Reverse zoonosis is a relatively new concept, and - as the term suggests - is the transmission of disease from human to animal.
We've heard a lot about this in the past few years.
Especially the fact that our pets can indeed catch the flu from us. Certain strains of influenza, most notably types H1N1 (also known as the swine flu) and H5N1, have been documented in dogs, cats, ferrets -- even a cheetah.
|The cheetah: one of several animals known |
to have caught disease from mankind.
Photo: Tom Rafferty
It's a virus. A norovirus, to be exact, in over half of the cases. Including mine.
(The remainder of all 'stomach flus' are caused by food-borne parasites or bacteria, according to the Centers for Disease Control - see link at bottom.)
So I began to wonder: do I need to worry about the cats getting this? Not only would it be terribly unpleasant for them, following around a vomiting cat all evening isn't much fun for me either!
Turns out there is cause for concern.
The first warning flag was when I learned that noroviruses belong to the virus family Caliciviridae. About now, any of you who work in a veterinary environment, or who volunteer or work in shelter environments are sitting up just a bit straighter, aren't you? I certainly did!
We see cats with calicivirus all the time. In fact, it's pretty contagious. Our shelter's policy is no free-roaming for any cat who's contracted the virus, since they can still "shed" it - meaning other cats can catch it - even after they're symptom-free. (They do eventually get their "get out of jail free" card back, in about a month.)
One of the staff at Wayside Waifs even joked with me about it, telling me I needed to carry around my own kennel card: "no roaming for 2 weeks"! That's the amount of time a human can continue to shed the stomach virus even after recovery. Oh joy, my husband says....
So norovirus is in the calici family, eh? I dug a bit further.
It seems several studies have been conducted since 2004 searching for indications that norovirus in humans is found in animals and vice versa. Then I came across this: in the January 27, 2010 edition of the magazine Veterinarian Microbiology, authors Koenig, Thiel and Wolf write:
"The close genetic relationship of noroviruses and sapoviruses found in animals and humans has raised the question whether these viruses have a zoonotic potential. ... Detection of human noroviruses in animals as well as simultaneous presence of animal and human viruses in bivalve molluscs suggest a risk of transmission. Furthermore, antibodies against animal noroviruses were detected in humans as well as antibodies against human noroviruses in swine."
No cases have been confirmed, but the above was cause enough for me to be extra careful around the felines in my family as well as the humans!
CDC on norovirus
Avian H5N1 influenza in cats, Science, October 2004.
2009 Confirmed results: H1N1, USDA.
Zoonotic aspects of infections with noroviruses and sapoviruses, Veterinary Microbiology, January 2010.
Noroviruses and Sapoviruses in man and farm animals, Deutche tierarztliche Wochenschrift, August, 2004.
Animal Noroviruses, Veterinary Journal, London, England, October, 2008.
I am not a veterinarian, and the information provided here is not intended in any way as a substitute for professional veterinary care. Nor should it be used to self-diagnose for your pet. This information is for educational purposes and to provide you with reputable documentation you can use to pose informed questions of your own to the veterinarian of your choice.