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HomeSurvivalHealth, Hygiene, Illness, Injury

Rabies - A Layman's Explanation

by Mike Pedde

What is it?

Rabies is a disease spread through a virus. Basically, viruses work like this. Most cells have both DNA (deoxyribonucleic acid), and RNA (ribonucleic acid). These are the genetic coding, the building blocks of life. When cells divide, the genetic information is copied and transferred to each cell. Viruses are one-celled creatures that have only one or the other. Rabies is an RNA virus. Rabies virus belongs to a group called Rhabdoviruses, which are bullet-shaped viruses with a hard sheath. Viruses are incapable of dividing or reproducing on their own, so they use other cells to do this for them. A virus will attach itself to another cell, such as a blood cell, and inject its genetic coding into the cell. This changes what the cell does, from being a red blood cell or a liver cell to becoming a little virus factory. The virus repeats itself inside the cell over and over until the cell literally breaks open, and all these little viruses go out and attach themselves to other cells.

Incidentally, this is one of the reasons why there’s nothing you can take to cure a cold. There are a lot of different versions of the cold virus (viruses mutate readily), and because the virus attacks inside the cell, there is no way for any medicine to reach it. By allowing yourself to rest, your body’s own defenses (white blood cells) can attack the viruses. By drinking plenty of fluids, you eliminate these dead white blood cells and viruses from your system. Diseases like the cold virus are called opportunistic pathogens. What that means is that these viruses ‘n’ things are always present in the air and on surfaces around us, but most of the time our bodies are able to ward them off. It’s when we allow our defenses to get depressed through not eating properly, not getting enough rest, having too much stress, etc. that the virus can get a start.

There are four levels of damage that viruses can do. Level one viruses are things that don’t cause many problems, like the cold virus. Level two viruses are things that are more serious, but not usually fatal, like polio or hepatitis. Level three viruses are fatal to humans, but ones where there is a way of dealing with them. Rabies is considered a level three virus. Level four viruses are those that are fatal, and for which there is no way of dealing with them. Ebola is considered a level four virus. During the black plague of the Middle Ages, there was about a 40% death rate. Ebola Zaire has over a 90% death rate, and it’s highly contagious. There are level four biocontainment labs at USAMRIID (the U.S. Military) and at the Center for Disease Control in Atlanta, for example. To work with level four viruses, you have to be in a space suit type apparatus, and the rooms where these viruses are kept have a negative airflow. What that means is that if you blew a hole in the roof, air would flow in, not out. It’s not something you want to mess with. With Ebola, the skin and muscle tissue essentially liquefies.

  

Where Does Rabies Come From?

Rabies virus has been around for a long, long, long time. There are writings about rabies from Mesopotamia, and on the hieroglyphics in Egypt. In North America it is thought (but not proven) that the virus came with the explorers from Europe, traveling in sled dogs and pack animals. In northern Canada, rabies was historically known as arctic madness or Eskimo sled dog disease. It was diagnosed as rabies in the 1920’s. In the late 1940’s rabies spread from arctic foxes to red foxes, high in northern Ontario. From there it spread down into southern Ontario fairly quickly. The open farmland provided excellent habitat for foxes, and thus for rabies. Traditionally, Ontario has had the highest incidence of rabies anywhere in Canada, although there are occasional outbreaks in Quebec and there is some skunk rabies in Alberta.

  

How Do Viruses Spread?

Most viruses spread from individual to individual through the air or through inter-surface contact. Within the body, most viruses travel through the bloodstream. Rabies virus is an exception in that it only travels within the body through nerve cells. Once the virus has access to a nerve cell, it will travel along the peripheral nerves to the spinal column, then along the spinal column to the brain. Once it has a good stronghold in the brain, it will spread fairly quickly throughout the whole body. One of the places it goes is to the salivary glands. There, the virus transfers what the salivary glands do (making saliva so you can chew and swallow your food) to becoming little virus factories. It is often said that a rabid animal foams at the mouth. This is because the animal is producing a lot of saliva, and the saliva has rabies virus in it. The virus also changes the animal’s behaviour so that a rabid animal will bite at anything. They’ll bite at rocks, at sticks, at trees, themselves, and anything in their path. This is how the virus ensures its spread from one individual to another.

