What is the seasonal flu?

Influenza, or the flu, is a contagious respiratory illness caused by influenza viruses. There are two main types of influenza virus: Types A and B. Influenza A and B viruses that routinely spread in people are responsible for seasonal flu epidemics each year.

Seasonal flu can cause mild to severe illness. Sometimes flu complications can be fatal, particularly among people who have an underlying health condition. The H1N1 or swine flu is a new strain of Type A influenza that was discovered in April 2009. Unlike strains of the seasonal flu that have circulated in past years, fewer people have immunity to the H1N1 strain.

Symptoms

Symptoms of the seasonal flu include one or more of these conditions:

Symptoms of the seasonal flu and the H1N1 flu are very similar.

Although the flu and the common cold are both respiratory illnesses that can have similar symptoms, they are caused by different viruses. In general, the flu is worse than the common cold, and symptoms such as fever, body aches, extreme tiredness, and dry cough are more common and intense. Colds are usually milder than the flu. People with colds are more likely to have a runny or stuffy nose. Colds generally do not result in serious health problems, such as pneumonia, bacterial infections or hospitalizations.

How does it spread?

Flu viruses are thought to spread mainly from person to person through coughing or sneezing of people with influenza. When people with the flu cough or sneeze, they release the virus into the air and onto surfaces. When other people breathe in the particles or touch something with the flu virus on it and then touch their eyes, nose or mouth, they introduce the virus into their bodies.

Sometimes people may become infected by touching something with flu viruses on it and then touching their mouth or nose.

People may be able to infect others beginning one day before symptoms develop and up to five to seven days after becoming sick. That means that you may be able to pass on the flu to someone else before you know you are sick, as well as while you are sick.

Protecting yourself

Protecting others

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Last updated Sep 27, 2011