Flu (Influenza) and Pandemic Flu

What is flu (influenza)?
Flu, or influenza, is a contagious illness caused by a flu virus. It attacks the nose, throat and lungs in people. Anyone, including healthy people, can get the flu. Serious health problems from the flu can happen at any age.

What are the types of flu viruses?
There are three types of flu viruses: A, B, and C. Influenza type A viruses can infect people, birds, pigs, horses, seals, whales and other animals. Wild birds are the natural hosts for these viruses. Influenza B viruses are usually found only in humans. Influenza type C viruses cause mild illness in people.

How are seasonal flu, avian influenza (bird flu) and pandemic flu different?

  • Seasonal flu follows predictable yearly patterns, in Texas generally from October through March. Viruses associated with seasonal flu include influenza A, influenza B and influenza C. People usually have some immunity built up from previous exposure to circulating seasonal flu viruses.
  • Avian influenza (bird flu) is an infection caused by bird flu viruses. These bird flu viruses occur naturally among birds worldwide. Rarely, transmission is possible from sick or dead birds to people.
  • A pandemic is a global disease outbreak. A flu pandemic is possible when an influenza A virus makes a dramatic change that results in a new or novel virus to which people have little or no immunity. The new virus then begins to cause serious illness, spreads easily from person to person and can sweep around the world quickly.

How do you get the flu?
Flu is very contagious. It can be caught from breathing in droplets in the air from someone sneezing, coughing or talking. The flu also is spread when people touch something with the flu viruses on it such as a doorknob or handrail, and then touch their eyes, nose or mouth. People can spread flu from one day before symptoms appear to seven days after symptoms go away.

What are the symptoms of flu?
Symptoms of flu come on suddenly, one to four days after the virus enters the body. These symptoms include:

  • Sudden fever (100.4º F or more)
  • Headache
  • Tiredness, sometimes extreme
  • Dry cough
  • Sore throat
  • Nasal congestion
  • Body aches

Children also may have an ear infection, nausea or vomiting. Young children with flu can develop high fevers and seizures. Generally, people start feeling better after the body's temperature returns to normal, in about three days, and are ready to return to their normal activities in about a week. Tiredness and a cough may linger for several more weeks.

What are some complications from the flu?
In people with chronic medical conditions such as heart or lung disease, kidney disease or diabetes, flu can lead to pneumonia and other life-threatening illnesses. Others at higher risk of complications include those with weakened immune systems, the elderly, the very young and pregnant women.

How is flu treated?
Four antiviral medicines – amantadine (Symmetrel®), rimantadine (Flumadine®), oseltamivir (Tamiflu®) and zanamivir (Relenza®) – are approved by the U.S. Food and Drug Administration for treating flu. All four usually work against influenza A viruses. However, the drugs may not always work because flu virus strains can become resistant to one or more of these medicines. To be effective, antivirals should be taken within 48 hours of the beginning of symptoms. Antivirals do not cure the flu.

How is flu prevented?
Vaccination is the best way to prevent flu and its severe complications. It takes about two weeks after vaccination for a person to be fully protected. A live, weakened vaccine givenas a nasal spray also is available for people 5 to 49 who are in good health and are not pregnant. A vaccine will need to be developed to match a new or novel virus strain that is transmitted person to person. Other prevention suggestions include:

  • Wash your hands often, especially after being in contact with someone who has a respiratory infection or with children who get viruses easily.
  • Avoid touching your eyes, nose or mouth.
  • Use a tissue when you cough or sneeze, then throw the tissue away.
  • Avoid close contact with those who are sick.
  • Stay home if you are sick. Keep children at home if they are sick.
  • Wipe surfaces such as bathroom and kitchen sinks, faucets and counters with a mixture of 1 part household bleach to 9 parts water.
  • Take good care of yourself physically and emotionally.

What is the difference between the flu and a cold?
The flu and the common cold are both respiratory illnesses, but they are caused by different viruses. Unlike flu, the common cold comes on gradually, rarely causes fever and is usually limited to a sore throat, coughing, sneezing and a stuffy, runny nose. In general, the flu is worse than the common cold. Symptoms such as fever, body aches, extreme tiredness and dry cough are more common and intense and come on more suddenly. Colds generally do not result in serious health problems such as pneumonia, bacterial infections or hospitalizations.


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Last updated May 20, 2015