There are four ways to contract rabies:

  
Saliva. Because there is a lot of virus in the saliva of a rabid animal, salivary contact is the most prominent way of spreading rabies. This is mostly, BUT NOT EXCLUSIVELY from a bite or scratch from a rabid animal. It’s vital to remember that saliva is the agent of transmission. Let’s say a rabid fox comes into the yard and gets into a fight with your dog. The dog kills the fox, and you tend the dog. From the fight, the dog has saliva from the fox on its coat. By handling the dog, you transfer some of that saliva to your hand. If you have a cut or lesion on your hand, it might be possible for the virus to gain access to a peripheral nerve. Let’s say you have no cuts or contusions. Are you safe? Maybe, until you rub your eye with that hand. How about that barn cat that licks you? Working in the rabies necropsy lab, one of the most difficult things is to find something to scratch your nose with.

  

Rabid Meat. Because an animal that died from rabies would have a lot of virus in its system, it would be possible to get rabies from handling an infected animal. Cooking would of course kill the virus, but let’s say a wolf found a carcass. If the meat made it into the stomach, the acids would kill the virus also, but if the wolf had a cut on its lip, a lesion on the throat, or anywhere the virus could get access to a nerve, it is possible to contract rabies that way.
  
Aerosol. In some specific cases, in bat caves where there are a lot of bats and a lot of guano on the floor of the cave, where there is a lot of humidity and a warm moist air column, it is possible to get rabies by breathing it in.
  
Vertical Transmission. This is a fancy term that means transferring the virus from parent to offspring. I did read a report that talked about possible genetic transfer of rabies in the Mexican Free-Tailed bat, but mostly scientists aren’t sure whether the virus is transferred from the mother licking the young to keep them clean. Here you’re back to saliva.
  

What Does a Rabid Animal Look Like?

Depending on where the virus contacts the body, it can take more or less time for symptoms to develop. The face is a lot closer to the brain than the foot. It’s important to remember that even with a bite wound, the virus must contact a nerve cell in order to proliferate. If the virus can’t contact a nerve, it will die within a short period of time. Before Pasteur developed the first rabies vaccine, about 40% of people attacked by rabid animals developed the disease. It’s not something you want to take a chance on. Normal gestation (from point of contact to symptoms) of the virus usually takes about three weeks. However, there have been cases where the virus has taken up to two years to become active. It is vital to take action quickly, as once symptoms develop the virus has taken over the brain. There have been a couple of cases of humans who have survived rabies, but they had virtually no cognitive function (a "vegetable").

There are generally acknowledged to be two forms of rabies, the fierce form and the dumb form. Often one is the progression of the other. Once the animal begins to display symptoms, it has at most five days to live, often a day or less. There have been a few cases where an animal was shedding virus through the saliva but not showing symptoms and vice versa, but most often these begin around the same time. A raccoon that panhandles in a park is not showing signs of rabies, even if it displays mild aggression. A rabid animal will wander around as if drunk. Paralysis develops in the hips, so often the animals will have difficulty walking, staggering around. It will attack or bite at anything, unprovoked. With cattle, they often bellow and seem agitated. Cats are more likely to become fierce. As the disease progresses, there is a swelling in the throat that compresses the trachea. Eventually the animal is unable to move or breathe and it asphyxiates.

  

What Animals Carry Rabies?

ANY mammal, any animal with hair or fur, can contract rabies. This includes humans. One question children have asked me a lot is, "Can whales get rabies?" Technically, yes. However, it’s unlikely a rabid animal would get close enough to a whale to spread the virus.

The animal that is the dominant carrier of the virus in a region generally classifies rabies as the type for that region. For example you have coyote rabies in Texas, the Mississippi skunk strain, and raccoon rabies and fox rabies here in Ontario. It is vital to note that any mammal can get any kind of rabies. These species are the dominant carrier of that type, mostly because they are most likely to be in contact with animals of the same species. The raccoon strain is particularly virulent, affecting a wide variety of species quite readily. Historically, we have had fox rabies in Ontario. Raccoons and coyotes have been a little more resistant to that strain of rabies, but virtually all skunks in Ontario that have had rabies were infected by the fox strain. On the grossest level, it’s all rabies virus. Using fancy PCR techniques, you could separate fox rabies from Windsor from fox rabies from Ottawa.

Fish don’t get rabies; neither do insects, reptiles, amphibians or birds. Having said that, there was one case of a young owl in France that contracted rabies. It is the only known case in history. Some species of raptors, especially Great-Horned Owls have been known to be carriers of the virus in their bloodstream because of predation on skunks. Their internal body temperature is too high for the virus to spread so they don’t contract the disease, nor do they spread it.

In Ontario, the main rabies vector (until the past few years) has always been the red fox. Ever since rabies moved into southern Ontario in the 1950’s, Ontario has had the dubious honour of having the highest incidence of rabies in Canada. Because an outbreak of rabies can kill most of the animals of a given species in an area fairly quickly, it takes time for the population of animals (and rabies) to rebuild. Rabies in Ontario generally runs on a four-year cycle of diminish and rebuild until the next outbreak.

