Introduction
Upper respiratory tract infections affect the airways in the nose, ears, and throat.
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| Structures of the throat include the esophagus, trachea, epiglottis and tonsils. |
The infections can be caused by viruses, bacteria, or other microscopic organisms. In most cases, these infections lead to colds or mild influenza (flu) and are temporary and harmless. In rare cases, flu can be severe, or the infections may turn into pneumonia.
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Organisms that cause these upper respiratory tract infections are generally spread by:
- Direct contact (such as hand-to-mouth)
- Coughing or sneezing
The Common Cold
The common cold (medically known as infectious nasopharyngitis) is the most common upper respiratory tract infection. More than 200 viruses can cause colds. The most common cause is the rhinovirus, which is responsible for about half of all colds. Symptoms usually develop one to three days after being exposed to the virus.
A cold usually progresses in the following manner:
- It nearly always starts rapidly with throat irritation and stuffiness in the nose.
- Within hours, full-blown cold symptoms usually develop, which can include sneezing, mild sore throat, fever, minor headaches, muscle aches, and coughing.
- Fever is low-grade or absent. In small children, however, fever may be as high as 103 degrees F for one or two days; it should go down after that and be normal by the fifth day.
- Nasal discharge is usually clear and runny the first one to three days. It then thickens and becomes yellow to greenish.
- The sore throat is usually mild and lasts only about a day. A runny nose usually lasts two to seven days, although coughing and nasal discharge can persist for more than two weeks.
Influenza (The "Flu")
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