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Avian flu (bird flu)Published by BUPA's health information team, healthinfo@bupa.com, February 2006. This factsheet is for people who would like more information about avian (bird) flu. Avian flu (also known as bird flu) is a form of influenza that affects birds. A number of countries have been affected by bird flu infecting their poultry stocks, particularly in Asia. In some of these countries, a small number of people have caught the bird flu virus from being in close contact with infected chickens. Scientists fear that the bird flu virus could merge with a human flu virus. This might result in a new, fatal flu virus that could be passed rapidly from person to person, triggering the next human flu pandemic with potentially devastating results.
What is bird flu?"Avian" refers to birds and 'flu' is the common name for influenza. There are three different groups of influenza virus which vary in their severity and ability to cause an epidemic or a pandemic. An epidemic is a widespread disease that affects many individuals in a population. A pandemic is an epidemic that strikes a very wide area, usually world-wide.
Bird flu is caused by the type A virus. Influenza AThere are a number of different strains (types) of influenza A virus. The types are based on two proteins on the surface of the virus. The H subtypes are important as they determine how well the virus will bind to and enter cells, where multiplication of the virus then occurs. The N subtypes determine the release of newly formed virus from the cells. There are 16 H subtypes and nine N subtypes. Not all of them are life threatening to birds, but the H5N1 type is highly pathogenic (disease-causing). H5N1H5N1 produces a severe disease in birds - almost all of infected poultry in Asia has died as a result of the virus. Bird flu doesn't just affect domestic poultry - it also affects wild birds, including migratory birds such as wild ducks and geese. It can also affect pigs, although this is less common. How do people get bird flu?The bird flu virus can occasionally jump between species and infect people who have been in close contact with infected birds, such as poultry workers. When a bird is infected with bird flu, it sheds the flu virus in its faeces, saliva and mucus. Other birds become infected by inhaling or eating the virus. The virus can also infect people if they inhale dried faeces that have become trampled into dust or stuck to the feathers or other parts of the body of the infected bird. Given the small numbers of cases of bird flu in people in relation to the huge number of birds affected, it doesn't seem that the virus is easily transmitted from bird to human. Can you get bird flu from eating poultry or eggs?There is no evidence to suggest that you can catch bird flu from eating poultry or eggs. The European Food Safety Authority has advised that there should be no change to longstanding food safety advice that poultry products should be properly cooked to protect against possible risks of food poisoning from other causes. Whilst it is unlikely that the virus could be passed to you from eating raw meat or eggs, cooking food properly will destroy the bird flu virus and eliminate this potential risk. Can bird flu be passed from person to person?There are signs that bird flu might have been passed between a few people, but it isn't spreading easily between humans. There have been a number of cases where a person with bird flu has infected a close family member. It seems that bird flu is only passed between people if they are in very close contact with each other. However, it is difficult to tell if human-to-human transmission has occurred since the family members are exposed to the same animal and environmental sources as well as to one another. The concern is that the H5N1 virus will either:
Symptoms of bird fluThe initial symptoms of bird flu are very similar to other types of flu and include:
It usually takes three to seven days for bird flu symptoms to develop. More severe infections can lead to life threatening complications including:
It is not yet understood why some people recover fully and others die. Diagnosis of bird fluIn the UK there have been no reports of human exposure to bird flu. It is extremely unlikely unless you have been exposed to infected poultry or wild birds in countries that have outbreaks of bird flu. If you have been in contact with infected poultry or birds, and are concerned about bird flu, you should visit your GP. Your doctor will examine you and ask you about your symptoms. He or she will need to know which countries or regions you have recently visited and if you have been exposed to dead or unwell birds. Your doctor may take a swab from your nose and throat. These samples will be sent to a laboratory to be examined. Treatment of bird fluIt is possible that antiviral drugs used to treat other types of flu may be effective in treating bird flu in humans. The following antiviral drugs can reduce the severity of ordinary flu:
It is hoped that if administered early (within two days) these drugs will improve the chances of people who get bird flu. There is evidence to suggest that the H5N1 bird flu virus responds to oseltamivir. This has led experts to suggest that it may also work against a pandemic strain. However, there are also reports of partial resistance to oseltamivir by some flu viruses and tests are ongoing. Vaccines for bird flu and pandemic fluThere is currently no vaccine to prevent bird flu in humans. Scientists are working on developing a vaccine, but it is difficult because the virus frequently changes. A vaccine against pandemic flu will need to closely match the pandemic virus so large-scale commercial production cannot start until the new human virus has emerged and a pandemic has been declared. As soon as a pandemic strain of flu emerges, scientists will work on isolating the virus and begin to develop a vaccine but this would not be available for some time. Will the annual flu vaccine protect me against avian flu?Currently available vaccines will not protect you against bird flu as they are not effective against the H5N1 strain of the virus. Although existing vaccines do not work against the bird flu H5N1 virus, they are being used to prevent poultry workers in affected countries from getting ordinary human flu. This reduces the risk that someone might catch human and bird flu at the same time, which would give the viruses the opportunity to merge and create a new virus capable of causing a pandemic. Prevention of bird fluIt is possible that bird flu could spread across countries by:
Countries around the world are taking a number of measures to prevent the spread of bird flu. These are explained below. Eradicating bird fluIn the countries that have been affected by avian bird flu, there are measures to contain the virus by culling affected poultry stocks. By removing the potential for the virus to spread through the countries' bird populations, it is hoped that the virus will be contained and removed from circulation. Banning importsThe European Union has banned imports of poultry from countries that are affected by bird flu outbreaks. It has also banned the import of captive live birds from any country that is not a member of the European Community. Advice for travellers to affected countriesThe advice for travellers to affected countries is to:
Further information
Sources
Related topicsThis information was published by BUPA's health information team and is based on reputable sources of medical evidence. It has been peer reviewed by Dr James Quekett, Bsc.MB Ch.B MRCGP DRCOG DFFP. partner/principal general practitioner at Rowcroft Medical Centre, and by BUPA doctors. The content is intended for general information only and does not replace the need for personal advice from a qualified health professional.
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