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People have been scared of rabies for thousands of years, many times depicting their fear
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in drawings and carvings of menacing dogs.
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But rabies is scary for more reasons than just a painful bite.
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Because once the virus is inside us, it not only destroys our body, but damages our mind,
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and it can happen fast, or lay dormant for years before fatally attacking.
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So how exactly do we get from a dog bite to a complete behavioral change to...death?
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The virus that causes rabies is spread through saliva, so the most common way to contract
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rabies is through an animal bite, most likely from a dog, bat, raccoon, skunk or fox.
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There have been a few, rare cases of transmission through infected organ donors and an even
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rarer instance of a lab accident, but for the most part it comes down to a bite from a rabid animal.
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So even though it's a virus that can infect and kill humans, it's studied considerably in veterinary labs.
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OK.
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I am Dr. Susan Moore.
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I'm the laboratory director of the rabies laboratory at Kansas State University, part
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of the veterinary diagnostic lab within the vet school here.
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We are the largest rabies serology laboratory in the world.
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So the rabies virus is in the family lyssavirus,
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lyssa means rage really.
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So that kind of tells you what this group of viruses are capable of.
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And what they're capable of is causing a very quick and painful death caused by the
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virus making its way into your brain.
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It's a neurotropic virus.
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So that means it's preferentially going to infect neural tissue or neural cells.
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So when it gets injected into the skin or the muscle, it's not going to replicate all
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that well but all it needs to do is replicate enough that it can get to that neuromuscular
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junction where that it can go from the muscle cells into the central nervous system.
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Now, at this point you'd think your immune system would kick in, recognize this dangerous intruder and destroy it.
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But, your immune system doesn't see it.
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This is thought to be because the virus replicates slowly in the muscle tissue, slow enough not to cause any alarm.
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This gives it a chance to reach the nervous system, where it hitches a ride up to the
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brain and slips through the blood brain barrier.
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It's behind this shield where the rabies virus can flourish while still being able
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to hide from our immune system, because the blood brain barrier evolved to keep dangerous or harmful things out.
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But sometimes that includes immune cells.
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In fact, if T cells do get past the blood brain barrier, the rabies virus has evasion
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techniques where it actually kills the T cells that are coming in.
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As the virus replicates in the brain, it starts to mess with the brain's cellular proteins, causing neural dysfunction.
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This is where certain symptoms of rabies start and how you can tell the infection has fully set in.
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Once the infection has fully set in, it will start traveling back out through the nerves into innervated organs, hair follicles.
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But again, particularly through to the salivary glands.
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So that it could be transmitted out.
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These neurological symptoms also help the virus transfer to a new host.
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Hypersalivation ensures there is enough rabies-infected saliva in the optimal transmission location, your mouth.
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And hydrophobia, or trouble swallowing, ensures that it stays there.
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In animals, the aggression can result in an attack on another animal or a human.
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Put all three of those together and you have a very effective way to ensure the rabies virus is passed on.
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Saliva is the way that rabies is transmitted.
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The way the virus is adapted, it is not in blood.
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It's not in body fluids.
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So it has to find a way to be transmitted effectively, right, to perpetuate its existence.
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Now, this neurological damage caused by the infection is the thing that finally tips off the immune system.
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However, at this point it's too late.
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Even though your immune system is finally going after the virus, it has already spread throughout the body.
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After that you have to remember this period is pretty short.
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There's just a couple days because then it'll progress into a coma and then death which
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is usually due to some kind of organ failure.
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But a bite from a rabid animal doesn't always mean certain death.
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People who have been exposed to the rabies virus can get a series of shots that can boost
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the immune system and fight off the virus, you just need to get to it before it reaches the brain.
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So surviving rabies is all about timing and the location where you get bit.
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Where you get bit.
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It plays a big role.
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So since the virus has to travel through the nerve system, the closer, and get to the brain,
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the closer that bite is to the brain, the better for the virus.
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Bats are a danger for that reason that it's going to be biting probably around
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your head or your hands. But also you don't notice a bat bite because the teeth are so small
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and they are so small.
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Maybe.
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You have a bat on your shoulder and you don't know it.
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You just looked on your shoulder, didn't you?