# Influenza

Classification according to ICD-10
J09 Flu due to avian influenza viruses that have been proven
J10 Influenza from other known influenza viruses
J10.0 Flu with pneumonia, other influenza viruses detected
J10.1 Flu with other manifestations on the respiratory tract, other influenza viruses detected
J10.8 Flu with other manifestations, other influenza viruses detected
J11 Flu, viruses not detected
ICD-10 online (WHO version 2019)
Influenza virus

The influenza , also (genuine) flu or influenza called, is a predominantly by viruses from the group of Orthomyxoviridae and the genus Influenza virus induced febrile A or B infection in humans. The flu is usually epidemic and involves the respiratory tract.

## Occurrence

The influenza viruses and the diseases they cause exist worldwide, but in contrast to the other virus types (especially A), the influenza C and D viruses are very rare as causative agents of the virus flu. The infection is also "sporadic", ie outside of epidemics and pandemics , very frequent: According to estimates by the World Health Organization (WHO), 10 to 20% of the world population is affected every year. At the age of six, for example, almost all children in the Netherlands have had infections with at least one of the virus subtypes. In Germany, at the end of the 2017/2018 season, in which the highest number of cases had been reported since 2001, a total of around 334,000 cases of outpatients with virus detection were reported. The influenza viruses “circulate” in the northern hemisphere mostly from the beginning of October to mid-May.

## Working Group Influenza

The Influenza Working Group (AGI) is based in Germany and was founded in 1992 by four pharmaceutical companies and the German Green Cross (DGK), which is also close to the industry. After the Infection Protection Act came into force (early 2001), the Robert Koch Institute (RKI) took over the scientific leadership of the AGI while retaining the previous sponsors DKG, Aventis Pasteur MSD, Chiron Behring, Niddapharm, SmithKline Beecham Pharma and Solvay Arzneimittel. In response to the early phase of the H1N1 2009/10 pandemic ("swine flu"), the RKI has been solely responsible for the Influenza Working Group since winter 2009/10. Since then, the AGI has been a community of Sentinel practices and the RKI, whose work is financed exclusively from public funds. The RKI describes the AGI on its website as follows: “AGI is a network of around 700 general practitioners and paediatricians who together care for around one percent of the population. Throughout the year, you voluntarily and on a weekly basis inform the Robert Koch Institute of the number of acute respiratory diseases in your practice. On this basis, the experts at the RKI determine the burden of disease through acute respiratory infections in the population - especially through influenza. ”The AGI publishes a. a. Weekly and seasonal reports in which the data recorded on the course of the disease in Germany are recorded and evaluated.

## transmission

The virus enters the body through the lining of the airways, mouth, and eyes. It reaches these entry points

• through droplet infection, i.e. through the contact of the mucous membrane with expiratory droplets that occur when infected people sneeze, cough, speak or breathe. The larger, infectious droplets sink within about two meters and stick particularly firmly to rough surfaces. However, if the expiratory droplets are already drying in the air, the very small viruses contained in them with a diameter of approx. 0.1 µm can float as an aerosol (also called droplet cores or airborne ) over long distances in the air and remain infectious for hours. Dry indoor air in heated rooms promotes this aerosol formation and can be a reason for the occurrence of flu waves in winter.
Infected people can greatly reduce the droplet emission by wearing respiratory masks, as the fresh droplets stick well in the filter material right in front of their mouth. A counter air flow can protect against infection via the aerosol. Simple breathing masks over the mouth and nose partially hold back the viruses transmitted as aerosol, but not reliably because the filter materials cannot completely hold back viruses, the masks do not fit tightly enough and do not cover the eyes at all. Ventilation can reduce the risk of infection by diluting the aerosol concentration in the room if the aerosol does not get into other living spaces in the building.
• Via contact infection or smear infection with viruses that get onto objects in exhaled droplets or through smeared nasal secretions or contact from infected people and are particularly easily transferred from smooth surfaces via the hands to their own mucous membranes within two days.
• due to faecal particles from diseased hosts and vectors
• by viruses on dander, hair, plumage and dust
• through contact with the saliva of sick people

The virus is insensitive to dehydration and remains infectious for longer at low temperatures and low humidity.

temperature humidity Surroundings time source
(° C) (% RH) active contact infectious
<0 in the ice unlimited
0 > 30 d
? smooth surfaces such as stainless steel or plastic 24-48 h <24 h
? Textiles, paper, paper handkerchiefs 8-12 h <15 min
? Banknotes 1–17 d
20th on surfaces in air 2-8 h
21st 20th as an aerosol in air ${\ displaystyle t_ {1/2}}$ > 60 min
40 ${\ displaystyle t_ {1/2}}$ = 56 min
70 ${\ displaystyle t_ {1/2}}$ = 28 min
22nd in the water > 4 d
34 on hands <5 min
56 <3 h
60 <30 min
> 70 few seconds

t ½ = half-life

The incubation period is 1.2 to 4 days, depending on the examination, method or virus subtype.

## Course of the disease / symptoms

As a rule of thumb, about a third of influenza infections are febrile , another third are milder and the last third are without noticeable symptoms. By far not all people infected with influenza fall ill, even fewer fall ill with typical symptoms . The first symptoms, if any, appear after an incubation period of a few hours to days, but the viruses can be transmitted to others two days before the first symptoms appear. If the symptoms are rather unspecific, influenza can be confused with other acute respiratory diseases. A table for differentiating between influenza and cold can be found under cold . The main symptoms of influenza are:

• sudden onset of illness
• pronounced feeling of illness throughout the body
• Fever of over 40 ° C, also with chills
• pronounced malaise with headache and body aches
• dry cough

Possible, but less characteristic of influenza are:

Usually symptoms last 7 to 14 days. However, a general feeling of weakness and loss of appetite may occur for a few weeks after this.

## Complications

The dangerous thing about influenza is often not the virus itself, but the bacterial secondary infection that can follow a flu. Since the organism is already weakened by the virus infection, bacteria can more easily penetrate the body, multiply and lead to further diseases. The colonization of the airways previously damaged by the virus with pneumococci is particularly common . The pneumococcal pneumonia that then develops can be life-threatening, especially in patients with chronic diseases and in the elderly. Pneumococcal vaccination combined with influenza vaccination lower the risk of pneumococcal pneumonia and fatal outcome compared to pneumococcal vaccination alone, influenza vaccine alone, and placebo. Other complications are primarily virus-induced pneumonia (influenza pneumonia ), brain inflammation ( encephalitis ), inflammation of the skeletal muscles ( myositis ) as well as myocarditis ( myocarditis ) and heart attacks . They occur primarily in people with a risk factor such as chronic cardiopulmonary diseases, metabolic diseases and immunodeficiencies and can lead to death within a few hours (peracute).

## Influenza and pregnancy

During pregnancy, the immune defense is reduced, which prevents excessive immune reactions against the foreign protein of the embryo. Therefore, the risk of being infected with the virus during an influenza epidemic is greater for pregnant women than for non-pregnant women. There is also evidence that influenza infection can be more severe in pregnant women.

## Diagnosis

The diagnosis is usually made from a nasal swab from the posterior nasal cavity or from the classic deep throat swab. Other examination fluids are tracheal secretions , bronchoalveolar lavage (BAL), nasal irrigation fluid, throat irrigation fluid or the blood.

## therapy

A number of specific antiviral drugs are available to treat influenza virus infection. To a limited extent, these can shorten the disease and prevent life-threatening complications in vulnerable patient groups. All antiviral drugs require a prescription , among other things because they should not be used in non-vulnerable patients in order to avoid the development of resistance from virus strains. Significant side effects have also been observed and the time of use and certain important contraindications must be observed.

In addition to the specific therapy for influenza, the symptoms of the patient are also treated symptomatically. This symptomatic therapy is intended to prevent the development or progression of complications and alleviate the mostly unpleasant symptoms such as fever, chills, obstruction of the airways or lability of the cardiovascular system. They have no influence on the replication, elimination or transmission of the virus.

### Antiviral therapy

Drugs from different substance classes are approved for influenza therapy in humans: the inhibitors of the viral membrane protein ( M2 ), which acts as a proton pump to protect the viral hemagglutinin from low cellular pH values , and the neuraminidase inhibitors , which were developed only a few years ago inhibit the activity of the viral surface enzyme neuraminidase and thus block the release of the virus when it is released from the cell. The viruses cannot infect any other cells. Another treatment option is endonuclease inhibitors, one of which has so far been approved in Japan.

Since antiviral substances only intervene in the replication of the viruses, viruses already in the body cannot be inactivated by them or prevented from infecting other cells. As a result, the success of antiviral therapy also depends on timely use. If the time of the appearance of the first signs of illness (symptoms) is presumably more than 48 hours ago, the influence of these active substances on the course of the disease is only minimal; therefore, taking is no longer recommended.

Resistant virus strains were already in circulation in 2009. Seasonal influenza A / H1N1 is 96% resistant to oseltamivir , 2% to amantadine , but not to zanamivir . The pandemic influenza A / H1N1 previously had the H275Y mutation responsible for resistance to oseltamivir only in individual local cases. Influenza A / H3N2 has almost 100 percent resistance to amantadine, while oseltamivir and zanamivir are still effective. Influenza B is not yet resistant to any of the substances.

#### M2 membrane protein inhibitors

The M2 membrane protein inhibitors (M2 inhibitors for short) include amantadine (in Germany PK-Merz as well as generics from e.g. AL , Hexal , Neuraxpharm ) and rimantadine (trade name Flumadine ), which is only conditionally approved on the basis of a civil protection exception regulation under the Medicines Act of 2003 ). The M2 inhibitors to be taken as film-coated tablets are usually less well tolerated than the neuraminidase inhibitors, which is why they are no longer the drug of first choice. Influenza viruses evolve to amantadine quickly resistances that can be passed on as a new infectious and resistant viruses. The M2 inhibitors are particularly important in connection with the prophylaxis and treatment during a possible influenza pandemic.

#### Neuraminidase inhibitors

Representatives of this class of substances available to date have an unfavorable ratio of (low) effectiveness and (significant) side effects. There are currently three neuraminidase inhibitors approved in the EU, but not everywhere on the market: oseltamivir, zanamivir and peramivir. Oseltamivir (trade name Tamiflu ) is used orally as a suspension or capsule and is approved in Germany for therapy and prophylaxis from the first year of life. Outside of a particular pandemic situation, prophylaxis can be carried out with oseltamivir in people at risk if there is no vaccination protection and there is a simultaneous possibility of infection. This also applies to people at risk who cannot tolerate a vaccination against influenza (e.g. due to an allergy to chicken protein). In 2017, the WHO downgraded oseltamivir from “essential” to only “complementary” because of its low effectiveness and significant side effects. Zanamivir (trade name Relenza ) is only available as an inhalation powder. It can be used for timely therapy from the age of five. Peramivir, which is to be used as an infusion, is not available in Germany.

#### Endonuclease inhibitors

The influenza virus has a polymerase complex. This consists of three proteins: PB1, PB2 and PA. PB1 and PB2 are the "polymerase basic protein 1 and 2". PA is the "polymerase acidic protein". All are essential for virus replication. PB2 connects to the tip of the host's pre- messenger RNA to allow the viral RNA to replicate. The PB1 inhibitor favipiravir ( Avigan ) was approved in 2014 in Japan for the treatment of influenza. Pimodivir is a PB2 inhibitor for influenza A viruses. In 2018, a selective PA inhibitor, baloxavirmarboxil , was successfully tested in an international study on adults and adolescents with uncomplicated influenza.

### Herbal medicine

To prevent infections with viruses ("infection blockers"), preparations for sucking are offered, for example with cistus extract . Polyphenols from rockrose are supposed to bind virus particles in a non-specific manner and denature the proteins in the virus envelope. Clinical efficacy against influenza viruses could not be convincingly demonstrated. Certain mustard oil glycosides from nasturtium and horseradish root , for which a broad spectrum of antibacterial activity against pneumococci and other problematic pathogens has been proven in vitro , can alleviate the symptoms caused by possible secondary bacterial infections of the respiratory tract.

### Symptomatic therapy

An additional bacterial infection caused by influenza in the form of a purulent sore throat, acute bronchitis , pneumonia or meningitis can be countered by antibiotic therapy that is as specific as possible . In the case of some influenza infections with a longer course of the disease, if the virus infection has already been overcome, usually only the bacterial infection is in the foreground.
The course of the disease can be positively influenced by additional measures such as adequate fluid intake (considerable water loss due to fever), adequately humidified air, inhalation , and the administration of drugs that cause the nasal mucosa to swell.

As further symptomatic measures, fever-lowering agents (particularly in the case of circulatory lability or heart disease) such as paracetamol and ibuprofen are administered. The use of acetylsalicylic acid (ASA) in children under twelve years of age should only be carried out on a doctor's prescription, since a viral infection poses a risk of the dangerous, often fatal Reye's syndrome .

Since numerous influenza-related damage to the lungs and subsequent deaths are attributed to an overreaction of the immune system ( cytokine storm ), researchers are working on the development of substances that regulate the immune reaction in the case of influenza.

## prevention

### hygiene

Even simple hygienic measures can significantly reduce the frequency of influenza infections during a flu epidemic without pharmaceutical preparations. For example, unwashed hands should not touch the nose or mouth or rub the eyes. In addition, shaking hands in general and any other physical contact with infected people in particular should be avoided and the risk of virus transmission should be reduced by frequent washing of hands with standard cleaning soaps and disinfecting contaminated surfaces. Wearing mouth and nose protection also lowers the risk of spreading or ingesting pathogens, but in Europe, unlike in Asia, for example, it is not common in public. When admitted to hospital, influenza patients can be isolated to prevent exposure , and those infected by the same virus type can also be isolated in cohort isolation .

### vaccination

A flu vaccination is considered to be the most effective preventive medical measure against influenza, even if the vaccines currently available are not optimal because their effectiveness varies greatly from season to season . As a rule, an annual boost of immunization is necessary because influenza A viruses are very versatile. This is why vaccination campaigns take place before the expected flu season, in the northern hemisphere preferably in October and November. One of the most dangerous complications of influenza is the superinfection of the airways previously damaged by the virus with bacteria, especially pneumococci . The pneumococcal pneumonia that then develops can be life-threatening, especially in patients with chronic diseases and in the elderly. Pneumococcal vaccination combined with influenza vaccination lower the risk of pneumococcal pneumonia and fatal outcome compared to pneumococcal vaccination alone, influenza vaccine alone, and placebo.

### Vitamin D

Meta-analyzes have shown that it has not yet been proven that infections with the influenza virus or even clinically manifest influenza diseases are favored by vitamin D deficiency, nor that the substitution of vitamin D or its active metabolites reduce the risk of both . Nevertheless, dietary supplements containing vitamin D are being advertised as possible protection against flu.

### Neuraminidase inhibitors

For post-exposure prophylaxis and therapy for symptoms such preparations may oseltamivir and zanamivir are applied. However, their effectiveness is low, on average they only reduce the duration of influenza by less than a day.

## Historical

The name “influenza” ( it. For “influence”), which has been common in German since the first half of the 18th century , is probably derived from the medical - astrological notion that prevailed up until the Middle Ages that all diseases are influenced by certain planetary positions ( coeli influencia : influence of the stars), perhaps also from the influence of the influx of cold air currents.

The name has only been used in connection with the “real flu” since the 15th century. From the middle of the 18th century onwards, people spoke of the influence of the cold ( influenza di freddo ), since the disease was usually seen to occur in the cold seasons.

Names for this disease, which has been detectable in the westernmost part of Eurasia since the Middle Ages, differed greatly: male mattone (the raging disease, Italy 1580), lung addiction, brain pain, main disease (= head disease), brain-raging fever (1580), new breast disease (1602), sleeping sickness (1712), (epidemic) river fever (1730, 1762, 1782), epidemic catarrh, epidemic fever, Schnuppfieber (1782), Spanischer Ziep (1580), Spanish pips, Russian or Nordic epidemic or catarrh (1782), Die Russische, Die Nordic, maladie russe, catarrhe russe, la russe, the Siberian or Chinese disease (in Russia), disease à la mode (because of its widespread distribution), gallantry disease, fashion fever (1712), catarrhal disease (1730), fashion disease ( 1730, 1732, 1782), lightning catarrh (1782), le Tac (1413, presumably), le Horion (1413, presumably), Bremer Pip, Nürnberger Pipf (1580), Eiderstedtsche disease (1733), Coqueluche (1414), Ladendo ( 1427), Coquelucha (151 0), mood (1782 with a short and less aggressive course), chicken woe, chicken goat, sheep cough, sheep disease (1580), dog disease (1782), male della zucha (Italy 1580, pumpkin disease because of the severe headache), contagious or epidemic catarrh fever (1730), synoque catarrhale (1730), le grand rhume (1730).

Before transmission by viruses (the flu virus was discovered in 1933 by Patrick Laidlaw , Wilson Smith and Christopher Andrewes in the throat rinse water), the bacterium Haemophilus influenzae, discovered by Richard Friedrich Pfeiffer in 1892, was believed to be the cause of the flu or "influenza".

The history of virology is closely linked to the names Adolf Mayer , Dmitri Iwanowski , Martinus Beijerinck and Wendell Meredith Stanley , among others . Their work and the isolation and cultivation of the virus that causes influenza in humans by Christopher Andrewes, Wilson Smith and Patrick Laidlaw from the National Institute for Medical Research in 1933 were necessary in order to be able to take effective action against influenza (especially against the bacterial secondary infections as well antibiotics were not yet available).

The Times of London used a German-based word in a report on a flu epidemic in Koenigsberg and other parts of Prussia in 1833 :

"... a disease called the griep , or influenza"

It never appeared again in the paper afterwards. The older English medical literature knows the word "flu". "Influenza" was common in the early editions of the Times . A parliamentary report from 1785 stated:

"It is astonishing that Lord Mulgrave, as soon as he arrived at the House [of Lords], set off influenza, which manifests itself in the form of a concert of sneezing and blowing one's nose."

The “flu” common in German was probably borrowed from French at the end of the 18th century, where “la grippe” is derived from “gripper”, with the background that this disease suddenly grabs or grabs you. The word “gripper” in turn goes back to the same Germanic root as the German “gripping” ( Gothic “greipan”; Old High German “grîfan”). A derivation from the Russian "chrip" (хрип, rattle) is also possible.

In 1889 the Austrian daily newspaper described a so-called "Russian flu" spreading across Europe as follows (the existence of viruses was not yet known at the time):

“In the Vienna General Hospital there is no clinic or department where the waiting staff is free from influenza cases. […] Over 300,000 people were infected with it in Petersburg and Moscow. Influenza is spreading rapidly as no other disease, even cholera or yellow fever , can say. [...] According to Prof. Nothnagel in Vienna, the disease is undoubtedly a bacterial disease ; it does not spread through a contagium , but through the air by means of miasms . "

## Epidemics / pandemics

One speaks of an influenza epidemic , flu epidemic or flu wave when 10–20% of the population is infected and the outbreaks remain local or regional; a pandemic influenza is spreading all over the world. The cause of the epidemics and pandemics are viruses of the groups influenza virus A and - less often - influenza virus B , as these are able to constantly change their antigenic surface molecules hemagglutinin : H A and neuraminidase : N A. This means that the immune system can no longer or only poorly recognize them if the infection is renewed .

There have been descriptions of influenza epidemics since the 16th century. They are often described at the time of urbanization in the 19th and 20th centuries.

There were worldwide outbreaks (pandemics) in 1889 ( subtype A / H2N2 ), 1918 ( Spanish flu , subtype A / H1N1 ), 1957 ( Asian flu , again subtype A / H2N2), 1968 ( Hong Kong flu , subtype A / H3N2 ) and 1977 ( Russian flu , again subtype A / H1N1). Among other things, health authorities refer to this history , according to which isolated transitions of the bird flu H5N1 virus (subtype A / H5N1) to humans and the influenza pandemic 2009/10 give cause for concern. According to estimates by the Robert Koch Institute (RKI), around 25,100 people died in Germany as a result of the exceptionally strong flu wave of 2017/18 (around 2.7% of the 932,272 who died in 2017). This is the highest number of deaths in the past 30 years.

It is estimated that more than 400,000 people died in Germany as a result of the “Spanish” flu, around 29,000 from those of the Asian flu in 1957/58 and 350 from those of the swine flu in the winter of 2009/10 .

In the EU (and associated countries) the European Influenza Surveillance Scheme (EISS ) gathers country data on influenza diseases and evaluates them weekly. As early as 2012, Google was able to accurately predict the high points of some regional flu waves in the USA based on surfing behavior on the Internet .

Article on flu epidemics and pandemics on Wikipedia:

## Epidemiological surveillance

### Diseases

The epidemiological surveillance , also known under the English term surveillance , records the disease occurrence promptly through reporting systems. In many countries, voluntary networks of doctors have been set up, which continuously report certain illnesses to a central point. Data is also collected through diagnostic laboratories.

Every year the flu takes a severe course in around 3 to 5 million people worldwide. To a large extent, people in whom the disease is severe belong to the risk groups. These include pregnant women, children younger than 59 months, the elderly, people with chronic illnesses (e.g. chronic heart, lung, kidney, metabolic, neurodevelopmental, liver or blood disease), or people with disabilities the immune system (for example caused by HIV / AIDS , chemotherapy or use of steroids ).

In Germany, illnesses caused by influenza are determined and evaluated by the Robert Koch Institute with the involvement of volunteer doctors, German state examination offices, health authorities, universities and state laboratories. Between 2001 and 2009, between 629 and 1677 influenza cases were detected for the winter months. However, it can be assumed that the number of those actually suffering from it was also significantly higher in these years, since only some of the doctors participate in this reporting system and virological evidence was only carried out on patients with clear symptoms. In the 2014/15 season, for example, 70,247 diseases were detected. There were 77,712 reported cases in 2015 as a whole, compared to 63,572 in 2016. The Robert Koch Institute reported 96,000 infections in 2017, 274,293 cases in 2018 and 144,480 cases in 2019.

In Switzerland, the Federal Office of Public Health collects relevant information in the Sentinella reporting system and publishes it weekly in its bulletin. In the winter half-year, the number of flu-related consultations is reported based on all consultations with the reporting doctors. The national epidemic threshold, calculated on the basis of reports from the last 10 years, is 70 suspected flu cases per 100,000 inhabitants for the 2014/15 season.

The European Influenza Surveillance Network (EISN) is coordinated by the European Center for Disease Prevention and Control (ECDC). The network makes the results of epidemiological and virological surveillance of influenza available to public health decision-makers in EU Member States. A weekly analysis of influenza activity is published in Flu News Europe .

### Deaths

Mortality as a function of the age of the sick. Around 75 percent of the deceased were older than 65 years. (USA 2018/2019)

In numerous countries, causes of death are recorded by the statistical institutions in accordance with the international statistical classification for diseases , which is currently available in the ICD-10 version. In influenza, the classification differentiates between cases with virus detection (code J10), generally determined by virological tests in the laboratory, and cases without virus detection (code J11), based on a medical diagnosis.

In the cause of death statistics , the basic illness registered by the doctor is counted, but not the “immediate cause of death” or the “illness which also leads to death”. Therefore, deaths caused by influenza cannot be counted on the basis of the cause of death statistics. In determining the influenza-related mortality, an approach is used to calculate the excess mortality in the weeks or months with influenza circulation. The influenza-related deaths are then calculated from the difference between the actual and expected mortality. When the flu outbreaks, the number of actual deaths exceeds that expected. In this way, around 30,000 additional deaths were determined in Germany for the winter season 1995/96 and the number of 29,000 cases for the winter season 2012/2013. But since the turn of the millennium there have also been eight winters with no verifiable excess mortality. The Federal Statistical Office calculated an excess mortality rate of 2,200 deaths or 17 percent for Switzerland in the first three months of 2015, which it attributed to the flu epidemic that was taking place in Switzerland at the same time.

These calculations are estimates. They do not differentiate between deaths from flu, flu-like viral illnesses, or from secondary pneumonia. Respiratory syncytial virus (RSV) infections can also overlap with influenza waves. A study from the US suggests that there are significantly more deaths from influenza in this case; the excess mortality from influenza is three times higher than that from RSV. Usually chronically ill, elderly people are affected, who are at risk from the additional burden of flu.

In contrast, the influenza deaths counted directly in the cause of death statistics are insignificant. The Federal Statistical Office in Germany determined between 3 and 34 cases per year between 1998 and 2007 with virus detection (J10) and between 63 and 330 per year without (J11). According to the Austrian Federal Statistical Office, between 6 and 145 people died of the flu between 1998 and 2007 (J10-J11). Between 1998 and 2006, between 8 and 129 people died directly from the flu in Switzerland (J10-J11).

A 2017 study conducted by the WHO estimated the global annual deaths from influenza-related respiratory diseases at 290,000 to 650,000. Deaths mainly occur within the risk groups.

## Reporting requirement

In Germany, " zoonotic influenza" is a notifiable disease according to Section 6 (1) of the Infection Protection Act . You are required to report by name in the event of suspicion, illness or death. According to German law, zoonotic influenza has to be reported under the Measles Protection Act since March 1, 2020.

In Austria, "infections with the influenza virus A / H5N1 or another bird flu virus" are notifiable diseases according to Section 1 (1) of the 1950 Epidemic Act . The reporting obligation relates to suspected cases, illnesses and deaths.

In Switzerland, "Influenza A HxNy (new subtype)" is a reportable disease according to the Epidemics Act (EpG) in conjunction with the Epidemics Ordinance and Appendix 1 of the EDI Ordinance on the reporting of observations of communicable diseases in humans . The obligation exists in the event of clinical suspicion and extends to consultation with a specialist in infectious diseases and the initiation of pathogen-specific laboratory diagnostics.

## literature

Commons : Influenza  - collection of pictures, videos and audio files
Wiktionary: Influenza  - Explanations of meanings, word origins, synonyms, translations
Wiktionary: flu  - explanations of meanings, word origins, synonyms, translations

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