Influenza, that dreaded viral infection, is perhaps best known as a seasonal illness, particularly common in the winter. Most people will have experienced it at some point in their lives, for some people on multiple occasions, and it is always a most miserable time, even if they do get some time off work as a result.
Symptoms of the disease include chills, coughs, fever, headaches, muscle pain and pharyngitis. In extreme cases influenza can cause serious tissue damage such as haemorrhage or oedema, or allow secondary infections to appear such as pneumonia, and these can be fatal. This is especially true for the most vulnerable people such as children and the elderly and those with weakened immune systems.
Influenza is a much more serious disease than the ordinary common cold and the two should not be confused. Typically people can continue to function pretty well with a cold but contracting influenza can put you out of action for days. The common cold is caused by a type of virus called the rhinovirus and this is a different type of virus from that which causes influenza.
In the case of influenza there are five distinct types of virus at work. These are called Influenzavirus A, Influenzavirus B, Influenzavirus C, Isavirus, and Thogotovirus, and are RNA viruses from the family of viruses called Orthomixoviridaes. The Spanish Flu pandemic of 1918, which killed anything from 40 million to 100 million people worldwide, was an Influenzavirus A type virus called H1N1, for example.
But the virulence and ease of treatment can vary across the different types and across different strains of the same virus from year to year. The development and production of treatments and vaccines is a slow and costly process so in the cases of strains of the virus that are quick to mutate it can be very difficult to keep them up to date.
The main route of transmission of the influenza virus is through the air via coughing and sneezing. But many other bodily secretions such as blood and saliva can also transmit the virus from person to person. The virus can even be caught from contact with infected surfaces rather than immediate contact with another person.
The virus can be killed by detergents and disinfectants. This means that cleaning surfaces thoroughly and washing your hands can decrease the chances of transmission. But obviously if you have a hectic life, interacting with people on buses, trains, shops, or in the workplace, it is not really possible to completely rule out catching it through their coughs and sneezes.