In 1967, a stray cat scratched a little girl near Ottawa and she died of rabies. That was the last fatal human rabies case in Ontario. It also marked the beginning of the Ontario Ministry of Natural Resources Rabies Research program. Over the years the Rabies Unit developed a strategy to deal with rabies using bait containing a rabies vaccine. The project has included a number of agencies, both public and private. It remains a co-operative project. After several years of doing small-scale projects, the Rabies Unit began a large-scale project in eastern Ontario in 1989. The area from Ottawa to Brockville had a very defined rabies cycle, with very obvious patterns of highs and lows. There was an average of 400 cases per year in that zone. They began large-scale baiting in 1989, and the last rabid fox in that area was in 1993.

Raccoon rabies in the U.S. was traditionally confined to Florida, Georgia, Louisiana and the southern part of South Carolina. Over twenty years ago, a group of raccoon hunters from West Virginia who had shot all the raccoons in their area went down to Florida, loaded up 3500 raccoons, and released them in West Virginia. Raccoon rabies came too, found a susceptible population and exploded up the Eastern Seaboard. It is now found along the entire East Coast, and is continuing to move north and west. The first cases in New York State were in the southeastern corner of the state in the early 1990’s. The disease spread like wildfire through the state, and approached the Canadian border first in the Niagara region. Because the vaccine in the bait we developed was designed for foxes, it would not work on raccoons. Therefore, the Rabies Unit began an intensive program of live trap - vaccinate and release (TVR), using cage traps to capture the animals and Imrab vaccine (the same one your vet uses) administered by injection. As the disease moved east along the southern shore of Lake Ontario, the Unit began a similar program around the bridgeheads at Gananoque, Prescott, and Cornwall. A vaccine bait combination has since been developed for raccoons as well.

There are two problems associated with raccoon rabies that aren’t as prevalent with fox rabies. One is that raccoons are great hitchhikers. Raccoons have been known to catch a ride on transport trucks, boat trailers, and trains. The other problem is that they live close to humans, and humans tend to think they’re cute. When raccoon rabies first entered New York State, there was a raccoon rehabilitator who wanted to take some raccoons five counties west from an epizootic area, and release them in a county where the rabies had not yet progressed. He was caught by the New York State Troopers and sent home. He then went on the local radio station, proclaiming himself some sort of raccoon vigilante, saying that he was going underground and the authorities couldn’t stop him from releasing those animals. We had at least one known case in Ontario where a man live-trapped a raccoon in his backyard in Toronto, but didn’t want to kill it. So, he took it to his cottage three hours away and released it. The first cases of raccoon rabies in Maryland were fifty miles over the border, near a garbage dump. The first case of raccoon rabies in Ontario was some 50 kilometres north of Brockville in a well-known raccoon "dumping zone" for the city. There are wooded parks in Toronto that have up to 100 raccoons per square kilometre! A lot of humans mean a lot of garbage, and to raccoons that means a lot of food.

A note about relocation and bounties: First, the Rabies Unit did an experiment where several raccoons were live-trapped in Toronto and released in the country north of the city. Farmland, an idyllic situation… All the released animals were dead within three months. Because there is such a high population of raccoons already, the released animals were unable to find a home range. Some were hit by cars; others starved to death. Second, nature hates a vacuum; if you remove a lot of animals from an area, either by poisoning, bounty or relocation, you encourage other animals from outside the area to immigrate to fill the void. They bring with them their own diseases, parasites, etc. Over the past hundred years or more, coyotes have been shot, trapped, poisoned, exploded, and there are more now than there were then. Finally, if you relocate an animal, you also relocate any diseases it may be carrying.

As our urban areas continue to expand and chew up more and more habitat, human/animal interactions are more and more common. This is especially true of the people who buy houses with those nice ravine lots at the back. These are the people who call every day to complain about the wildlife in "their" back yard.

  

Dealing with Rabies

It must be noted that there is no known "cure" for rabies. For people such as myself who work around rabid animals there is a pre-exposure inoculation to raise the body’s ability to deal with casual contact. For anyone who has been in contact with a rabid animal there is a post-exposure treatment. Anyone who had rabies shots 30 years ago will be pleased to know that the treatment has changed. The original rabies treatment (the Semple treatment) consisted of autoclaved brain tissue (steam "cooked" to sterilize) that was injected directly into the abdomen. There was no way to get it absorbed into the bloodstream directly, so it had to be absorbed through the intestinal wall. After the required shots, the whole abdomen turned into a huge red welt.

