What is influenza (flu)?
Influenza (flu) is an easily spread
respiratory tract infection. It is caused by a virus. About 1 in 20 to 1 in 5 of people
in the U.S. get the flu each year. The flu usually starts abruptly, with fever, muscle
aches, sore throat, and a cough.
The flu can make people of any age
sick. Most people are sick with the flu for only a few days. But some have a much more
serious illness. They may need to go to the hospital. The flu can also lead to pneumonia
The flu viruses continually change.
Currently, 3 different influenza viruses circulate worldwide. Vaccines are given each
year to protect against the flu virus strains expected to cause the illness that
What causes the flu?
The flu is caused by a virus. Viruses are generally passed from person to person through the air when an infected person sneezes or coughs.
But the virus can also live for a short time on objects like doorknobs, pens, pencils, keyboards, phones, and cups or eating utensils. So you can also get the flu by touching something that has been recently handled by someone infected with the virus and then touching your own mouth, nose, or eyes.
What are the symptoms of the flu?
Each person may have different
symptoms. The flu is called a respiratory disease. But it can affect your whole body.
People usually become very sick with several, or all, of these symptoms:
- Cough, often becoming severe
- Extreme exhaustion
- Fatigue for several weeks
- High fever
- Runny or stuffy nose
- Severe aches and pains
- Sneezing at times
- Sometimes a sore throat
- Vomiting and diarrhea
Fever and body aches often last for
3 to 5 days. But cough and fatigue may last for 2 weeks or more.
The symptoms of the flu may look
like other health problems. Always talk with your healthcare provider for a
How is the flu diagnosed?
The flu is diagnosed based on your
symptoms. Lab tests may be used to confirm the diagnosis, if needed.