Karen Bacon answered on 12 Nov 2013:
Flu is an airborne virus that we spread between us through coughing and sneezing. The virus is in the air and if you are near someone who is coughing out flu virus then you might breath it in. You can also pick up flu from nasal secretions or surfaces where people have coughed, sneezed or rubbed their nose! You can also catch flu by shaking hands with someone who has flu – this is one reason that you should wash you hands!
Once the virus gets inside a new host (ie you) it will attack living cells. Flu viruses have two big glycoproteins on their outside. Hemagglutinin helps the flu virus bind to the target cell lets the virus insert its genetic material into the cell. This is how your cells become infected with the flu virus. Once inside a living cell, the virus will replicate, making more flu viruses. The second glycoprotein, Neuraminidase, cuts proteins that bind the new flu viruses in the cell and allows them to escape in order to infect more cells. This is how the virus spreads inside a host and makes people sick.
Sofia Franco answered on 13 Nov 2013:
Karen has pretty much covered the scientific part of it! In a quick explanation, basically the flu is caused by a virus… when you get the virus, it will start multiplying inside your body and your immune systems starts fighting it, trying to prevent it from infecting you more….in this process you get weaker and tired…eventually when you succeed and the virus starts being destroyed (this might take a few days) you start getting energetic and cheerful again!
Cassandra Raby answered on 13 Nov 2013:
Oh the flu… we try so hard to not let us catch it… but somehow that pesky virus gets in.
Someone just sneezed next to you? Yuck! That’s just put all the viruses into the air to float about to the next person. All that snotty mucus in your nose? That tries to capture the virus when it flies into your nose when you’re breathing. And you have mucus in your throat to try and stop it too! Even your saliva has cells in it ready to fight any disease that tries to get in.
But sometimes, your immunity doesn’t manage to stop it. A sneaky little virus gets in. The flu viruses are quite clever… they change their clothing very often, like a disguise.. so your body isn’t naturally protected against them as they can’t tell what disease it is (it’s a good disguise)!
So once it has entered the virus makes it to your lungs and enters cells to multiple in.
Flu is a pretty dangerous disease.. but we have got much better at knowing how to manage it. We can predict what kind of disguise it will be wearing and then use that to make the vaccines.
Thomas Doherty-Bone answered on 13 Nov 2013:
Looks like my contemporaries have covered everything.
So to summarise: Infected person (the host)-virus escapes through sneezing, touching, licking random stangers I see in town-lots of people hiding from cold indoors close to each other-virus enters one person-person’s immune system destroys virus-similar virus with signature that doesn’t say “I’m a virus” to host’s immune system enters-virus infects host-multiplies in host’s airways-host sick :-(=flu. Repeat.
I had flu twice in two months recently. A result of lots and lots of hosts coming to the university for the start of the academic year here at Leeds. Bloody students!