Influenza is a common infectious respiratory disease caused by the influenza virus, also known as the Influenza virus, which affects millions of people worldwide every year.
Influenza is a contagious respiratory disease caused by influenza viruses. It can have moderate to severe consequences, sometimes even leading to death. The flu is different from a cold, it starts suddenly and violently, while cold symptoms gradually increase in intensity.
Incubation period of influenza
In influenza, the incubation period varies between 1-4 days. Adults can infect other people even before the onset of symptoms (1 day before symptoms appear). The contagious period usually lasts up to 5 – 7 days after the onset of symptoms, but it can exceed a week in some people, especially young children (up to 5 years) and people with a weakened immune system.
Influenza is characterized by the sudden onset of signs and symptoms such as fever, myalgia, headache, malaise, nonproductive cough, sore throat, and rhinitis. Among children, the flu is often associated with otitis media, nausea and vomiting.
The flu usually goes away 3-7 days after the onset of symptoms, but the cough and general malaise can persist for even more than 2 weeks.
How many days are you contagious if you have the flu?
Adults generally become contagious about a day before symptoms appear and remain so for 5 to 7 days after the onset of illness.
The highest risk of transmission occurs in the first 3-4 days after the onset of symptoms, when the viral load in respiratory secretions is the highest. During this time, the virus spreads easily through coughing, sneezing or talking, especially in closed and crowded spaces.
In the case of people with a weakened immune system, the contagious period can be longer. They can transmit the virus even after 7 days, especially if the fever persists or the symptoms are severe.
Children, especially young children, can shed the virus for a longer period, sometimes more than a week. Their still-developing immune systems and abundant secretions make them more contagious than adults.
Influenza type A vs. B
Differentiating between types A and B may seem like a medical subtlety. In reality, these categories explain why:
- some strains cause major epidemics
- others circulate only in humans and are more predictable
Influenza A
It is the most variable form. It infects humans, birds and mammals. The virus changes rapidly, which is why it can generate pandemics. The best known example is H1N1.
Influenza B
It circulates almost exclusively in humans and is genetically more stable. This form produces seasonal epidemics, being often found in children’s communities.
Similarities between influenza A and B
Although they differ in severity and behavior, there are common elements that define all three types:
- are respiratory viral infections
- they are spread quickly through the air, coughing, sneezing and direct contact
- can cause fever, muscle pain, tiredness and dry cough
- can be prevented by hygiene measures and vaccination
- they can affect people of any age
The similarities are especially visible in the first 24-48 hours after the onset, when the patient notices a fever and an altered general condition, but the subsequent evolution differs greatly depending on the type of virus.
Influenza A – the most widespread and unpredictable form
Causes of influenza A
Influenza A virus is notable for its unique ability to undergo rapid and frequent mutations. This genetic instability explains the emergence of subtypes such as H1N1, H3N2 and many others. Influenza A can also pass from animals to humans, which increases the risk of the emergence of completely new strains against which the population has no immunity.
This mechanism makes influenza A the most difficult to predict and also the most dangerous.
Symptoms of influenza A
Symptoms are usually intense and very quick:
– high fever
– severe muscle pain
– chills
– strong dry cough
– throbbing headache
– marked exhaustion
– sometimes nausea and vomiting, especially in children
Patients often describe feeling like they “don’t have the energy to stand.”
Treatment of influenza A
Antiviral treatment is often recommended, especially in the first 48 hours, to shorten the duration of the illness and reduce the risk of complications. Recommended measures include:
– constant hydration
– absolute rest
– antipyretics (paracetamol)
– avoiding aspirin in children
– careful supervision of vulnerable people
Influenza B – stable but responsible for many seasonal epidemics
Causes of influenza B
Influenza B is caused by the Influenza B virus, which only circulates in humans. It is more predictable and stable than influenza A, but even so it can generate large epidemics, especially in schools and communities.
Symptoms of influenza B
Influenza B is usually milder than influenza A, but it should not be underestimated:
– moderate fever
– sore throat
– persistent cough
– marked fatigue
– less severe muscle pain
In young children it can cause complications such as otitis, sinusitis or bronchitis.
Treatment of influenza B
Many cases are treated symptomatically, but antivirals may be useful in vulnerable individuals. It is recommended:
– lots of liquids
– antithermic
– rest
– monitoring of children and the elderly.
