In infected commercial poultry low pathogenic influenza viruses of the subtypes H5 and H7 can mutate to a highly pathogenic form, which then occurs clinically as fowl plague. Infections with other subtypes usually proceed without grave clinical effects also in domestic poultry.

The term avian influenza is generally being used by the public at present to describe the fowl plague caused by the highly pathogenic H5N1 virus of the type Asia. The animal epidemic can also be transmitted to humans when there is very close contact with infected birds. Fowl plague has been spreading in Southeast Asia since the end of 2003. At the end of 2005 it was also found in Turkey and the first cases were confirmed in Germany in February 2006.

How is avian influenza transmitted?
It has been known since 1997 that avian influenza viruses can also be transmitted to humans if there is intensive contact with diseased animals. The virus is found in the secretions of the respiratory tracts of the birds. It is, however, mainly concentrated in the droppings of infected birds. Transmission to humans probably usually takes place through inhalation of dust particles containing the virus or through contact with animals when suitable hand hygiene is not practiced. In a few cases the virus is also transmitted by consumption of raw poultry products. Isolated cases of transmission from a sick person to other people through close contact are suspected. In a very few cases (e.g. in Indonesia) the infection route could not be clarified.

How can I tell the difference between a "normal" flu and avian influenza?
"The symptoms of avian influenza are different to those for normal flu," says Professor Michael Schmidt of the Faculty of Veterinary Medicine at the Free University of Berlin. "The symptoms are only similar at the beginning: The infected people complain in the first days of fever, coughing and muscle pain." A serious pneumonia then soon also breaks out.

The doctor of human medicine Bettina Temmesfeld of the Berlin hospital Charité also confirms: "Bird flu is generally more severe than a normal influenza - the lungs are affected much more strongly."

Professor Schmidt urges doctors to "examine the type of infection extremely carefully." Influenza quick tests show within half an hour whether a person has become infected with a flu virus. Whether the pathogen is the dangerous H5N1 virus has to be examined in a complicated process. This takes at least 12 hours. "The samples naturally also have to be examined several times," says Professor Schmidt.

Is avian influenza dangerous to humans?
Avian influenza is an animal disease and dangerous mainly for birds. It is not very dangerous for humans. There are many different avian influenza viruses, most of which are completely harmless for humans.

The avian influenza virus H5N1, which has now also been found in Germany, can infect humans. However, this happens very rarely and only in people who have intensive contact with infected poultry, in other words farmers and poultry breeders.

How is the diagnosis "avian influenza" made?
A doctor can suspect a possible "bird flu" on the basis of the patient's complaints (fever, coughing, breathing difficulties), information on journeys to and stays in a region with avian influenza, possibly contact with birds or poultry (see case definition of the Robert Koch Institute) and the results of a physical examination. The suspicion can be corroborated by influenza quick tests, which are used to detect components of the virus in the patient's saliva. The flu infection is proven by special tests (so-called polymerase chain reaction or PCR with prior reaction) carried out in specially equipped laboratories.

Is it possible to treat avian influenza with drugs?
Of the medicines effective against flu viruses, only the so-called 'neuraminidase inhibitors' Oseltamivir and Zanamivir have so far been shown to be effective against the current avian influenza virus H5N1. This knowledge is based on in-vitro studies, animal experiments and use on a small group of people. More extensive clinical experiences on patients with the H5N1 strain of bird flu are not yet available. Experts assume the neuraminidase inhibitors will be effective in the event of new pandemic influenza viruses that could stem from the bird flu virus.

Where in the world are there currently human cases of avian influenza?
The H5N1 epidemic amongst birds in Asia has led to diseases in humans in Vietnam, Thailand, Cambodia, Indonesia, China and most recently Turkey and Iraq since the end of 2003. Further occurrences of the disease in the near future especially in countries affected by the animal epidemic and their neighbors are likely. You can find a map showing the spread and number of human cases on the website of the European Commission. Almost all infected people had contact with diseased animals. Although it has not been safely proven, there are thought to have been isolated cases of human-to-human transmission.

Is avian influenza a danger to humanity?
Influenza viruses change constantly (so-called 'antigenic drift'). As a result vaccines have to be adapted constantly (annually) to the seasonal influenza. There is also the possibility that a concurrent infection with avian and human influenza A viruses in a human or pig could lead to a mixing (so-called 'reassortment') and drastic change in the genetic material of the viruses (so-called 'antigenic shift'). This could result in the protective mechanisms of the human body not being ready to fight the new pathogen, leading to a significant increase in the number of severe diseases with high mortality, as was the case numerous times in the last century. If the virus also becomes more easily transmissible from human to human, there is a danger of a worldwide spread and thus of a so-called pandemic.

Can I protect myself against avian influenza with a vaccination?
There is currently no vaccine available that protects humans effectively against avian influenza. It is only possible to produce a vaccine against a possible super-virus - in other words a combination of bird flu and conventional flu - when the virus actually exists. A normal flu vaccine does not protect against avian influenza. It is nevertheless wise to have a vaccination because this reduces the risk of a new super-virus that can be transmitted from human to human developing. You will also be able to rule out a conventional flu if you suffer symptoms such as high fever or breathing complaints.

What good is a conventional flu vaccination?
The flu vaccine adapted to the current season does not protect you against the avian influenza virus. However, the vaccination can reduce the danger of a combination of both types of virus. Important: A flu vaccination only provides full protection after about two weeks.

