Sleeping with the Enemy

Do you sleep with your pets? I’m not talking hardcore bestiality here, but do you allow your pet to sleep on or in your bed? Do you? Who could blame you; they’re cute. They’re fluffy. They love you. In fact they love you so much they might even stop licking their Chocolate Starfish or genitalia for the briefest of moments to lick you instead. Ick!

If this picture sounds familiar you might be tempted to stop reading now, but before you do just ask yourself how you would feel if Fido gave you or your kids Bubonic Plague along with that big, slobbery canine kiss. Yes, that’s right not some poxy cat-scratch Bartonella, the Black Death. The same plague that killed about half of Europe in the 14th century. People can and have caught plague from their pets and on the admittedly rare occasions this happens it provokes quite a response; Yersinia remains a Category A potential bioterrorism agent – release it as an aerosol, an outbreak of pneumonic plague would follow and victims would present with symptoms resembling those of other severe respiratory infections. Except this spreads more rapidly and has a high mortality rate. (Classic Bubonic Plague doesn’t spread person-to-person so well but its pneumonic form does).

I’ll return to the Black Death in a minute – including the truly Pythonesque way it was catapulted into Europe – after a quick look at the more common pet-borne bugs (or zoonoses as we say in the biz)…

So Many Vermin…

The Fluffy Vermin and their ilk are a well-documented bridgehead offering Our Microbial Overlords an easy way to get at us and in us, and a review I read recently got me looking in to this subject – and getting Bubonic Plague from pets is far more common than you might think. And not just plague; lots of other really icky pet-borne bugs too. There’s a table at the end that shows which organisms you might give a free lunch to depending on your vermine duveteuse de choix. Enjoy!

In the UK about 25% of homes house the nation’s 9m dogs. And the 8m Fluffy Vermin Felis silvestris catus make 19% of UK households more likely to crash their car as well as transmitting infections a-plenty. Some limited data suggest 19% of dogs sleep in the bedroom and 14% on or in their owners’ beds, and the numbers are thought to be twice that for the Fluffy Vermin. In America more like 60% of households have pets and half sleep on or in the bed. The proportion of people who let their pets lick them (ick!) or who kiss their pets (double ick! with knobs on) is even greater. (Admittedly the data aren’t that robust but even if they’re out by 25% it’s still a huge number).

So Many Bugs…

Verminus duvetus f. ickiensis

The Usual Suspects

The Big 3 of Our Microbial Overlords loaned to us by the Fluffy Vermin are Bartonella, Capnocytophaga and Pasteurella.

Bartonella causes cat scratch fever (but is passed on via dogs too) where fleas and their poo carry Bartonella henselae. Then a scratch or bite from the Fluffy Vermin allows the Bartonella to get in and complications from what is normally a self-limiting, reasonably benign infection can include endocarditis, encephalitis and coma. And you don’t need a scratch – a lick is enough to get Bartonella well on its way to ruining your day.

Capnocytophaga is in the mouth of every dog and cat. If your immune system is OK this bug might just make your teeth fall out. If it isn’t an infection can be serious (like any bug if your immune system is screwed). There have been fatalities associated with pet-borne Capnocytophaga where the victims had allowed their pets to lick open wounds. Ick! In fact, Darwin Award level ick! or what?

Pasteurella loves jumping from Fluffy Vermin to their owners – and has caused meningitis in adults kissing dogs and in one study most cases of P. multocida meningitis in children were traced back to pets licking them. In one case a baby’s dummy had been used by the family cat as a plaything. Ick!

Rabies

Nowadays the principal reservoir in Europe, the US and Australia is bats – so you’re unlikely to get it from a domestic animal around here anymore. But there are still 25-50,000 cases worldwide, mostly in Africa and especially SE Asia and in many cases people had been licked by an infected dog, not bitten. Backpackers beware.

Staph

Cats and dogs carry Staphylococcus intermedius – one woman had a chronic middle ear infection with serious complications; turned out it was the same strain found in her dog’s saliva – the dog she allowed to lick her ears. Ick!  Another had a really nasty nasal infection with a foul discharge – which grew the same strain found in the bulldog she allowed to lick her face. Many animals carry MRSA, both domestic and wild. There was a case where a couple had serial MRSA infections traced to their dog who shared their bed and licked their faces. When the dog was autoclaved the infections stopped.

Credit: istrianet.org

The Black Death

The Big One. Yersinia pestis is the bug responsible for pneumonic, septicaemic and bubonic plagues. It has been responsible for epidemics throughout history – the Plague of Justinian, the Black Death and the 19th century’s Third Pandemic all are reckoned to have originated in rodent populations in China and all killed lots of people. Like really, really lots.

But the plague is still very much around: there are thousands of cases every year but until Yersinia becomes resistant aminoglycosides and quinolones render it far less deadly than in history. Yesinia pestis is also one of the most feared potential agents for bioterrorism and has an excellent track record in this regard: in the 14th century the Mongols’ Golden Horde under Jani Beg catapulted plague victims over the city walls while laying siege to Kaffa, a strategically important seaport on the Crimean Peninsula. Back to the 14th Century. In the summer of 1347 the Italian merchants whom the Mongols were besieging set sail from Kaffa for Italy thus bringing the Black Death to Europe. On the way they infected Constantinople, killing the Greek emperor’s son and lighting the touch paper for the devastation of Western Asia Minor as well as Europe.

Others…

I’ve written before about Toxoplasma making cat owners more likely to crash their car and in addition to the above there’s a host of zoonoses associated with Fido and Tiddles. Chagas disease, hookworms like Ancylostoma, roundworms such as Toxocara canis via dogs, Giardia, Cryptosporidium – and that’s without getting into more exotic pets.

Where does yours rank?

UK Pets and Our Microbial Overlords

UK Zoonoses 2003-12

These are laboratory-confirmed (i.e. proven) cases of zoonotic disease in humans, 2003-2012.