lice can be found on animals temporarily, but they quickly die off. Animals have their own flea species, which cannot be transmitted to humans.

2) Transmission from Human to Animal
Humans can transmit certain parasites to animals and cause them to have health problems.

* Scabies (Sarcoptes scabiei hominis)
A human can infect a pet with scabies. This parasite is transmitted following direct and prolonged contact, which can cause an animal to develop a skin infection or dermatitis. Luckily it disappears in a few days if the contact stops or if the person is treated.

* Bedbugs (the most common is Cimex lectularius)
Infections with this parasite, which has been around since ancient times, have been increasing since the beginning of the 1980s. Active at night, bedbugs attack both animals and humans, but they normally only feed for a few minutes on an animal before leaving its fur.

So before accusing an animal of giving you parasites, think twice!

Alain Villeneuve, D.V.M., Ph. D.
Veterinarian, Professor of parasitology
Faculty of Veterinary Medecine, University of Montréal, Saint-Hyacinthe, Québec, Canada
Author of the book : « Les zoonoses parasitaires : l’infection chez les animaux et chez l’homme »
Edition : « Les Presses de l’Université de Montréal », 2003