Can I still eat poultry meat, eggs and other poultry products? What about raw eggs? Is there a risk of transmission here? Is there anything special consumers have to remember when buying food?
Firstly it must be said that German domestic poultry flocks are free of fowl plague and that the measures that have been implemented were taken as a precaution to minimize the risk of the virus spreading from wild birds to domestic poultry. This means that food like poultry can be bought and eaten without restriction if normal hygiene measures are taken. The virus can be transmitted through raw eggs if the animals are infected. At the same time it should be said that an infection with H5N1 drastically reduces egg production by birds and results in substantial deaths, which means that the marketing possibilities of farms concerned are very limited. In addition to this, farms with suspected or confirmed outbreaks are subject to a strict quarantine so that no eggs from them may be passed on to consumers.

The avian influenza viruses die off at a temperature of 70°C. Hence if you cook or fry poultry meat and products before eating, it is safe to continue eating them according to current knowledge. You should follow general hygiene rules when preparing the food.

Should I be frightened of the pigeons in the park?
Pigeons are not very susceptible to the avian influenza virus. If they do become infected, they only excrete the virus in very low quantities. The experts of the Bavarian State Ministry of Consumer Protection therefore do not regard pigeons as animals of risk. Nevertheless: Do not feed pigeons or any other birds such as swans and ducks.

Are the droppings of infected animals dangerous?
According to Jochen Hentschke, vet and head of the Center for Infection Diagnostics at the Institute for Food, Drugs and Animal Epidemics in Berlin, the droppings of diseased birds do contain the virus. Albeit usually in very small quantities. The flu virus also does not survive long in the droppings. In sunshine it dies off after a few hours. In overcast weather this takes at least 24 hours.

If you want to clean your car of bird droppings, you should, purely as a precaution, wear gloves and use lots of water and a cloth that you can throw away at the end and not place back in a kitchen cupboard or the like. If you touch bird droppings, you should wash your hands. That suffices. Due to the small quantity involved, droppings underneath your shoes are not dangerous.

How can I identify avian influenza in birds?
According to experts, diseased birds look apathetic and suffer from breathing difficulties. They sway a lot and their feathers are ruffled.

Classical fowl plague cannot be identified by the symptoms alone. It is very similar to, for example, atypical fowl plague, also known as Newcastle disease. The results of poisoning are often also very similar.

Diagnosis: When looking for the virus, laboratories first confirm whether samples from, for example, dead birds contain the genetic material of flu viruses. If so, they determine by molecular biological methods whether the viruses are of one of the avian influenza subtypes H5 or H7. If this question is also answered with yes, they still have to test whether the virus belongs to one of the aggressive subtypes. Finally the experts analyze the N-protein (neuraminidase) on the surface of the virus. Only then do they know whether the bird examined is infected with the dangerous H5N1 virus or another subtype.

What should I do if I find a dead bird?
"Do not touch it," says Hiltrud Schrandt of the State Agency for Consumer Protection and Food Safety of Lower Saxony.

You should report the whereabouts of dead birds to the local police or municipal authorities, who will then call in the veterinary agencies. The animals are then transported to a laboratory in special containers for examination.

Is there a danger for pets?
Pet birds should not come into contact with wild birds. Outdoor aviaries must be protected appropriately.
An animal that is kept indoors cannot become infected. It is also not in danger if it is allowed to fly on the balcony. Even if an infected swan was to fly past and drop feces on the railings of the balcony just at the right moment, the quantity would hardly be enough for an infection.

Experts regard the risk of infection for dogs and cats as small. However, there are cases of transmission of the virus from poultry to mammals, says the bird expert Wolfgang Fiedler of the Max Planck Institute for Ornithology.
In many of these cases the animals evidently ate dead chickens. The owners of pets, for example dogs, should therefore "keep their animals under control as far as possible and ensure that they do not eat anything unchecked," says Fiedler.

According to Jochen Hentschke, vet and head of the Center for Infection Diagnostics at the Institute for Food, Drugs and Animal Epidemics in Berlin, however, the risk for dogs is at most theoretical. Not a single case of the virus infecting a dog is known to date. The situation with cats is different: "A cat can become infected by, for example, eating infected droppings or a dead bird. However, such an infection occurs very rarely because the quantity of virus would have to be very big. This is not usually the case with droppings. And which cats eat coots, ducks or swans?" says Hentschke.

Tigers and jaguars have become infected in zoos in Asia after being fed infected bird meat. The zoo in Cairo was closed because of avian influenza. Cats and dogs can continue to move around outdoors. Dogs should be kept on a leash in endangered areas.

What do poultry holders do to protect against infections?
According to Wilhelm Hoffrogge, president of the Association of the Poultry Industry in Lower Saxony, the poultry industry is generally subject to strict hygiene precautions to protect animal stocks against various pathogens. Protective suits are worn when entering sheds and workers first pass through a bath containing disinfectant. They also wear gloves.
If an outbreak of avian influenza is suspected, a respiratory protection mask with virus protection and tight-fitting protective goggles must also be worn in the sheds.

I still have questions on avian influenza - where can I find further information?
The German Federal Ministry of Agriculture has set up a hotline for citizens with questions on avian influenza. It can be reached Monday to Friday between 9:00 and 17:00 on the telephone numbers 01888-529-4601 or -4602, -4603, -4604, -4605, -4606, -4607, -4608 and -4609.

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