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Meet the influenza virus
Influenza is caused by a virus—a tiny particle that consists of RNA (genetic material also known as ribonucleic acid) inside a protein coat.
The influenza virus, like other viruses, can only reproduce by taking over a "host" cell (a cell that provides nourishment for the virus).
Here is how influenza can spread:
- A person who is infected with influenza coughs or sneezes, releasing tiny particles of virus. (This person may not even feel sick at the time.)
- Another person in the room may breathe in the viral particles.
- The viral particles can then attach themselves to cells in the nose, throat, and lungs of this second person.
- Each cell that has been infected by influenza becomes a little "influenza factory," making more virus to infect additional cells.
- The damage to the cells in the nose, throat, and lungs can cause the person to cough, thereby helping to spread the influenza virus to other people.
- Viral particles that land on doorknobs, telephones, and other surfaces can cause infection if someone picks up influenza on their hands and then touches their nose, mouth, or eyes.
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Many of the symptoms of influenza—fever, chills, and body aches — are really signs that your immune system is working very hard to fight infection. They are caused by cytokines, chemicals produced by activated immune cells.
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For U.S. Residents Only
