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What is campylobacteriosis?

Visit us (http://www.khanacademy.org/science/healthcare-and-medicine) for health and medicine content or (http://www.khanacademy.org/test-prep/mcat) for MCAT related content. These videos do not provide medical advice and are for informational purposes only. The videos are not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of a qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read or seen in any Khan Academy video. Created by Jaffer Naqvi.

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Video transcript

- [Voiceover] So, campylobacteriosis is caused by a bacteria known as campylobacter jejuni, and it is the most common form of bacterial gastroenteritis in the developed world. So, many of the symptoms of gastroenteritis could include things like vomiting, dehydration, and diarrhea. But there are a few things that are distinctive of bacterial gastroenteritis. For example, the diarrhea tends to be bloody, and people may also experience some severe abdominal pain. Now, most forms of gastroenteritis typically last about a few days. But campylobacteriosis can last more than a week. It's possible that you can experience all these symptoms for about seven to 10 days. Now, how can you get this bacteria into your system? It's usually if you eat some kind of unprepared food. So, maybe you have some undercooked poultry. You can also get it if your drink some raw or unpasteurized milk and contaminated water. So, in general, things that haven't been cooked and prepared well. Once it's in your system, what exactly is it going to do? Well, here is a diagram of the wall of the small intestine. These green squares over here are the epithelial cells. They're going to be doing all the digesting and absorbing. What will happen is you'll actually have the bacteria come along and it'll actually try to invade those cells. So, let's look at this a little bit up-close. Here is our epithelial cell, and here is our bacteria. The bacteria is going to have this structure over here that kind of looks like a tail. We call this a flagellum. That flagellum is actually going to propel the bacteria. It's going to help this bacteria move into the epithelial cell. Once it's in the epithelial cell, it'll start to eat all of its nutrients, and that epithelial cell will begin to die off. Now, you have all these epithelial cells here that are just dying off. And remember that those epithelial cells are responsible for digestion and absorption. Because you can't digest food anymore, that stuff is just going to pass off as diarrhea. This diarrhea is going to contain all that food and all that water. Maybe it'll even contain some of those dead epithelial cells and maybe even some of the bacteria as well. In addition, you're going to have some immune cells over here, right? So, these immune cells will be triggered by that, that bacteria. And maybe those immune cells will get caught up in this diarrhea as well. Because of this, you start to experience those symptoms that I mentioned earlier, but there are actually a few more complications of campylobacteriosis that make it pretty unique compared to the other forms of gastroenteritis. Now, what are those complications? Well, here, I'm showing you a picture of a joint. This red structure is referred to as the joint capsule. And so, for our purposes, all we really need to know is that it has many different types of proteins here. When you have campylobacteriosis, remember that the immune system is trying to fight off that bacteria. In doing so, it's going to create antibodies against that bacteria. However, those antibodies will actually recognize some of the proteins in your joint capsule as well. Because of this, you're going to get all sorts of immune cells around your joints. And when this happen, we call this reactive arthritis. It's going to be very difficult and very painful to move around your joints. Now, this isn't the only complication that you may experience after having campylobacteriosis. So, here now, I'm going to show you a picture of the whole body. And about a few weeks after the person experiences all this gastroenteritis, they may start to experience some muscle weakness below their waist. Sometimes, that muscle weakness can be severe enough to be total paralysis. That muscle weakness and paralysis will start to move up from their lower extremities and into their chest. If it reaches their chest and if it's severe enough, the person may start to experience some respiratory failure. This whole condition that I'm talking about right now is called Guillain-Barre syndrome. So, what's happening? What's causing all of this to occur? Well, in your body, you have all sorts of neurons that are stimulating your muscle. The way they do this is by sending an electrical signal down the length of the structure known as the axon. The axon has this fatty-like substance that coats it, and we call this stuff myelin. The myelin basically helps that electrical signal move down the axon faster. Once again, remember that you have those immune cells, right, in your gastrointestinal system, that were making all of these antibodies. Like the proteins in the joint capsule, you have all these proteins and myelins that's recognized by those antibodies. You may even have some proteins on the axon itself that can be recognized by the antibodies. And, ultimately, you're going to get inflammation of all of these neurons. That inflammation is going to lead to a degradation of the myelin. Because there's degradation of the myelin, that electrical signal will move down the axon much more slowly, because remember that the myelin helps improve the speed at which that signal goes down the axon. Thus, your neurons won't really be able to stimulate your muscles as efficiently, hence why people start to experience this muscle weakness and paralysis. So, those are some complications that you can get after getting this type of gastroenteritis. Not everyone will experience this, and it's actually pretty uncommon. But it is something to be aware of. So, if you have some kind of gastroenteritis, and you want confirm if you have the bacteria in your system, what are you going to do? Well, like most forms of gastroenteritis, what you can do is you can go to a doctor and they'll take a stool sample. They'll send that stool sample off to a lab to see if they have the bacteria in your stools. And if you really want to be safe, you can also do some blood tests. We may look for things like low blood glucose that would indicate hypoglycemia, and high levels of sodium and creatinine that would indicate dehydration. These tests, like all other forms of gastroenteritis, are usually what doctors will do. And, of course, how can we treat it? Given that you're dehydrated, the best thing to do is to just drink a lot of fluids. There aren't really many medications that people use to kind of overcome campylobacteriosis. But if you really want to be safe and if you really want to prevent it, the best thing you can do is to just make sure you're cooking your food really well, because, remember that most people who have campylobacteriosis probably got it from eating some kind of uncooked or unprepared food or drinks.