Monday 2nd November, 2009
How did the current outbreak start?
The outbreak of avian influenza of most concern - H5N1 - began in poultry in South Korea in mid-December 2003, and has affected birds in many countries in Asia, Europe, Middle East and Africa. It involves a variant of the same virus subtype as that associated with the 1997 Hong Kong outbreak.
WHAT IS BIRD FLU?
Avian influenza or 'bird flu' is a contagious disease of birds, caused by influenza A viruses that can cause a range of symptoms, from mild illness and low mortality to a highly contagious disease with a near 100% fatality rate. The bird flu virus currently affecting poultry and some people in Asia and other areas is the highly pathogenic H5N1 strain of the virus.
How is it spread?
As the virus can remain viable in contaminated droppings for long periods, it can be spread among birds, and from birds to other animals, through ingestion or inhalation. All bird species are thought to be susceptible to avian influenza. Migratory birds such as wild ducks and geese can carry the viruses, often without any symptoms, and show the greatest resistance to infection. Domestic poultry flocks, however, are particularly vulnerable to epidemics of a rapid, severe and fatal form of the disease.
How is it spread?
As the virus can remain viable in contaminated droppings for long periods, it can be spread among birds, and from birds to other animals, through ingestion or inhalation. All bird species are thought to be susceptible to avian influenza. Migratory birds such as wild ducks and geese can carry the viruses, often without any symptoms, and show the greatest resistance to infection. Domestic poultry flocks, however, are particularly vulnerable to epidemics of a rapid, severe and fatal form of the disease.
What kind of virus is it?
There are many different subtypes of influenza A virus. The most virulent are called highly pathogenic avian influenza and can reach epidemic levels among birds. Of these, subtype H5, and more particularly subtype H5N1, pose the greatest concern for human health. According to the World Health Organization (WHO), there is mounting evidence that the H5N1 strain has a unique capacity to jump the species barrier and cause severe disease, with high mortality, in people.
There are many different subtypes of influenza A virus. The most virulent are called highly pathogenic avian influenza and can reach epidemic levels among birds. Of these, subtype H5, and more particularly subtype H5N1, pose the greatest concern for human health. According to the World Health Organization (WHO), there is mounting evidence that the H5N1 strain has a unique capacity to jump the species barrier and cause severe disease, with high mortality, in people.
How did the current outbreak start?
The outbreak of avian influenza of most concern - H5N1 - began in poultry in South Korea in mid-December 2003, and has affected birds in many countries in Asia, Europe, Middle East and Africa. It involves a variant of the same virus subtype as that associated with the 1997 Hong Kong outbreak.
How can bird flu infect people?
H5N1 is able to infect people although it does not do this easily. In human populations, where domestic pigs and wild and domestic birds live in close proximity with people, the mingling and exchange of human and animal viruses can more easily occur. Those who have become infected have had close direct contact with infected birds.
H5N1 is able to infect people although it does not do this easily. In human populations, where domestic pigs and wild and domestic birds live in close proximity with people, the mingling and exchange of human and animal viruses can more easily occur. Those who have become infected have had close direct contact with infected birds.
What symptoms does it cause?
Human infection with avian influenza viruses usually causes conjunctivitis (eye infection) and mild flu-like symptoms, with one notable exception, the highly pathogenic H5N1 virus which can be deadly. The first documented cases in people appeared in Hong Kong in 1997, when 18 people infected with an H5N1 virus strain were admitted to hospital, six of whom died. As of 15 November 2006, 258 reported cases of H5N1 infection in people have occurred in ten countries, Thailand, Vietnam, Cambodia, Indonesia, China, Turkey, Iraq, Azerbaijan, Egypt, and Djibouti. One hundred and fifty-three of these have been fatal.
Human infection with avian influenza viruses usually causes conjunctivitis (eye infection) and mild flu-like symptoms, with one notable exception, the highly pathogenic H5N1 virus which can be deadly. The first documented cases in people appeared in Hong Kong in 1997, when 18 people infected with an H5N1 virus strain were admitted to hospital, six of whom died. As of 15 November 2006, 258 reported cases of H5N1 infection in people have occurred in ten countries, Thailand, Vietnam, Cambodia, Indonesia, China, Turkey, Iraq, Azerbaijan, Egypt, and Djibouti. One hundred and fifty-three of these have been fatal.
Risk of a human influenza pandemic
"We do not know what the virus is that will cause pandemic 'flu. What we do know is that Mother Nature has the recipe book and its just a matter of time before she starts cooking,." said Sir Liam Donaldson, Chief Medical Officer. "Wherever in the world a flu pandemic starts, perhaps with its epicentre in the Far East, we must assume we will be unable to prevent it reaching the UK. When it does, its impact will be severe in the number of illnesses and the disruption to everyday life."
"We do not know what the virus is that will cause pandemic 'flu. What we do know is that Mother Nature has the recipe book and its just a matter of time before she starts cooking,." said Sir Liam Donaldson, Chief Medical Officer. "Wherever in the world a flu pandemic starts, perhaps with its epicentre in the Far East, we must assume we will be unable to prevent it reaching the UK. When it does, its impact will be severe in the number of illnesses and the disruption to everyday life."
What is a pandemic, and what causes it?
We are used to epidemics of 'ordinary' flu, which occur seasonally, every year, around the world. An epidemic is a widespread outbreak of disease occurring in a single community, population or region. A pandemic, on the other hand, occurs on a much greater scale, spreading around the world and affecting many hundreds of thousands of people across many countries.
Three influenza pandemics occurred in the last century - 1918 to 1919 (Spanish flu), 1957 to 1958 (Asian flu) and 1968 to 1969 (Hong Kong flu). All affected large numbers of the population, causing many deaths and huge economic and social disruption. In the case of the 1918 outbreak, around 50 million people are thought to have died.
We are used to epidemics of 'ordinary' flu, which occur seasonally, every year, around the world. An epidemic is a widespread outbreak of disease occurring in a single community, population or region. A pandemic, on the other hand, occurs on a much greater scale, spreading around the world and affecting many hundreds of thousands of people across many countries.
Three influenza pandemics occurred in the last century - 1918 to 1919 (Spanish flu), 1957 to 1958 (Asian flu) and 1968 to 1969 (Hong Kong flu). All affected large numbers of the population, causing many deaths and huge economic and social disruption. In the case of the 1918 outbreak, around 50 million people are thought to have died.
No comments:
Post a Comment