Friday, October 5, 2012

Rabies on the Brain

I’ve got rabies on the brain. Well, not literally, because that would mean I’d probably be dying in intensive care.
Last week (September 28) was World Rabies Day. It is the anniversary of the death of Louis Pasteur (more on him later).
Rabies is virus which causes a virtually 100% fatal neurologic disease in all mammals, including humans. According to “Rabies surveillance in the United States during 2011,” last year rabies was diagnosed in animals in 49 states (not Hawaii). Besides the “usual suspects” of bats, skunks, raccoons, foxes, dogs and cats, it was also diagnosed in cattle, horses, sheep, groundhogs, deer, beavers, otters, javelinas (shaggy piggy creatures), bison and alpaca. Bambi and Thumper could be rabid!
Rabies is spread by the saliva of a rabid animal. When the rabid animal bites a victim, it inoculates the virus into the tissues. Unlike most viruses and bacteria, which spread through the bloodstream, the rabies virus spreads along nerve cells. Depending on how far the bite wound is from the brain, symptoms might not develop for weeks to months to years. A person in the US died last year of rabies that was acquired from a dog in Brazil eight years previous! For eight years, the virus had been lazily moseying along, inexorably crawling up to the brain.
Once the virus hits the brain, bad things happen. Even in the 21st century, over 50,000 people worldwide die of rabies every year. It is a horrible death of alternating periods of lucidity and psychosis, pain, fever, convulsions, hallucinations and hydrophobia (pathologic fear of water).
I recently read Rabid: A Cultural History of the World’s Most Diabolical Virus, by writer Bill Wasik and veterinarian Monica Murphy. It’s a fascinating book, although I guess I might not qualify as a totally objective reviewer since I tend to get a little bit obsessed about public health and infectious diseases.
Wasik and Murphy weave together a history of rabies and civilization. Although many of the scary epidemic infectious diseases of humans, including Ebola, West Nile, SARS, swine flu, and hanta, are zoonotic (transmitted from animals), only rabies was known to be zoonotic before humanity ever considered the existence of bacteria and viruses. Think of bubonic plague (“The Black Death”): people didn’t realize it was caused by a bacterium spread by the bite of a rat flea. But rabies: slobbering psychotic dog bites human, human turns into slobbering psychotic animal. It was obvious even four millennia ago that rabies was transmitted by animals, particularly canines.
The book looks at theories, preventatives and “cures” over the millennia (the most effective preventative prior to vaccination was cauterizing the fresh bite with a red hot poker); history (St. Hubert is the healer of rabies sufferers); mythology (the slaver of Cerberus spreads both rabies and aconite); connections of rabies to werewolf and vampire legends; the handful of documented survivals of rabid humans; weird ideas that people have had to prevent rabies in dogs (one theory suggested rabies spontaneously arose in dogs due to sexual frustration and suggested prevention by creating “doggy bordellos”); rabies in various species (l’enfant du diable = the devil’s child, a skunk); history of canine mass killings in an attempt to stop epidemics; and a recent rabies epidemic on the supposedly rabies-free island of Bali.
The most fascinating chapter explains how Louis Pasteur developed the first rabies vaccine in the late 1800’s. In fifteen years of veterinary practice, I have never seen a case of rabies and hope I never do. Pasteur (who is also the father of pasteurization and food safety) was neither a physician nor a veterinarian, but was a really smart dude who was passionate about human and animal health.
You can’t grow rabies virus in a Petri dish. The only way Pasteur and his colleagues could grow rabies virus was by maintaining rabid animals in the lab, putting themselves at continual risk of gruesome death. At first they allowed a rabid animal to bite another to perpetuate the virus; then they started collecting saliva from slobbering aggressive dogs to inject into other animals. Eventually they hit on dicing up the central nervous system of a rabid rabbit and depositing it directly onto the dura mater of the recipient’s brain. By repeatedly transferring rabies directly from one rabbit’s brain to another they developed a highly virulent strain. The next step was to inactivate the virulent virus to make the vaccine strain, which they did by leaving the rabbit’s spinal cord out to air-dry for a few days. This air-dried infectious bunny brain was then injected as a vaccine: either a pre-exposure vaccine to prevent infection or a post-exposure vaccine to prevent development of symptoms after a bite.
The first human to receive the vaccine was a boy who had been mauled by a rabid dog. Can you imagine the agonizing wait for Pasteur to see if the boy survived or died? (He survived both the bite and the cure.)
We all learned in vet school that rabies is absolutely, guaranteed fatal. But some new research is showing it might not be completely 100% fatal. There was a girl in Wisconsin who survived clinical rabies after a medically-induced coma and months of rehab. And a recent paper was published in The American Journal of Tropical Medicine and Hygiene that looked at humans living in remote areas of Peru where vampire bats are a common carrier of rabies. 11% of the people had rabies neutralizing antibodies; they had not been vaccinated so those antibodies developed after infection with the real, live virus. How come they didn’t die? Has evolution favored people with a more exuberant immune system that can fight off endemic rabies?
However, despite this research, the odds of dying are still very, very high. Make sure your dogs, cats and ferrets are current on their rabies immunizations, and never approach an ill or strangely-behaving bat, skunk, raccoon or fox.


