عذبة المشاعر
11-15-2006, 06:44 PM
What is bird flu?
Like humans and other species, birds are susceptible to flu.
There are 15 types of bird, or avian, flu.
The most contagious strains, which are usually fatal in birds, are H5 and H7.
The type currently causing concern is the deadly strain H5N1, which can prove fatal to humans.
Migratory wildfowl, notably wild ducks, are natural carriers of the viruses, but are unlikely to actually develop an infection.
The risk is that they pass it on to domestic birds, who are much more suscpetible to the virus.
Q: How do humans catch bird flu?
Bird flu was thought only to infect birds until the first human cases were seen in Hong Kong in 1997.
Humans catch the disease through close contact with live infected birds.
Birds excrete the virus in their faeces, which dry and become pulverised, and are then inhaled.
Symptoms are similar to other types of flu - fever, malaise, sore throats and coughs. People can also develop conjunctivitis.
Researchers are now concerned because scientists studying a case in Vietnam found the virus can affect all parts of the body, not just the lungs.
This could mean that many illnesses, and even deaths, thought to have been caused by something else, may have been due to the bird flu virus.
Q: Is it possible to stop bird flu coming into a country?
Because it is carried by birds, there is no way of preventing its spread.
But that does not mean it will be passed to domestic flocks. Experts say proper poultry controls - such as preventing wild birds getting in to poultry houses - which are present in the UK, should prevent that happening.
In addition, they say monitoring of the migratory patterns of wild birds should provide early alerts of the arrival of infected flocks - meaning they could be targeted on arrival.
Q: How many people have been affected?
As of 9 January, 2006, the World Health Organisation had confirmed 146 cases of H5N1 in humans in Indonesia, Vietnam, Thailand, Cambodia, China and Turkey, leading to 76 deaths.
Click here to find the latest information from the WHO on the numbers infected and killed by avian flu.
Q: Fourteen cases have been reported in Turkey since the start of this year. Why this sudden cluster?
The WHO has yet to confirm all these cases, but even if it does, there may well be a simple explanation.
For instance, increased media coverage means that individuals are more aware of the disease and are simply more willing to come forward and be tested.
There is also the possibility that the infection among domestic poultry had not been properly identified in Turkey.
But the most worrying explanation is that H5N1 has mutated into a form that can jump more easily between chickens and humans.
If this is the case then it also increases the chances of the virus mutating into a form that can pass easily between humans - as it is more likely to mix with human influenza viruses.
This is the real fear. Experts believe the virus could exchange genes with a human flu virus if a person was simultaneously infected with both.
The more this double infection happens, the higher the chance a new virus could be created and be passed from person to person, they say.
Concern has also been raised by research which showed that the virus which caused the 1918 pandemic was an avian flu virus.
Q: But it can't yet be passed from person to person?
For the most part, humans have contracted the virus following very close contact with sick birds.
There may have been examples of human-to-human transmission, but so far not in the form which could fuel a pandemic.
A case in Thailand indicated the probable transmission of the virus from a girl who had the disease to her mother, who also died.
The girl's aunt, who was also infected, survived the virus.
UK virology expert Professor John Oxford said these cases indicated the basic virus could be passed between humans, and predicted similar small clusters of cases would be seen again.
It is not the only instance where it has been thought bird flu has been passed between humans.
In 2004, two sisters died in Vietnam after possibly contracting bird flu from their brother who had died from an unidentified respiratory illness.
In a similar case in Hong Kong in 1997, a doctor possibly caught the disease from a patient with the H5N1 virus - but it was never conclusively proved.
Q: What would the consequences of a mass outbreak be?
Once the virus gained the ability to pass easily between humans the results could be catastrophic.
Worldwide, experts predict anything between two million and 50 million deaths.
However the mortality rate - which presently stands at around 50% of confirmed cases - could decline as it mutates, they say.
Q: Is there a vaccine?
There is not yet a definitive vaccine, but prototypes which offer protection against the H5N1 strain are being produced.
But antiviral drugs, such as Tamiflu which are already available and being stockpiled by countries such as the UK, may help limit symptoms and reduce the chances the disease will spread.
Concerns have been prompted by news that patients in Vietnam have become partially resistant to the Tamiflu, the drug that doctors plan to use to tackle a human bird flu outbreak.
Scientists say it may be helpful to have stocks of other drugs from the same family such as Relenza (zanamivir).
Q: Can I continue to eat chicken?
Yes. Experts say avian flu is not a food-borne virus, so eating chicken is safe.
The only people thought to be at risk are those involved in the slaughter and preparation of meat that may be infected.
However, the World Health Organisation recommends, to be absolutely safe all meat should be cooked to a temperature of at least 70C. Eggs should also be thoroughly cooked.
Professor Hugh Pennington of Aberdeen University underlined the negligible risk to consumers: "The virus is carried in the chicken's gut.
"A person would have to dry out the chicken meat and would have to sniff the carcass to be at any risk. But even then, it would be very hard to become infected."
Q: What is being done to contain the virus in the countries affected?
Millions of birds have been culled in an attempt to stop the spread of the disease among birds, which would in turn stop it being passed on to humans.
