The Common Cold

What we refer to as “The Common Cold” is actually caused by several different viruses. Most are caused by Rhinovirus.. They usually present as an acute self-limiting infection, which means it comes on quickly and resolves by itself. The upper respiratory tract (nose, throat, and larynx) is usually the most affected by Rhinovirus. The incubation period after picking up the virus is usually about two days before our symptoms start. The illness can then last for 5-7 days. You are likely to be contagious while you have symptoms, but you’re most contagious in the early part of illness (the first few days). As your immune system begins to fight the virus, the concentration of virus in your body will drop off and you will recover. Humans develop immunity to virus by sending white blood cells to kill the virus and making antibodies active against it. 

It is a commonly held belief that rhinovirus symptoms are different than those associated with influenza (the flu). However, all the viruses discussed can cause an influenza-like illness. Most people infected with influenza virus have only mild symptoms or are asymptomatic. Many infected with influenza have exactly the same symptoms as those infected with rhinovirus.

For this reason it is usually not possible for you, or a doctor, to tell whether you are suffering from a cold or flu. Hence, the term “ILI” or “influenza-like illness” is also used for colds, especially where there is also fever.

While influenza might sometimes be associated with more severe respiratory infections, rhinovirus gives it a good run for its money. During most winters, rhinoviruses cause more cases of pneumonia requiring hospitalization than do influenza viruses.  


From: 
http://theconversation.com/health-check-what-is-the-common-cold-and-how-do-we-get-it-60857