The (real) flu (influenza) is a disease of the respiratory tract – nose, throat and lungs – caused by influenza viruses. Colds or “flu-like infections,” on the other hand, are caused by other pathogens. Influenza viruses belong to the group of orthomyxoviruses. Types A and B cause the seasonally occurring disease waves, yet type C is marginally relevant for humans. Influenza A and B viruses are a worldwide threat. In Germany, the number of diseases increases particularly in the winter months, during which an estimated 5 to 20 percent of the population is infected with the virus. As influenza viruses are continually changing, people can become infected and ill with influenza several times in the course of their lives.
Seasonal influenza is transmitted from person to person, or from area to area via droplets. The virus is highly contagious. When infected people sneeze, cough, or speak, small, virus-containing droplets of the nasopharynx secretion are released into the air. These can be inhaled by people nearby and infect them. Such transmission of the flu is possible from one day before symptoms occur, and up to 5 to 7 days after the onset of the disease.
The severity and length of influenza depends on many factors, including the age of the person affected. An infection can be mild or completely symptom-free, but there are also serious illnesses that – in the worst case – can lead to death. The incubation period of influenza following infection is 1 to 2 days on average. Then infected people fall ill relatively abruptly. A sudden feeling of weakness is typical of influenza. Other symptoms include fever, chills, coughing, and fatigue, as well as headaches and muscle aches. Usually the symptoms subside after 5 to 7 days. The most common complications include pneumonia. Children can also develop middle ear infections. Inflammation of the brain or the heart muscle occurs rarely.
Influenza viruses are pathogens that must be reported in many countries. As nosocomial pathogens, along with noroviruses and rotaviruses, they are frequently viral causes of outbreaks. The proportion of influenza patients who are hospitalized is around 17 percent.
1 to 2 days
The necessary spectrum of activity against influenza viruses is: limited virucidal