Skip to content

Cold, Flu, & Cough Health Center

Select An Article

What Causes the Flu?

Font Size

In order to prevent getting the flu, it is important to understand what causes the flu

 

Recommended Related to Cold & Flu

The Truth About 'Man Colds'

When Gina Gallo, a school librarian in Lacombe, La., gets sick, she can take care of herself. She gets her own medicine, makes her own food, and "deals with it," as she puts it. But when her fiancé gets a cold, she says he has "a complete system breakdown." "The world stops and the whining is incessant," she says. "I am expected to bring him food, take care of him, and generally treat him like the baby that he is." Gallo's fiancé declined to talk with WebMD for this story. Their Mars-Venus situation...

Read the The Truth About 'Man Colds' article > >

What Types of Viruses Cause the Flu?

The flu is actually very different from a cold. While more than 100 different viruses can cause a cold, only influenza virus types A, B, and C cause the flu.

Type A and B viruses are responsible for the large flu epidemics. Type C flu virus is more stable and usually causes milder respiratory symptoms. While the flu vaccine can help protect you from type A and B flu viruses, there is no immunization or flu shot for type C virus.

Type A flu virus is divided into different subtypes based on the chemical structure of the virus. Type B flu virus is not divided into subtypes. Both type A and type B flu viruses are responsible for the seasonal outbreaks of flu.

Type A flu viruses are found in many different animals, including ducks, chickens, pigs, whales, horses, and seals. Influenza B viruses circulate widely only among humans.

How Is the Flu Virus Spread?

The flu is a highly contagious disease. The flu virus is spread when you either inhale infected droplets in the air (spread when an infected person coughs or sneezes) or when you come in direct contact with an infected person's secretions (by kissing, touching, and sharing objects such as silverware). You can also transfer the flu virus to your hands by touching smooth surfaces such as doorknobs, handles, television remotes, computer keyboards, and telephones. Then when you touch your hands to your nose, eyes, or mouth, the flu virus gets absorbed.

What Is a Flu Epidemic?

Flu outbreaks are classified as epidemics, which means they occur in a set geographical area, or pandemics, which means a worldwide occurrence. According to the CDC, winter flu epidemics can cause illness in 10% to 20% of the population and are associated with 3,000 to 49,000 deaths and more than 200,000 hospitalizations per year in the United States.

Why Do People Usually Get the Flu in Winter?

Flu outbreaks occur more frequently in the winter months. Many factors may play a role in the flu's seasonal pattern including. Here's why:

  • The flu virus survives for longer periods indoors in winter because the relative humidity of indoor air is very low in comparison to the outside air.
  • The flu virus may stay suspended in the air for prolonged periods and thus infect others by being inhaled. The flu virus droplets can also infect by landing on sensitive body areas such as the eyes, nose, or mouth.
  • In winter, humans tend to be indoors more and thus have closer contact with each other, which makes it easier for the flu virus to spread.
Next Article:

Today on WebMD

hot toddy
15 tips to help you feel better.
man sneezing into elbow
Do echinacea and vitamin C really help a cold?
 
teen girl coughing
Get a good night’s rest with these remedies.
elder berry
Eat these to fight colds, flu, and more.
 
Natural Cold Flu Remedies Slideshow
Slideshow
cold weather
VIDEO
 
Allergy And Sinus Symptom Evaluator
Article
Boy holding ear
Slideshow
 

Loaded with tips to help you avoid food allergy triggers.

Loading ...

Sending your email...

This feature is temporarily unavailable. Please try again later.

Thanks!

Now check your email account on your mobile phone to download your new app.

woman receiving vaccine shot
Article
woman with fever
Article
 
Waking up from sleep
Article
woman with sore throat
Slideshow