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What is viral gastroenteritis?

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] Gastroenteritis is often referred to as the stomach virus. If you've ever had the stomach virus, then you'll probably know some of the symptoms associated with it. These include diarrhea, vomiting and nausea, and dehydration. What exactly is causing all these symptoms? I think the word stomach virus can give us a good hint. Sometimes, gastroenteritis can be caused by a bacteria, but, for the most part, it's caused by some kind of virus, and there are really many types of viruses that can do this. Some examples could include the adeno virus, the sapa virus, the rota virus, the noro virus, and the astro virus. A lot of different viruses can cause gastroenteritis, and this is really just a handful of them. How do we know if the infection is viral or bacterial? For one, if you have a viral infection, your diarrhea tends to be watery, whereas if you have a bacterial infection, it's more likely gonna be bloody. In addition to that, people with bacterial gastroenteritis will experience more fevers. Now, I don't want to be completely absolute here, sometimes there are exceptions where a bacterial infection can cause watery diarrhea, but, in general, this is the pattern to look out for. How did the virus get into your system to begin with? It's usually through fecal to oral transmission. The feces of someone who has gastroenteritis will be contaminated with the virus. Let's say you know someone who has the disease and they use the bathroom. They don't wash their hands very well, right? Because they don't wash their hands very well, their hands have some of the pathogen on them. Then, maybe they go on to touch something, like food or water, and then you may touch the same stuff, so then maybe you'd have some of the pathogen on your hands. Then, if you give the virus access to your mouth, you can get infected. Once it's in your system, what exactly is it going to do? Well, let's take a look at the gastrointestinal tract. Along your gastrointestinal tract, you actually have this wall that kind of lines it. This wall goes over your stomach, your small intestines, so on, and so forth. We call this the gastrointestinal wall. I actually wanna zoom in a little bit more on this wall. You can see here, there are many different layers. I wanna focus on this green layer over here. This layer is called the epithelium. It contains all the cells that will be responsible for digesting and absorbing nutrients and water. The viruses are going to invade the epithelium. Why don't we zoom in on one of the cells in the epithelium? This is our epithelial cell. It'll perform a lot of really important functions, like digesting and absorbing. Let's say this cell encounters a virus. First of all, what is this virus made of? First, we have this kind of capsid structure over here, and it's really just made out of proteins. Within this capsid, you have some kind of nucleic acids. This can include DNA or RNA. That virus really wants to replicate, but it lacks the enzymes necessary to do this, so how is it going to do that? This cell has all of the machinery necessary to do just that. It has all the enzymes that can make more viral protein and more viral nucleic acids, so the virus is actually going to invade this epithelial cell, and in doing so, it's literally going to hijack it, so you'd have all these enzymes in here. These enzymes will be responsible for synthesizing things like DNA and proteins, so the virus is going to make use of those enzymes. Now, all of a sudden, you get all these viral proteins. You're also gonna get a lot of viral nucleic acids as well. These are then going to come together, and they're going to form new viruses. The viruses can then leave the cell, then go on to infect more epithelial cells. Basically, what you have is a cell that's just been turned into a virus making factory. In addition to that, the virus is actually going to shut down many of the functions of the epithelial cell. Maybe it'll release some toxins that can do a lot of damage to the epithelial cell, so, for example, it'll stop the epithelial cell from absorbing water. It can also deactivate certain proteins on the intestinal gut lining that are responsible for digesting your food. All in all, it really stops the epithelial cell from doing what it needs to do, and it just turns it into a virus making factory. Let's say that you have viral gastroenteritis and you want to visit the doctor. What might the doctor do? They might order a few stool samples, just to evaluate whether or not the pathogen is a virus, because, remember that the feces are contaminated with the pathogen. They could also run a few blood tests, mostly just to see if the person is dehydrated. The way to see that is if the person has high levels of sodium or creatinine in their blood. Once the doctor has completed all these tests and they've confirmed that you have viral gastroenteritis, what can you do? Usually, the symptoms last from a few days to about a week, so there really isn't much medication that people can take if they have viral gastroenteritis. Antibiotics will not actually be helpful in this case because they only target bacteria. They do not target viruses. Because of that, it's not really useful to give the person antibiotics. However, if you wanna treat those symptoms, one of the best things you could do is drink a lot of fluids. Drink a lot of water, drink a lot of fluids with salt and sugar in them, to really overcome a lot of that dehydration that you may encounter. These are some pretty significant ways to diagnose and treat viral gastroenteritis. To ensure that you don't get the virus, the best thing to do is to just practice good hygiene. Always wash your hands, always cook food properly, drink decontaminated water, and so on, and so forth. There's actually one more thing that we can do to potentially prevent getting gastroenteritis. That would be getting a vaccination. When we give someone a vaccination, we give them a weaker version of the virus. This is called a live attenuated virus, so when you inject it into someone, it's not really gonna cause any of the symptoms. It's pretty weak and it's pretty benign, but what it will do is it'll actually prep the immune system. The immune system may come along, and it'll actually recognize this virus. It basically just says, "Okay, we've seen this virus, "and now we know what it looks like, "so that when the real thing comes along, "we can stop it right away, before it starts "to cause any symptoms." One thing to keep in mind is that we have a vaccination available for the rota virus. This vaccination is available in a lot of different countries, so wherever it's available the rota virus isn't really as much of a problem in those countries. In fact, this vaccination is so important because it saved thousands of lives.