Influenza, real flu, viral flu

Pathogenesis / course

Influenza viruses are surrounded by a shell called a Lipid double membraneon the surface of which there are various features that are visible as spikes under the electron microscope.

The two most important of these surface features are Hemagglutinin (Antigen H) and the neuraminidase (Antigen N). Based on these two characteristics, the type A flu viruses can be divided into different subgroups.

There are at least 15 different forms of hemagglutinin and 9 types of neuraminidase that are known to date in influenza type A. The so-called swine flu or Mexican flu, which was rampant worldwide in winter 2009/2010, is an influenza virus type A with the surface features H1N1. The pandemic of 1918/1919, the so-called Spanish flu, was also an influenza virus type A with the characteristics H1N1.

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You might also be interested in: What is the difference between a cold and the flu?

Illustration course of a flu

Illustration course of a flu

Course of flu
(Influenza viruses)
(Duration up to 14 days)
I - infection
Incubation period (1-2 days)
H - sore throat
Strong swallowing

S - runny nose
K + G -
Head and Body aches
Strong head, muscle, and
Body aches

F - fever
high fever (often over 40 ° C)

tR - dry, irritating cough
fH - stubborn cough
General condition:
Tiredness, exhaustion
up to 3 weeks
You can find an overview of all Dr-Gumpert images at: medical illustrations

After contact with influenza viruses, they establish a connection to the cells of the via the hemagglutinins on their surface respiratory tract and mucous membranes. The hemagglutinin also causes the envelopes of the virus and the host cell to fuse so that the influenza virus can begin to multiply inside the cell. Viruses, such as the flu viruses, do not have their own metabolism and cannot multiply on their own without help. They need other cells to do this for them. This mainly distinguishes them from bacteria, which have their own metabolism and can reproduce independently.

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After the viruses have successfully replicated, they induce the cell to expel them. The surface feature neuraminidase blocks this mechanism so that the viruses do not get stuck on the same cell again with their contact mechanism hemagglutinin.

The body cell dies when the virus escapes, which among other things causes the symptoms of the disease, and the newly produced viruses swarm out and infect other cells.

Duration of symptoms

After being infected with the viruses that are the cause of the flu, the typical symptoms do not appear immediately.
The so-called incubation period follows, which is usually around 1-2 days lasts. During this time, the viruses are already spreading in the body, but are not yet causing any symptoms.

The symptoms start around two days after infection with the virus.
The sudden onset of fever is particularly important here.
How long the typical symptoms of the flu last varies from person to person.

In most cases the symptoms last about 5-7 days although it can take several weeks for all symptoms to go away completely.
This mainly depends on the body's own defenses that fight the virus.

If the immune system is strong, defense against the virus is relatively good.
For people with a weakened immune system, such as the elderly or people with previous illnesses or those taking certain medications, a full recovery can take longer and may require drug therapy.

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Read more on the topic

  • Flu medication
  • Flu viruses
  • Superinfection

Duration of fever

The fever, which usually occurs in attacks, is the main symptom of the flu.
After the influenza incubation period, it occurs and can occur very suddenly up to 40 ° C to reach.
In most cases, bouts of fever and chills alternate periodically and can appear until the symptoms of the flu resolve.
Typically, however, the first days of flu are particularly dominated by fever.

The individual course of the fever depends heavily on the person affected.
Children and adolescents usually develop a fever faster than adults.

The course of fever during the flu is called "remitting“Called fever. That means that the body temperature is around 1.5 ° to 2 ° Celsius fluctuates between the morning and evening hours.
The fever is usually higher in the evening than in the morning.

If the fever persists for several days, a doctor should be consulted so that, under certain circumstances, therapeutic measures can be undertaken to lower the fever.
Secondary infections can also be partly responsible for the increased body temperature and should be clarified as quickly as possible by the attending physician.

Read more on the topic: When should I see a doctor with a fever?

Duration in children

In contrast to a cold, which is uncomfortable for the affected child, but usually poses no danger, an infection with the "real“Flu is a serious illness.

However, the immune system of children and adolescents is usually strong enough to survive the disease without taking medication.

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By sparing the body with bed rest and a sufficient supply of fluids, the disease can already affect children after 5-7 days be finished.

In some cases, however, the weakening of the immune system leads to a so-called bacterial superinfection, which requires medical attention.

Pneumonia, myocarditis or meningitis are diseases that should be treated with antibiotic therapy over time and are serious complications of influenza.

Children who suffer from previous illnesses that weaken the immune system or who suffer from illnesses that worsen significantly when infected with the virus are, according to the Standing Vaccination Commission (STIKO) classified as a risk group.
A bacterial superinfection should be avoided in these children.

If the infected person belongs to this risk group, the course of the flu can take significantly longer compared to children whose immune system is intact.
In these cases it can up to 2 weeks take to make a full recovery. For this reason, a vaccination against the virus is strongly recommended, especially for children who belong to this risk group.

Side effects often occur after such a vaccination. To do this, read the following topic: Side effects of a flu shot

It is also important that children are contagious a little longer than adults who are affected by the flu virus.
Adults are up to 5 days after the onset of the symptoms contagious to their environment, this period being up up to 7 days expanded in children.
This is important information, especially for those caring for children.

Additional information

  • flu
  • Influenza
  • Flu duration
  • Flu diagnosis
  • Flu story
  • Flu incidence
  • Flu vaccination
  • Flu complications
  • Flu forecast
  • Flu symptoms
  • Flu cause
  • Prevent flu

More information on this topic:

  • cold
  • Sore throat
  • sniff

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