Well over 100 types of cold viruses are known. There is no evidence that cooling the body induces a cold. Infection may be facilitated by excessive fatigue, emotional stress and other factors that weaken the body's immune defenses. Bacteria that live in the nose and throat can gain a foothold and cause secondary infection such as ear infections, bacterial sinusitis and bacterial bronchitis. Symptoms and Signs.
Colds usually begin abruptly.
Throat discomfort is often first, followed by sneezing, runny nose, nasal congestion and decreased energy level. Fever is unusual, but children and infants may have fever up to 102 degrees. Mucous becomes thick. Coughing, if present, can last two to three weeks. Green or yellow sputum or nasal secretions suggest a secondary bacterial bronchitis or sinusitis.