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Asked by anon-256945 on 15 Jun 2020.
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Evelyn Greeves answered on 15 Jun 2020:
Interesting question. I study biology, so I can try and explain in a general way. I’m not an expert though!
Viruses are very strange things – they act like they’re alive, but they’re also kind of not. They have genetic material, like we do, and they can pass it on by making copies of it (a bit like we can pass on our genes by having children). However, they can only do this when they’re inside a living “host”, because they don’t have the machinery to make copies on their own. They have to borrow it from a living cell, which usually causes the cell to die. That’s why we don’t think of them as alive.
So because they need another cell to survive, viruses have evolved lots of strategies to make sure they do this really well. One big thing is that they generally don’t have much genetic material. They get most of what they need from the host. They only really need a few bits and pieces to make sure they can exit their current host cell and hijack another one! For example, the virus that causes flu has 8 genes (a unit of genetic information). Humans have 20,000 genes – that’s 2500 times as many!
So that’s why they can spread so far so fast – they don’t have to do much to replicate themselves and spread onto a new host. If you’re interested in find out more about viruses, a friend of mine made a very cool ‘interactive lecture’: http://viruspatterns.com/. He talks about some more tactics that viruses use to spread really fast!
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Anabel Martinez Lyons answered on 16 Jun 2020:
Evelyn has given a great answer already but I’ll just add to it here – the goal of a virus is twofold: 1) to infect a host cell and 2) to make more of itself. As Evelyn has said, there is debate whether viruses are in fact ‘alive’ because they lack the ability to replicate (make more of themselves) without help from a host cell, whereas all other living things we think of (plants, bacteria, animals, etc.) have the ability to replicate in one way or another. Viruses are extremely small structures composed of protein on the outside and genetic material on the inside; the protein outer layer allows it to bind to its desired host cell, and the genetic material allows it to give that host cell the genetic instructions to replicate itself (think of it as a genetic blueprint for how to make more virus). For every one cell a virus infects, it instructs that cell to manufacture the parts to make thousands more viruses. These newly made viruses end up killing the cell (typically), and then escape the cell to go on to infect and kill other cells in our body. This means that viruses are, by their nature, designed to spread and infect as far and fast as they can so that they don’t die out- hope that helps answer your question 🙂
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Luke Hillary answered on 16 Jun 2020:
There’s a lot of things that affect how fast viruses spread, like how infectious they are, how severe the symptoms are, how long they “survive” outside the body, and how many virus particles an infected person produces. If we compare SARS-CoV-2 to the virus that caused the original SARS, it’s less infectious and produces less severe symptoms. This means people can not know they’ve got the virus and are spreading it around for longer, meaning that is will spread faster. The way a virus infects is also important. Norovirus causes food poisoning and is really infectious. It’s also much more stable outside the body. However, because it can only be spread by the faecal-oral route (accidentally eating small quantities of poop from an infected person that they might have transferred by their hands after using the bathroom), it spreads in a much more localised way. You can’t get it by someone coughing near you, but can easily pick it up by touching contaminated surfaces.
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Melanie Krause answered on 16 Jun 2020:
Hi again Lago! 🙂
Not all viruses do actually spread very fast. That part is down to how people get infected. Viruses that spread through air like Polio or the new Coronavirus are most infectious because its easy to catch them. Other viruses like HIV are transmitted through blood so you can’t get it by talking to or hugging someone who has the virus and therefor it spreads a lot slower.
In terms of how so much virus is created in an infected person at once: That is also not the case with all viruses but the ones that are so quick have it quite easy because they get into a cell and turn it upside down so it does nothing but making more virus. In a way the virus is so quick at this because its very small and its easy for a cell to make a lot of it. Also the virus doesn’t care about keeping the other functions of the cell up and running so if the cell dies in the process thats fine for the virus. -
Aisling Ryan answered on 16 Jun 2020:
Hi lago P!
Viruses that infect our lungs are usually the ones that spread fast and far! This is because some viruses can simply travel out of our lungs when we exhale, and some will make us cough and sneeze so that they can shoot out of our nose or mouth and infect another person, which will keep the virus alive. Like everything on our planet, viruses want to stay alive as long as possible, and the only way they can do that is by infecting an animal or a human and living inside these animal/human cells. A different virus that also spreads very fast is chickenpox, but this can also spread by touching an infected person as its a virus that infects the skin, as well as the usual coughing and sneezing. The best way to stay safe from a virus that is spread through the air or on surfaces is to avoid touching your face and keep your hands clean 🙂 That way, unless you are in direct contact with a sick person, there is a much smaller chance of becoming infected.
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