The Story of Rabies

A reprint of my 2023 article, being moved to Substack

The Story of Rabies

A patient with a case of rabies came through my hospital this year. [The year was 2023]. Definitely not the kind of thing you see every day. Or even for most docs, once in a career. thought it would be good to review some basic facts about rabies, for my own sake as much as yours. It’s impossible to be up to date on everything in emergency medicine. The best we can hope for is continual study, revision, and learning.

So here goes: a brief intro to what you should know about rabies.

Firstly, there’s virtually no risk of person to person transmission. Worldwide almost all cases are from dog bites, though in somes places, rabies can be transmitted from bats, skunks, and raccoons too.

(Side note: If you ever are traveling abroad and wake up in a room with a bat in it (not a nice NZ, rabies-free bat though) go see your doctor. It’s theoretically possible to be exposed to rabies virus even if you don’t feel or see a bite.)

Worldwide we see the vast majority of cases and deaths come from India and southeast Asia. Some countries like New Zealand and Australia are rabies-free.

In this recent case the patient contracted rabies elsewhere and due to its prolonged incubation time, came down with serious symptoms in New Zealand.

Rabies comes into your body typically through an exposure to infected saliva, usually from a bite. The virus travels approximately 1 cm a day from the bite to your central nervous system, infecting your spinal cord and brain in something doctors call encephalomyelitis.

Patients typically present with a fever headache, neck stiffness, numbness and weakness of their arms and legs and eventually confusion, throat spasms, widespread paralysis, coma, and death.

Veterinarians and travellers to the endemic areas are at the highest risk. Once exposed you have some time to get the vaccine as well as the immunoglobulin (HRIG).

The rabies vaccine prompts your body to make antibodies against the rabies lyssavirus. This can take a while, up to a couple weeks, so in the meantime immunoglobulin is given. IG is pre-made antibodies to rabies, and it’s injected around the wound, so the virus can be neutralised and digested by the body’s immune cells.

Without these treatments the rabies virus typically cannot be stopped. Although the incubation period can take weeks (3-8 typically), once symptoms begin rabies is usually unstoppable, causing death typically within 10 or so days.

That’s even with expensive and modern ICU treatment. There are some protocols that put people in induced comas and treat them with antivirals, however the vast majority of even these maximally-treated people die.

The key then is to understand that if you’re travelling in a place that has lots of rabies, like India or Southeast Asia, that you don’t expose yourself to stray dogs and unnecessary rabies risk. And that if you are bitten or if potentially infected saliva comes into contact with your open skin or mucous membranes, you need to get to a medical centre that can give you rabies vaccine and rabies immunoglobulin promptly. I would not encourage anyone to waste more than a day or two getting to a medical centre that has the vaccine and immunoglobulin, if possible. Rabies has been successfully prophylaxed with treatment within 10 days, but on the other hand people have actually gotten encephalomyelitis within 9 days of an infected bite. And as I mentioned earlier, once the neurological symptoms begin, the patient has an extremely high chance of dying within the next 10 days.

If you know your risk is very high even before you go, let’s say due to your job, then you need to consider a pre-exposure vaccination against rabies a month before you leave.

There are an estimated 60,000 deaths every year due to rabies. Do not underestimate the risk posed by dogs, (especially stray dogs) in places (especially India and Southeast Asia) with endemic rabies.

And to wrap up with something even more interesting: hydrophobia.

Why do we say that rabies infected mammals like dogs or humans are frothing at the mouth and fearful of drinking water (hydrophobic)?

Perhaps it’s part of the brain injury that rabies causes: a delirium, sometimes with bizarre and aggressive behaviour. It could easily look, in old times, like a rabies-infected person is actually possessed by a demon.

But what if the fear of water is actually quite logical fear of the throat spasms that are especially associated with rabies virus infections?

What if patients are not fearful of water but fearful of the inevitable prolonged choking sensation they get when they try to eat or drink something and all of their throat constrictor muscles spasm?

Surely if you were already delirious, feeling like you were choking to death every time you drink would cause a great aversion to drinking. You might even become tremendously frightened when presented with a glass of drinking water, if you knew that the last 10 times this happened it felt like you were going to die from throat spasms.

If you combine this behaviour with confusion, agitation, and aggression, it’s easy to understand why in the old days rabies patients were thought to be possessed. The truth is, they were dying from a fatal virus.

Just as 60,000 people a year, worldwide, still are.

-Dr Gary Payinda