That system hasn’t been used for some time. Post-exposure treatment now consists of five shots in the arm over a period of a month, plus one hemoglobin shot to boost the immune system.

Now, only a doctor is qualified to give medical advice, and only a doctor can prescribe post exposure treatment. If you are in contact with a suspected rabid animal, try to save the specimen if possible, especially the head. The brain will be sent to the Agriculture Canada Rabies Lab for testing. The first thing you can do is to wash the contacted area with soap and water, then contact your physician or the local emergency ward. If a pet has been in contact with a potential rabid animal, the same applies. Take cautions with the animal, and contact your vet as soon as possible. If it is a pet contact and the attacking animal is confirmed rabid (or if it escapes), the vet will likely recommend complete quarantine or euthanasia.

If you come across a dead animal on your property and there is no possibility of contact from anyone or any pet, then either wrap it well in several garbage bags (turn the bag inside out, then envelop the animal) and/or bury it deep enough that it won’t be dug up. If you must handle the animal, use a shovel or, if absolutely necessary, use heavy rubber gloves. Use a bleach solution to disinfect everything.

If you find a dead animal on your property or a road-killed animal, the question becomes, "Is it still rabid?" It depends on two factors: time and temperature. Temperature is the more important factor. There is an old trappers’ saying that if you find an animal you suspect to be rabid, you should freeze it before handling. Absolutely the worst thing you can do. Freezing does not kill rabies virus. The virus will go into a suspended state, only to awaken on thawing. An Agriculture Canada experiment put a rabid animal in a freezer at -30 deg. C for two years. When the carcass was thawed, the virus was still active! Rabies virus in a petrie dish at room temperature will remain active for a few days. In a summer, roadside condition, the virus around the surface of the animal would probably die within half an hour, but the virus in the brain would be viable for several days. There is no way to guarantee that any dead animal did or did not have rabies without a brain test. During the rabies enzootic experiment in eastern Ontario, about 50% of the road-killed foxes we received were rabid! About the same percentage of animals with quills were rabid. Several animals with quills were young and likely very hungry; one was 10 years old (Methuselah for foxes). Many road kills were also young and inexperienced. Better to err on the side of caution.

If you find a dead animal that you want to skin, especially if you want the skull for a sample, be VERY careful. Remember that rabies can be fatal, but it is not the ONLY disease or condition out there. Some of them are transferable to humans. Wear rubber gloves and a rubber apron. Wear eye protection and a kevlar glove on the hand not holding the knife. Disinfect everything with a bleach solution. If you prick yourself with a knife or bone, contact your doctor. Use common sense. At this time, raccoon rabies is confined to eastern and central Ontario. Fox rabies is still present in small amounts in pockets around the southern part of the province. Remember that other species of mammals can also get rabies.

 

  
Here are some actual cases of rabies contacts:
  

Several hydro workers found a fawn staggering along a hydro right of way. They thought it looked sick, and so took it home to care for it. Fourteen people received rabies shots.

A deer study crew discovered a dead deer lying in a stream. It had been partially eaten by wolves and marten. The crew poked and prodded the body before one of them wondered if maybe it was rabid. They all received rabies shots.

Near Ottawa, someone found a fox on the side of the road and cut the tail off. Someone subsequently had the animal tested, and there was a public service announcement on the local radio stations urging the person who had removed the tail to contact their doctor as the fox was rabid.

The last fatal human rabies case in Canada was a young man in B.C. who was attacked by a rabid bat while he was out hiking. After his death it was discovered he was rather promiscuous and so several young women in Alberta and B.C. had to be vaccinated.

A farmer discovered a fox having a fight with his dog, so he shot the fox. The children had never seen a fox before, so he brought it into the house and laid it out on the kitchen table. The entire family received rabies shots.

There have been a few cases of rabid bears in Ontario. One was shot in the southwestern part of the province after it killed a couple of dogs and chased a couple on an ATV. After being shot it was discovered that the bear had a mouth full of quills and had been chewing on its left forepaw.

At a natural resources college, someone brought in 11 foxes for the students to skin and necropsy. The entire class had to be vaccinated.

In New Hampshire, there was a pet store that was frequented by local school kids. Some of the animals were loose in the store, and people were encouraged to give them attention. People were also allowed to take a pet home to try it out before buying. One day someone brought in 8 kittens from a barn, two of which had contracted rabies. Over 600 people had to get rabies shots from that one case.

  

The bottom line is not to scare you out of the woods (!), but to make you aware that there are things out there that can be dangerous.  Use caution where appropriate.