Introduction
The duration of a flu depends on the severity of the infection and the type of pathogen. The real flu is the influenza, which is caused by the so-called influenza viruses. The real flu usually lasts for 7 to 14 days and is characterized by a sudden onset of the disease.
However, a feeling of weakness can last for several weeks. Influenza can also have a longer and more severe course. This is the case, for example, when there is an accompanying pneumonia.
Such an influenza pneumonia occurs mainly in immunocompromised persons with previous illnesses. Furthermore, heart muscle inflammation (myocarditis), encephalitis and myositis can also occur. These then prolong the course of the disease.
In principle, they can occur with any type of influenza, but as a rule they particularly affect people with previous illnesses, diseases of the immune system or patients under immunosuppressive therapy. They can also lead to encephalitis and inflammation of the muscles. The course of the disease can also be prolonged by bacterial superinfections.
Because the body is weakened in the course of the viral infection, bacteria can settle, leading to further infections and thus to a longer course of the disease. The “real flu” must be distinguished from “flu-like infections”, which are usually caused by other viruses or, more rarely, by bacteria. Mostly they are banal colds, which heal after an incubation period of about two to eight days after 10 days of disease progression.
In everyday language, the terms are often used synonymously, although they are actually independent clinical pictures. With a flu-like infection, a distinction is made between different pathogens that can cause it. In addition one differentiates between a “summer” and a “winter flu”, which also show different courses.
A flu is first preceded by the so-called incubation period of the pathogen. The incubation period is the time between infection with the pathogen and the appearance of the first symptoms. With the genuine flu the incubation period is very short with 1 to 4 days.
The beginning of the disease is sudden. The flu shows no characteristic phase progression. After the incubation period, symptoms appear suddenly, which are similar to the symptoms of a cold, but are usually more pronounced.
Typically, the infection begins with a general feeling of illness, shivering, fever and sore throat. The course of the disease usually lasts 7 to 14 days and heals well. Strictly speaking, flu-like infections are not a flu but a disease in their own right.
However, since they are often equated with a flu in general usage, they are listed here for the sake of completeness. Influenza infections are mostly caused by viruses, such as the rhinovirus or adenovirus. However, there are over 200 pathogens that can cause a flu-like infection.
The incubation times of the individual pathogens differ slightly, but are approximately between 2 and 8 days. The onset of the disease is rather insidious. A healing is to be expected after 10 days at the latest.
The symptoms of influenza last about 10 to 15 days in total. They include high fever (up to 40°C), chills, sore throat, dry cough, aching limbs and general weakness, loss of appetite, nausea and vomiting. Usually the first sign of flu is a sudden high fever, which is accompanied by a strong feeling of illness.
The fever lasts for about 4 days. A renewed rise in fever on the third day may indicate a bacterial superinfection. This is accompanied by sore throat, dry cough and loss of appetite.
These symptoms can last up to two weeks longer than the fever, but usually subside after 10 to 15 days. A general weakness can often persist for several days after the flu has healed. The symptomatic course of influenza varies greatly from individual to individual.
In most cases, the course of the disease is mild and harmless. Only in rare cases do serious, life-threatening courses occur. Nevertheless, influenza should be taken seriously.
In particular with existing previous illnesses, children or very old people, severe courses of the disease can become apparent. The course of a bacterial superinfection can be more serious and protracted.This means that those affected become additionally infected with bacteria due to a weakened immune system at the bottom of the influenza. Here, further symptoms can be added, which can prolong the course of the disease beyond two weeks.
The symptoms of influenza infections tend to start slowly and usually subside after 8 to 10 days without any complications. Even in the case of flu-like infections, it is not possible to determine a classic phase of the disease. In most cases, mild symptoms such as rhinitis, coughing and a general feeling of being ill occur during a flu-like infection, which do not show a stage-like course. High fever usually does not occur.
