Influenza

What is influenza?

Influenza virus infections are common worldwide. In the northern and southern hemispheres, influenza waves occur regularly during the respective winters. The causative agents of influenza are orthomyxoviruses, which are subdivided into types A, B and C. Only influenza A and B viruses are relevant for humans.

Where do influenza viruses occur?

Influenza A viruses are found in humans and also in mammals (pigs, horses). However, the actual reservoir of influenza A viruses are birds, especially waterfowl.

How does infection occur?

Influenza viruses are transmitted mainly by droplets that are relatively large (> 5 µm), e.g. when speaking, but especially when coughing or sneezing. These can reach the mucous membranes of contact persons over a short distance. The incubation period (time from ingestion of the pathogens to illness) is 1-3 days.

Duration of infectiousness

Contagiousness begins shortly (< 24 hours) before the onset of clinical symptoms and usually persists for 3-5 days thereafter. Young children may shed virus earlier and for longer periods than adults.

What symptoms occur:

• sudden onset of illness with fever (≥ 38.5 °C),
• dry, irritating cough,
• Muscle and/or headache, sweating, sore throat, general weakness.

Complications occur mainly in elderly persons with underlying diseases, (chronic heart or lung diseases, metabolic diseases such as diabetes, immunodeficiencies, etc.). Pneumonia (pneumococcus, Haemophilus influenzae, staphylococcus) can develop especially in them. In children, inflammation of the middle ear (otitis media) can occur.

How can I protect myself?

One of the most effective preventive measures is vaccination against influenza, which should be done annually, preferably in the months of October and November. However, in case of an imminent wave of influenza, vaccination is possible and useful even later. Target groups of the vaccination (according to recommendations of the STIKO):

How do I behave towards patients and contact persons?

The spread of the pathogens should:

• by covering mouth and nose when coughing/sneezing and
• observance of careful hand hygiene.

As a general rule, respiratory secretions should be absorbed in disposable wipes and then disposed of hygienically. When caring for family members at home, it should be noted that unvaccinated persons and those who are individually particularly at risk (e.g., infants, the elderly, the immunocompromised, the chronically ill) should be kept away from the persons who are ill.

In the case of outbreaks in hospitals or homes for the elderly (compulsory notification in accordance with § 6 IfSG):

• the rapid recognition of the disease on the basis of a case definition including laboratory diagnostic confirmation,
• as well as the consequent isolation of ill or suspected persons. If necessary, chemoprophylaxis with suitable viral drugs should be carried out in consultation with an occupational physician and the Office for Health and Consumer Protection for unvaccinated contact persons or contact persons for whom the time interval between vaccination and illness is too short and therefore vaccination protection does not yet exist.