The Stomach Flu & Viruses of the Caliciviridae Virus Family

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  • 0:32 Caliciviridae…
  • 1:24 Norwalk Virus
  • 2:31 Stomach Flu in Cruises…
  • 3:33 How to Avoid Getting Sick
  • 4:20 Lesson Summary
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Lesson Transcript
Instructor: Artem Cheprasov

Artem has a doctor of veterinary medicine degree.

In this lesson, you'll learn about the most common cause of the stomach flu. We'll venture into the Caliciviridae virus family, its famous viruses, such as the Norwalk virus, as well as the diseases they cause.

The Caliciviridae Virus Family

If you've ever gotten the stomach flu, there's a really good chance that what caused it was a virus. If it was a virus, then there's a really good chance that it was a certain type of virus in the Caliciviridae virus family. What are not really good are all the nasty surprises that come with being infected by a nasty virus, which we'll get into in just a little bit.

Caliciviridae Structure and Transmission

Before we get to that, you should be aware that the viruses in the Caliciviridae virus family, known collectively as caliciviruses, have a positive-sense, single-stranded RNA genome and a small-sized icosahedral capsid that encloses this genome, and they are not enveloped. Some of the viruses in this family have cup-shaped depressions when looked at under the microscope.

The majority of viruses in this family are transmitted mainly by the orofecal route, although the respiratory route is also a possibility. Spread by the orofecal route means that these viruses will spread via surfaces or substances contaminated with fecal material that are then ingested by their victim. Regardless of how they are transmitted, they are very contagious.

The Norwalk Virus

In fact, because it is so contagious, the most common cause of viral gastroenteritis in the United States are viruses of the Norovirus genus. Norovirus is the genus of the Caliciviridae family. What that means is a family of viruses may contain one or more genera (the plural form of genus), while in turn, each genus may contain one or more species of virus. In fact, the species of virus most responsible for viral gastroenteritis in the United States is known as the Norwalk virus.

In case you haven't heard of the term, gastroenteritis is sometimes known as the stomach flu or food poisoning. This is where you get bouts of abdominal pain, diarrhea and vomiting due to the virus. Up to 90% of viral gastroenteritis outbreaks may be attributed to caliciviruses. However, do keep in mind that many other things from bacteria to toxins can easily cause the stomach flu as well; it doesn't always have to be a virus.

The Stomach Flu: Cruises and Schools

In any case, the reason this virus is named the Norwalk virus is because in October of 1968, an outbreak of viral gastroenteritis occurred in a school in Norwalk, Ohio. Half of the students and teachers developed signs of the stomach flu, and over one-third of those who came into contact with the affected people got sick as well. It wasn't until a few years later that the virus that caused this outbreak was identified and given the name Norwalk for the community it affected.

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