Introduction
Influenza is a contagious respiratory illness that is caused by different types of influenza virus. The flu is spread by coughs and sneezes, and can cause mild to severe illness, depending on which type of virus is responsible for the infection, and the health status of the infected individual. The best way to prevent the flu is by getting a vaccination each year, but antiviral medications can also be effective for people who are unable to get vaccinated.
Each year, about 10% to 15% of the population gets influenza, and up to 36,000 people die from the illness. Sometimes the flu is mistaken for a bad cold. The best way to tell if someone if suffering from influenza, rather than a cold, is by looking at their symptoms. The main differences between the flu and a bad cold are:-
- The flu causes a dry feeling in the nose and throat, while colds cause a runny nose.
- Muscular pains and shivering occur with the flu but not with a cold.
- Flu symptoms can last for up to a week, while cold symptoms last for only one or two days.
- The flu can cause very high fever, while colds only sometimes cause a mild fever.
Influenza outbreaks (epidemics) arise when there are minor changes in the nature of the virus. When this happens, it is more difficult for our bodies to recognise the virus, which means that more people become sick. Worldwide epidemics are called pandemics, and occur when there are major changes in the virus, and often cause many deaths.
There are three type of influenza virus:-
Influenza A virus causes illness in birds and mammals. It is rare in humans but can be very severe. This type of virus is often responsible for flu epidemics and also pandemics.
Influenza B virus commonly affects humans. This virus is less severe than type A and causes epidemics, but not pandemics.
Influenza C virus causes mild illness in humans and also pigs. It is not associated with influenza epidemics or pandemics.