In fact flu will contagious, one to four days for symptoms to develop. However, if you want to make sure that it is the common cold or flu to watch, you should be checked by a doctor. Serious flu symptoms ,such as swine flu or bird flu, is quite similar to ordinary flu due to climate change. So when you start to cough or sore throat ahead of the flu, then you've actively transmit the virus to people around you.
Flu is easily spread through the air and can contagious anyone who has a weakened immune system. But really how long are you contagious with the flu? To determine how long flu can survive outside, it varies depending on where the droplets of liquid or air containing the virus falls.
Sprays of water vapor when you sneeze or cough can reach up to one meter. People around you can be infected by touching droplets on a sofa, table, or the door knob and then "delivered" unknowingly by touching your mouth or nose.
The important thing to note is that flu virus contagious, especially when someone who is not infected had direct contact such as a handshake with an infected person. While other infections occurs indirectly. One of the best ways to avoid the flu or a cold is frequent hand washing with soap and water or alcohol-based hand sanitizer. Also try to stop the bad habit of rubbing his eyes or biting your nails.