The Common Cold
Sneezing, scratchy throat, runny nose-everyone knows the first signs of a cold, probably the most common illness known. Although the common cold is usually mild, with symptoms lasting 1 to 2 weeks, it is a leading cause of doctor visits and missed days from school and work. According to the Centers for Disease Control and Prevention, 22 million school days are lost annually in the United States due to the common cold.
In the course of a year, people in the United States suffer 1 billion colds, according to some estimates.
Children have about 6 to 10 colds a year. One important reason why colds are so common in children is because they are often in close contact with each other in daycare centers and schools. In families with children in school, the number of colds per child can be as high as 12 a year. Adults average about 2 to 4 colds a year, although the range varies widely. Women, especially those aged 20 to 30 years, have more colds than men, possibly because of their closer contact with children. On average, people older than 60 have fewer than one cold a year.
More than 200 different viruses are known to cause the symptoms of the common cold. Some, such as the rhinoviruses, seldom produce serious illnesses. Others, such as parainfluenza and respiratory syncytial virus, produce mild infections in adults but can precipitate severe lower respiratory infections in young children.