  1. Wow!!!' I had no idea that book existed until reading this post! I am a rabies fanatic (no pun intended) because I had to get post-exposure prophylaxis. I cannot wait to read this book! Thanks for mentioning World Rabies Day. (and I have seen rabies, in a raccoon. It was scary as all get out but fascinating).

  2. Vaccinate your horses and pet ruminants, too, please.

    "Rabid" was pretty good. It's full of cool rabies trivia.

  3. Of course, rabies is disease of (my favorite organ system) the nervous system.

    Never seen it myself, though. At least not in homo sapiens.

    My patients may be batshit crazy, but not dogbite crazy.

  4. From what I remember from vet school Prev Med, the human rabies titer levels we use to determine if we still have immunity from our rabies vaccines were derived from natural titer levels in North American/Canadian fur trappers. And, recent testing of wild raccoons in north-eastern states (I'm told) showed a relatively high prevalence of low levels of rabies antibodies. So, the theory exists that perhaps there are individuals within a population with immunity to rabies, or even the existence of less virulent strains of the rabies virus.

  5. Grumpy, be glad you have never seen it. Had to get shots (BTW they are in the ARM now, not the stomach!) because cat at shelter where I volunteered turned out to have the disease.
    Yes, the cat bit me, and that is what made us wonder about him. He was (until then) very sweet and docile and had had a rabies vaccination when he came in. But in a matter of days he turned into Dracu-Cat! I thank God every day that he didn't go home to a family w/ kids.
    Being then a reporter, I did interviews with vets and public health folks. Just trust me, you never want to see it or Dx it.

  6. I'm here in San Francisco and a local person recently died of rabies probably contracted after he handled a bat last March

  7. Sounds like a fascinating read. Do you have any other good books in the same vein? (epidemic infectious diseases) I just finished a reread of Hot Zone and read Fever 1793 and Flu for the first time. Soooooo interesting!

  8. Claire--Another fascinating one is Deadly Feasts about prion diseases like BSE and kuru.

  9. I was bit by a mouse when I was five and had to have the series - 14 shots in my stomach.

    I hate mice.

  10. The Ghost Map- Steven Johnson is another good book in the same vein.

  11. I have a whole section on rabies in my zoonosis lecture that I give MDs. I generally stick with internal med and family practice docs, though I think that emergency docs should probably get the lecture too. After seeing what a charlie foxtrot most animal bite cases tend to be around here (almost no MD mentions rabies to people and when it is pointed out, they don't understand the rational behind vaccination after being bitten nor do they understand WHERE the vaccine should be given). There is just so much for them to remember, that since we are relatively "rabies free," it is low on the list of things to know.

    1. I have an human ER doc friend that actually came to me to discuss putting together a lecture (possibly series) of "What Every DVM Wants Every MD/DO Knew" We talked a lot about rabies, blastomycosis, and leptospirosis - all very common in WI where I live, but the human docs don't look for them or misdiagnose them regularly. It is craziness!

  12. Thanks for posting this. this is very alarming. i think i have to speak with my dog bite attorneys that could definitely explain to me the best resort.