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What is the common cold?

The common cold is an infection of the upper respiratory tract - the nose, nasal passages and the throat. There are more than 200 viruses that can cause colds. The primary family of viruses that cause common colds in adults are the rhinoviruses. There are more than one hundred kinds of rhinoviruses. These are also called "nose viruses", based on a Greek word "rhino" meaning nose.


What are the symptoms of common cold?

Symptoms usually show up about two days after a person becomes infected. Early signs of a cold are a sore, scratchy throat, sneezing, and a runny nose. Other symptoms that may occur later include headache, stuffy nose, watering eyes, hacking cough, chills, muscle aches, and general malaise (ill-feeling) lasting from 2 to 7 days. Some cases may last for two weeks. The common cold may be accompanied by:

  • laryngitis (inflammation of the larynx or "voice box");
  • tracheitis (inflammation of the membrane lining the trachea or "wind pipe");
  • bronchitis (inflammation of the bronchial membranes);
  • ear infection or
  • worsening of asthma.

(Our OSH Answers How Do Particulates Enter the Respiratory System? explains more about parts of the respiratory tract.)

These inflammations may make one more susceptible to more serious complications such as

  • sinusitis (inflammation of sinus membranes) and
  • pneumonitis (inflammation of the lungs).

Although no fatalities have been reported among otherwise healthy workers the disability is important because it affects work performance and absenteeism.


Can someone be infected with a cold virus and not show symptoms?

Yes, it is even possible to be exposed to cold viruses and not become infected. When people are infected, they can be asymptomatic (i.e., showing no symptoms); this is called a sub-clinical infection since the infection is not causing a disease. Most people with colds show mild symptoms but severe colds can send one to bed with all the nasty symptoms of headache, fever, aches and pains all over, stuffy nose and coughing.


How widespread is the common cold?

Common cold infections are so widespread that there can be very few people who escape the infection each year. It has been estimated that adults suffer 2 to 5 colds per year and is one of the leading causes of missed days at work.


How are common cold viruses transmitted?

Colds are really not very contagious, compared to other infectious diseases. Close personal and prolonged contact is necessary for the cold viruses to spread. The viruses must get into the nose where they can infect the nasal membranes. The virus must attach to nasal cells after which the viruses can multiply. Inhaling contaminated droplets produced when someone else coughs or sneezes may be one way to catch a cold.

Cold viruses can remain infective even if they are outside the body for a few hours. You can catch a cold if you handle something that is contaminated with a cold virus and then stick your contaminated finger up your nose or rub your eyes. The cold viruses can reach the nose when you rub your eyes because the virus can be passed down the tear ducts that go from the eyes into the nasal cavities.


Do chills or exposure to cold temperatures cause colds?

In a word - no. Some people may sneeze if their skin is cooled. More people catch colds when the weather temperature is cold than when it is warm outside because they tend to be inside more often and longer. People tend to blame cool temperatures for getting a cold rather than being in closer, prolonged contact with people who have a cold.

Some people associate exposure to the cool air from air conditioners as a cause of colds. Again, it is not the temperature that is the culprit.

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Document last updated on August 5, 2008

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