How does the flu infect the body?

Scientists believe that flu viruses are spread when people with the flu cough, sneeze, or talk, expelling tiny droplets containing the virus. These droplets can land on other people’s noses or mouths, or can be inhaled. People who are as far as 6 feet away can become infected. The droplets can also land on surfaces, such as tabletops or telephones. If a healthy person touches the object that has droplets containing the virus on it, and then touches his mouth or nose, he can become infected.
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When the flu virus enters the body, it moves into the respiratory tract. There, the virus binds to the surface of cells and releases its genetic information (RNA) into the cell's nucleus, where the cell's genetic information (DNA and RNA) is stored. As the virus replicates, or copies itself, it takes over the functions of the cell. The virsus' copies move to the cell membrane. When the cell finally dies, it releases the copies into the body, where they infect other cells.

As the virus moves into the bloodstream, the first symptoms begin. The replication process continues for several days, until the body's immune system starts to fight off the virus.

Flu symptoms can include the following:

  • Sneezing
  • Coughing
  • Fever
  • Runny nose
  • Tiredness
  • Body aches and congestion

Although uncomfortable, these symptoms are generally not dangerous. The flu also weakens the immune system, however, leaving it vulnerable to more serious infections. Individuals in high-risk health categories are most susceptible to serious complications, such as:

  • Dehydration
  • Sinus problems and ear infections (primarily in children)
  • Bacterial pneumonia
  • Worsening of preexisting conditions, such as asthma or diabetes

Continue Learning about Cold and Flu

Cold and Flu

Cold and Flu

Colds and flu are both viral infections, but have different symptoms. With a cold you will have symptoms such as a runny nose or a sore throat. Flu symptoms come on suddenly and may include fever, body aches or vomiting. While the...

re is no cure for either, there are treatments -- chicken soup, nasal sprays, rest -- which can help your feel better.

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.