Like humans and other species, birds are susceptible to flu.
There are 15 types of bird, or avian, flu.
The most contagious strains, which are usually fatal in birds, are H5 and H7.
The type currently causing concern is the deadly strain H5N1, which can prove fatal to humans.
Migratory wildfowl, notably wild ducks, are natural carriers of the viruses, but are unlikely to actually develop an infection.
The risk is that they pass it on to domestic birds, who are much more suscpetible to the virus.
Q: How do humans catch bird flu?
Bird flu was thought only to infect birds until the first human cases were seen in Hong Kong in 1997.
Humans catch the disease through close contact with live infected birds.
Birds excrete the virus in their faeces, which dry and become pulverised, and are then inhaled.
Symptoms are similar to other types of flu - fever, malaise, sore throats and coughs. People can also develop conjunctivitis.
Researchers are now concerned because scientists studying a case in Vietnam found the virus can affect all parts of the body, not just the lungs.
This could mean that many illnesses, and even deaths, thought to have been caused by something else, may have been due to the bird flu virus.
Q: Is it possible to stop bird flu coming into a country?
Because it is carried by birds, there is no way of preventing its spread.
But that does not mean it will be passed to domestic flocks. Experts say proper poultry controls - such as preventing wild birds getting in to poultry houses - which are present in the UK, should prevent that happening.
In addition, they say monitoring of the migratory patterns of wild birds should provide early alerts of the arrival of infected flocks - meaning they could be targeted on arrival.
Q: How many people have been affected?
As of 9 January, 2006, the World Health Organisation had confirmed 146 cases of H5N1 in humans in Indonesia, Vietnam, Thailand, Cambodia, China and Turkey, leading to 76 deaths.
Click here to find the latest information from the WHO on the numbers infected and killed by avian flu.
Q: Fourteen cases have been reported in Turkey since the start of this year. Why this sudden cluster?
The WHO has yet to confirm all these cases, but even if it does, there may well be a simple explanation.
For instance, increased media coverage means that individuals are more aware of the disease and are simply more willing to come forward and be tested.
There is also the possibility that the infection among domestic poultry had not been properly identified in Turkey.
But the most worrying explanation is that H5N1 has mutated into a form that can jump more easily between chickens and humans.
If this is the case then it also increases the chances of the virus mutating into a form that can pass easily between humans - as it is more likely to mix with human influenza viruses.
This is the real fear. Experts believe the virus could exchange genes with a human flu virus if a person was simultaneously infected with both.
The more this double infection happens, the higher the chance a new virus could be created and be passed from person to person, they say.
Concern has also been raised by research which showed that the virus which caused the 1918 pandemic was an avian flu virus.
Q: But it can't yet be passed from person to person?
For the most part, humans have contracted the virus following very close contact with sick birds.
There may have been examples of human-to-human transmission, but so far not in the form which could fuel a pandemic.
A case in Thailand indicated the probable transmission of the virus from a girl who had the disease to her mother, who also died.
The girl's aunt, who was also infected, survived the virus.
UK virology expert Professor John Oxford said these cases indicated the basic virus could be passed between humans, and predicted similar small clusters of cases would be seen again.
It is not the only instance where it has been thought bird flu has been passed between humans.
In 2004, two sisters died in Vietnam after possibly contracting bird flu from their brother who had died from an unidentified respiratory illness.
In a similar case in Hong Kong in 1997, a doctor possibly caught the disease from a patient with the H5N1 virus - but it was never conclusively proved.
Q: What would the consequences of a mass outbreak be?
Once the virus gained the ability to pass easily between humans the results could be catastrophic.
Worldwide, experts predict anything between two million and 50 million deaths.
However the mortality rate - which presently stands at around 50% of confirmed cases - could decline as it mutates, they say.
Q: Is there a vaccine?
There is not yet a definitive vaccine, but prototypes which offer protection against the H5N1 strain are being produced.
But antiviral drugs, such as Tamiflu which are already available and being stockpiled by countries such as the UK, may help limit symptoms and reduce the chances the disease will spread.
Concerns have been prompted by news that patients in Vietnam have become partially resistant to the Tamiflu, the drug that doctors plan to use to tackle a human bird flu outbreak.
Scientists say it may be helpful to have stocks of other drugs from the same family such as Relenza (zanamivir).
Q: Can I continue to eat chicken?
Yes. Experts say avian flu is not a food-borne virus, so eating chicken is safe.
The only people thought to be at risk are those involved in the slaughter and preparation of meat that may be infected.
However, the World Health Organisation recommends, to be absolutely safe all meat should be cooked to a temperature of at least 70C. Eggs should also be thoroughly cooked.
Professor Hugh Pennington of Aberdeen University underlined the negligible risk to consumers: "The virus is carried in the chicken's gut.
"A person would have to dry out the chicken meat and would have to sniff the carcass to be at any risk. But even then, it would be very hard to become infected."
Q: What is being done to contain the virus in the countries affected?
Millions of birds have been culled in an attempt to stop the spread of the disease among birds, which would in turn stop it being passed on to humans.