What is flu?

About 6 months ago it was the turn of Australia to fall victim; now the northern hemisphere is in the grip of flu! But what is this agent, and how does it make us unwell? Georgia Mills has the “flu’s flu” of flu...

Georgia - Despite causing such a big problems, the influenza virus is tiny - a spiky football about one 10000’th the size of a full stop, comprising a package of genetic material protected by an outer coat. And once it’s inside you, this little package packs a punch.

And how do you get it in the first place? Flu in transferred from person to person through tiny droplets of liquid that you breathe in. A sneeze from an infected person can contain hundreds of thousands of virus particles. Or viruses can survive on surfaces like phones and handrails for two days waiting to literally be picked up. So if you come into contact with flu and don’t wash your hands, there’s a high chance it will make its way inside you and begin its dirty work.

Like all viruses, it can’t reproduce on its own – it needs the cells in your body for that. When flu lands on a cell it is taken inside and then aggressively hijacks the machinery inside and, before you know it...

The virus begins to multiply, ultimately making thousands of new flu particles. These bud off and infect neighbouring cells, first also converting them into flu factories, and then eventually killing them. But these infected cells sound the alarm with a chemical signal that causes other nearby cells to go into lockdown, making it harder for the flu to get in. But these signals also lead to some of the flu’s nastier symptoms, like fevers, aches and pains, and fatigue.

Some of the other symptoms like a running nose and blocked sinuses are also caused by your own body as it goes into defensive mode – mucus makes it much harder for the virus to spread to other cells, and other infectious agents trying to access your airways are thwarted.

And as well as going on the defensive, your body also prepares a counter-attack. Your immune system learns what the invader looks like and goes on the offensive, producing legions of antibodies and white blood cells to fight off the assault. But, unfortunately, unless you’ve had the same strand of flu before, it takes time for your immune system to take action, which is why you can be bedridden for days.

And for those of us who are over 65, pregnant or with a compromised immune system, the flu can pose a serious threat, leaving you vulnerable to other infections, like pneumonia.

So when it’s flu season, it’s best to sneeze into tissues and wash your hands regularly, and if you think you have flu, don’t go to work, as you’re most likely to pass it on in the early stages of the disease.