Minor disease of the upper respiratory tract,
caused by a variety of viruses. Symptoms are
headache, chill, nasal discharge, sore
throat, and occasionally cough. Research
indicates that the virulence of a cold
depends on psychological factors and either a
reduction or an increase of social or work
activity, as a result of stress, in the
previous six months. There is little
immediate hope of an effective cure since the
viruses transform themselves so rapidly.