Influenza, commonly referred to as the flu, is an infectious disease caused by RNA viruses of the family Orthomyxoviridae (the influenza viruses).
Influenza, or flu, is a respiratory illness that is caused by a virus. Flu is highly contagious and is usually spread by the coughs and sneezes of a person who is infected.
You can also catch flu from an infected person if you touch them (e.g. shaking hands). Adults are contagious one day before getting symptoms and up to 7 days after becoming ill. This means that you can spread the influenza virus before you even know you are infected. A flu epidemic, when a large number of people in one country are infected with flu, can last several weeks.
According to the National Institutes of Health, between 5% and 20% of Americans get the flu each year. More than 200,000 people are hospitalized and 36,000 die annually because of flu in the United States.
What are the symptoms of flu?
It is common to confuse flu with a bad cold. Flu and cold symptoms may include a runny/blocked nose, sore throat, and cough. Here are some symptoms which a person with flu will have. These are not common heavy cold symptoms:
- high temperature
- cold sweats, shivers
- headache
- aching joints, aching limbs
- fatigue, feeling utterly exhausted
- gastro-intestinal symptoms, such as nausea, vomiting, and diarrhea, are much more common among children than adults
These symptoms may linger for about a week. The feeling of tiredness and gloom can continue for several weeks.
How serious is flu?
In the majority of cases flu is not serious - it is just unpleasant. For some people, however, there can be severe complications. This is more likely if you are elderly or have some other longstanding illness that can undermine your immune system. Your risk of experiencing severe flu complications is higher if:
- you are over 65
- you are a baby or a very young child
- you are pregnant
- you have some kind of heart or cardiovascular disease
- you have a chest problem, such as asthma or bronchitis
- you have a kidney disease
- you suffer from diabetes
- you are taking steroids
- you are undergoing treatment for cancer
- you have any longstanding disease that can significantly lower your immune system
