A viral infection characterized by inflammation of the mucous membranes lining the upper respiratory passages and usually accompanied by malaise, fever, chills, coughing, and sneezing. In this sense, also called common cold, coryza. The common cold is a general inflammation of the mucus membranes of the respiratory passages caused by a variety of viruses.
Colds are highly contagious.
The difficulty modem medicine has had in finding a cure for the common cold may lie in the fact that there are so many different types of viruses that cause colds. In addition, each new generation of viruses changes slightly in its chemical makeup, and it appears that new viruses are becoming stronger and stronger every year. At the start of a cold, the body's immune system produces a chemical called an antibody which attacks the virus, preventing harm to healthly cells. For the body to effectively fight a virus, an antibody that exactly matches the virus must be produced. There are a number of immune processes that take place after infection which allow the virus to be recognised and appropriate antibodies produced.