Flu

Influenza, commonly known as the flu, is a seasonal contagious respiratory illness that can be caused by three different types of viruses, which differ from each other depending on the proteins present on their surface. 

It can be easily transmitted directly, by way of droplets of saliva or mucus, by coughing or sneezing, as well as by simply talking to an infected person, or indirectly, through contact with hands contaminated with the influenza virus. 

Influenza outbreaks occur mostly in winter, peaking between December and March. Sporadically, infections can also occur at other times of the year, although very rarely in summer. 

The seasonal flu can significantly impact public health, being the infectious disease with the highest incidence and mortality rate, generating high costs as a result of emergency room admissions and hospitalisations. Infections also result in significant direct and indirect costs, due to the need to manage a high number of cases, with possible complications, and the fact that each one of us can experience the disease several times in their lifetime, regardless of lifestyle, age or geographical area. 

Influenza usually has a short incubation period, ranging from 1 to 3 days, and is characterised by a sudden onset of symptoms such as high fever, headache, general malaise, muscle pain, joint pain, loss of appetite and conjunctivitis. Other symptoms affect the respiratory tract, like cough, sore throat and nasal congestion. Sometimes, especially in children, it can affect the gastrointestinal tract, causing diarrhoea, nausea and vomiting. 

Generally, people with influenza recover without consequences, although in the case of elderly, frail or chronically ill people it can cause serious complications and sometimes can even be fatal.