Influenza, usually just called flu, is a very contagious illness caused by influenza viruses which originated in birds (avian influenza). The deadly Spanish flu pandemic of 1918 killed an estimated 50 million and is believed to have been caused by a bird flu virus that jumped to humans. There are many types of the viruses and flu symptoms vary with each one from mild to severe.
When you catch a flu, within about two days your nose, throat and sometimes the lungs will be affected – you’ll most likely experience a sore throat, runny or blocked nose, headache, muscle ache, cough, fatigue and usually also fever.
Most people recover within a week but flu can cause severe illness or even death in people whose health is already compromised, have an underlying infection or are vulnerable, such as very young children or the elderly.
Flu viruses spread by tiny droplets that ill people expel when coughing, sneezing or speaking. You can get infected by breathing in the droplets or if these land directly in your mouth or nose. Another way of infection is when an infected person touches a surface with a contaminated hand and you then touch it too and bring your hand to your own mouth, nose or eyes – effectively delivering the virus into your body. That’s why to prevent transmission, you should cover your mouth and nose with a tissue when coughing and wash your hands regularly.
You may spread the virus before you know you are ill because you are already infectious one day before you notice any symptoms. People with flu are the most contagious during the first three days of their illness. You can then infect others for up to seven days after falling ill. Treatment is meant to relieve symptoms and facilitate recovery but there is no specific cure for flu. If you become ill, you should rest, drink plenty of liquids, eat a nutritious vegan diet and use medicines that offer relief from pain, inflammation and reduce fever if needed. As flu is a viral disease, there’s no point treating it with antibiotics – those only work on bacterial infections.