Of Rabies, Possums and Body Temperature!

Granted, this rabbit hole is somewhat unexpected, but you can thank one of my friends for pulling that thread and leaving me researching the topic for a couple of days. You might wonder why it took so long, well, buckle up and keep on reading!

It all started with a conversation about those little doors for cats and dogs, and the fact that if you are not careful and you live in the US, you might end up with a raccoon or a possum using said door and making themselves at home. Awkward guests!

Let's first dig a little into what rabies is.

Rabies is caused by Rabies lyssavirus, a neurotropic virus usually transmitted through the saliva of animals. The incubation period can vary but is usually one to three months in humans. The initial symptoms tends to be fever and headache and as the disease progresses an inflammation of the brain and meninges develops, which in turn results in symptoms such as slight or partial paralysis, anxiety, insomnia, confusion, agitation, paranoia, hallucinations. The person might also develop a fear of water.

The symptoms eventually progress to delirium and coma, and death usually occurs two to ten days after first symptoms. Survival is almost unknown once symptoms have presented, even with intensive care. Less than 20 cases of human survival from clinical rabies (meaning after symptoms appear) have been documented.

So, you get the idea: it is nasty, deadly and I would highly recommend against playing with rabid animals. If you are bitten, seek immediate treatment!

Now for the “even more scary” fact, rabies is reported in more than 150 countries and on all continents except Antarctica.

For some reasons, this makes me think that Antarctica is the right place to go in case of a zombie outbreak. Don’t ask, not sure why I associate rabies with zombies!

There is, however, one positive fact: rabies is almost exclusively present in mammals. The most common wild reservoirs in the United States are raccoons, skunks, bats, and foxes, but domestic mammals can also get infected (cats, cattle, dogs etc.). Even though rare, there has also been cases of rabies in bears (including one recorded polar bear in Canada!). In the UK, rabies seems to only be found in some bats!

Other animals can be infected with rabies, such as birds, reptiles or insects, but those have mostly occurred in laboratory conditions. There have also been studies that demonstrated that birds in the wild, while susceptible to being infected with rabies, usually remain asymptomatic, and some even develop antibodies.

Because no article is complete without a little bit of history, you should know that rabies has been known since around 2000 BC, with the first written record found in the Mesopotamian Codex of Eshnunna (c. 1930 BC), which dictates that the owner of a dog showing symptoms of rabies should take preventive measures against bites. In Ancient Greece (approximately 12th century BC to around 600 AD), rabies was supposed to be caused by Lyssa, the spirit of mad rage.

Now, getting back to the subject at hand, possums are one of the rare mammal exceptions. You will notice a lot of contradicting information online about whether a possum can contract rabies. The answer is yes, they can. However, this is an extremely rare occurrence because their body temperature is too low to host the rabies virus (as low at 94°F/35°C) and according to the Centers for Disease Control and Prevention (CDC), less than 1% of all reported rabies cases are in opossums. Normal temperatures for mammals range from 97°F to 104°F.

Other fun facts about those beautiful little creatures, possums rarely catch Lyme disease from tick bites, and are immune to the stings of honeybees and scorpions, botulism toxin, and snake venom.

Of course, I could not leave it at that, because while fish can’t catch rabies, there are still quite few marine mammals. This in turn led to the question: can a whale or a dolphin catch rabies?

The short answer is yes. That being said, there has been no record of a rabid whale (or dolphin) and only one documented case of rabies in a seal caught in Svalbard (Norwegian archipelago) in 1980. If you think about it, this makes sense, as the disease has been mostly prevalent on land, and the interaction between rabid coyote, foxes or raccoon and whales for example would be extremely rare. Nonetheless, it remains technically possible!

I am now waiting on a Hollywood movie about rabid whales or dolphins!

Sources: