Avian influenza: spread, transmission, symptoms

The bird flu first appeared as such in 1978 in Italy. Following major waves of infection in Germany in 2006 and 2009, isolated cases of a new virus type (H5N5) have been detected since November 2016, especially in Lower Saxony.

What is bird flu?

Avian influenza, also known as avian influenza or avian influenza, is a worldwide, viral-transmitted infection that affects mainly chickens, turkeys and ducks, and more rarely wild birds, pheasants and guinea fowls.

The disease can be transmitted from animal to animal, via the faeces as well as the air and ends fatally for 80 to 100 per cent of the affected animals. The disease breaks out in poultry about 3 to 14 days after infection.

Symptoms in the affected animals are:

  • high fever
  • breathing problems
  • Frustration and fatigue
  • diarrhea
  • Black coloring of comb and wattles

Sometimes, however, the pathogen is so aggressive that the affected animal falls dead or suffocated without warning.

Avian flu: danger to humans?

For humans, most avian virus types are usually not dangerous. However, mutations such as the virus subtypes H5N1, H7N9, or the H5N5 pathogen can cause humans to become infected in animals.

After infection, such a virus can cause a serious illness, similar to pneumonia. In some cases, such an infection with the bird flu virus may even be fatal.

Below are several subtypes of bird flu listed in descending danger to humans:

  • H5N1 (also called type A)
  • H7N7
  • H7N9
  • H7N2
  • H5N8
  • H5N3

Transmission of bird flu to humans

Since the virus types H5N1 and H7N9 are particularly aggressive, the infection with these pathogens is more likely than others. According to the World Health Organization (WHO), since 1997, two small epidemics have already broken out, in which 18 people in Germany have been infected, in six cases, the infection was fatal. Worldwide, about 300 deaths are known only in connection with the subtype H7N9.

So far, experts believe that transmission from infected poultry to humans is via feces and blood spatter, but most likely not through eating infected meat.

The former also explains that transfers to humans took place mainly in Asia: on the one hand, people often live there very closely with poultry, on the other hand, it is common to offer and prepare chickens very fresh shortly after slaughtering in the market. According to the WHO, in Southeast Asia, especially those who had contact with the animals during slaughter, plucking or cooking.

What symptoms do infected people have?

An infection with avian influenza can occur in different ways in humans. The spectrum ranges from cases without signs of disease to a fatal ending form. The symptoms such as fever, cough and cold are similar to those of a normal flu or cold. The infection can not be detected without further blood tests.

If you are suspected of having an infection with bird flu you should seek medical help immediately and avoid contact with other people for their protection.

Possible symptoms of bird flu are:

  • fever
  • Cough (until breathlessness)
  • irritated mucous membranes (possibly nosebleed)
  • Limb and muscle pain
  • diarrhea
  • Vomit
  • headaches
  • fatigue
  • inertia

Treatment of bird flu in humans

If you are infected with any of the virus types, you may be given the flu medicines Tamiflu® and Relenza®. Although these medicines are not special agents against the avian influenza virus, but can prevent the proliferation of new influenza viruses in the body and thus accelerate the healing process.

Virostatic agents, ie virus-killing drugs, are used against the viruses themselves. Against the other complaints analgesics and antipyretics can be taken.

Prevent infection with bird flu

Those who want to be completely safe during a disease outbreak should avoid poultry markets and poultry farming.

Even those who find sick or dead birds, should never touch them, but inform the responsible veterinary office immediately. You do not have to be afraid of pigeons in public spaces, they are extremely rarely affected by avian influenza.

The incubation period for bird flu, in contrast to normal influenza, only two to eight days. After that, she is usually contagious for other people for one week. Therefore, one should avoid contact with infected people in order to prevent contagion. After detecting an infection with the bird flu virus, it should be clarified with a doctor whether the infected person should be quarantined.

Hygiene rules when handling poultry meat

Cooked or otherwise heated foods are considered to be free from pathogenic viruses. Freezing does not inactivate the virus. In this context, reference should therefore be made to the most important hygiene rules when dealing with poultry meat:

  1. Poultry meat should always be well cooked (over 70 degrees Celsius).
  2. All work surfaces and kitchen utensils that have come into contact with raw meat must be rinsed well, if possible under running water.
  3. Always change the wiping and rinsing cloths that have come into contact with raw meat.

Spread of bird flu among domestic poultry

The likelihood of transmission of highly pathogenic virus species by migratory birds to domestic poultry by direct route is considered rather low. More likely is a natural, slow virus spread through the overlap of duck breeding grounds.

In case of outbreaks of disease, however, it is particularly important to sensitize the population to the risk of the virus being introduced. Attempting to import illegal poultry imports, smuggling songbirds or unwittingly hauling in the virus are the main threats to their spread.

Poultry farmers on alert

In the event of an outbreak of bird flu among poultry, all measures laid down in the Avian Influenza Regulation will be initiated.

These include at disease outbreak:

  • barring
  • shipment bans
  • immediate killing and destruction of the poultry
  • the establishment of restricted areas and observation areas

Vaccine against avian influenza?

A vaccine for poultry to protect against avian influenza exists, but is controversial. While live vaccines carry the risk of mutating viruses, inactivated vaccines may present a risk that vaccinated animals will not show symptoms but still re-distribute the virus.

A working group at the Institute of Molecular Biology at the Friedrich-Loeffler-Institut on the island of Riems has succeeded in developing a vaccine against avian influenza, which is based on a genetically modified form of a vaccine strain against another poultry disease (Newcastle disease) and thus the excludes the above risks. However, after the first successful series of tests, further tests have yet to be made before approval.

Mutation of the viruses - the big concern

Concern makes it possible that avian influenza viruses could combine with a conventional flu virus to form a new pathogen. Such a human pathogenic agent could be transmitted from person to person, thereby risking a major epidemic.

Pigs and horses could also be hosts in which new virus strains can develop.

Conclusion: Dangers of avian influenza are rather low for humans

In Germany, sufficient safety precautions are currently in place to prevent or stem the emergence of waves of bird flu. The risk of transmitting the virus from birds to humans is generally very low. If somebody is still infected with one of the various avian influenza agents, you can usually treat it very well today.

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