What is the common cold, and what causes it?
The common cold is a self-limited contagious illness that can be caused by a number of different types of viruses. The common cold is medically referred to as a viral upper respiratory tract infection. Symptoms of the common cold may include cough, sore throat, nasal congestion, runny nose, and sneezing. More than 200 different types of viruses are known to cause the common cold, with rhinovirus causing approximately 30%-35% of all adult colds. Other commonly implicated viruses include coronavirus,adenovirus, respiratory syncytial virus, and parainfluenza virus. Because so many different viruses can cause a cold and because new cold viruses constantly develop, the body never builds up resistance against all of them. For this reason, colds are a frequent and recurring problem. In fact, children in preschool and elementary school can have six to 12 colds per year while adolescents and adults typically have two to four colds per year. The common cold occurs most frequently during the fall and winter months.
The common cold is the most frequently occurring illness in the world, and it is a leading cause of doctor visits and missed days from school and work. It is estimated that individuals in the United States suffer 1 billion colds per year, with approximately 22 million days of school absences recorded annually.
How is the common cold transmitted?
The common cold is spread either by direct contact with infected secretions from contaminated surfaces or by inhaling the airborne virus after individuals sneeze or cough. Person-to-person transmission often occurs when an individual who has a cold blows or touches their nose and then touches someone or something else. A healthy individual who then makes direct contact with these secretions can subsequently become infected, often after their contaminated hands make contact with their own eyes or nose. A cold virus can live on objects such as pens, books, telephones, computer keyboards, and coffee cups for several hours and can thus be acquired from contact with these objects.
The symptoms of the common cold typically begin two to three days after acquiring the infection (incubation period). Symptoms and signs of the common cold vary depending on the virus responsible for the infection and may include the following
- • nasal stuffiness or drainage, • sore or scratchy throat, • sneezing, •hoarseness, • cough, • watery eyes, • low-grade fever, • headache, • body aches, and • fatigue.
The signs and symptoms of the common cold in infants and children are similar to those seen in adults. The cold may begin with a runny nose with clear nasal discharge, which later may become yellowish or greenish in color. Infants and children may also become more fussy and havedecreased appetite.
The symptoms of the common cold will typically last anywhere from four to 14 days, with most individuals improving in one week.
Does it have anything to do with exposure to cold weather?
Though the common cold usually occurs in the fall and winter months, the cold weather itself does not cause the common cold. Rather, it is thought that during cold-weather months people spend more time indoors in close proximity to each other, thus facilitating the spread of the virus. For this same reason, children in day care and school are particularly prone to acquiring the common cold.