Influenza virus

What is Influenza (also called Flu)?

The flu is a contagious respiratory illness caused by influenza viruses that infect the nose, throat, and lungs. It can cause mild to severe illness, and at times can lead to death. The best way to prevent the flu is by getting a flu vaccine each year.

Signs and Symptoms

People who have the flu often feel some or all of these signs and symptoms:

Fever* or feeling feverish/chills
Cough
Sore throat
Runny or stuffy nose
Muscle or body aches
Headaches
Fatigue (very tired)
Some people may have vomiting and diarrhea, though this is more
common in children than adults.

*It’s important to note that not everyone with flu will have a fever.

How Flu Spreads

Most experts believe that flu viruses spread mainly by droplets made when people with flu cough, sneeze or talk. These droplets can end up in the mouths or noses of people who are nearby. Less often, a person might also get flu by touching a surface or object that has flu virus on it and then touching their own mouth, eyes or possibly their nose.

Period of Contagiousness

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. Most healthy adults may be able to infect others beginning 1 day before symptoms develop and up to 5 to 7 days after becoming sick. Some people, especially young children and people with weakened immune systems, might be able to infect others for an even longer period. The time from when a person is exposed to flu virus to when symptoms begin is about 1 to 4 days, with an average of about 2 days.

Complications of Flu

Complications of flu can include bacterial pneumonia, ear infections, sinus infections, dehydration, and worsening of chronic medical conditions, such as congestive heart failure, asthma, or diabetes.

People at High Risk from Flu

Anyone can get the flu (even healthy people), and serious problems related to the flu can happen at any age, but some people are at high risk of developing serious flu-related complications if they get sick. This includes people 65 years and older, people of any age with certain chronic medical conditions (such as asthma, diabetes, or heart disease), pregnant women, and young children.

Preventing Flu

The first and most important step in preventing flu is to get a flu vaccination each year. The CDC also recommends everyday preventative actions (like staying away from people who are sick, covering your mouth when you cough and sneeze and frequent handwashing) to help slow the spread of germs that cause respiratory illnesses (i.e. of the nose, throat, and lungs), like flu.

Treatment

There are influenza antiviral drugs that can be used to treat flu illness.

Oseltamivir, zanamivir and peramivir

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