Avian influenza ((H5N1) Bird Flu)
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| Avian influenza virus usually refers to influenza A viruses found chiefly in birds, but infections can occur in humans. The risk is generally low to most people, because the viruses do not usually infect humans. However, confirmed cases of human infection have been reported since 1997.… |
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other website or blog.
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Avian influenza in birds
Avian influenza is an infection caused by avian (bird) influenza (flu) viruses.
These influenza viruses occur naturally among birds. Wild birds worldwide carry
the viruses in their intestines, but usually do not get sick from them. However,
avian influenza is very contagious among birds and can make some
domesticated birds, including chickens, ducks, and turkeys, very sick and kill
them.
Infected birds shed influenza virus in their saliva, nasal secretions, and feces.
Susceptible birds become infected when they have contact with contaminated
secretions or excretions or with surfaces that are contaminated with secretions or
excretions from infected birds. Domesticated birds may become infected with
avian influenza virus through direct contact with infected waterfowl or other
infected poultry, or through contact with surfaces (such as dirt or cages) or
materials (such as water or feed) that have been contaminated with the virus.
Infection with avian influenza viruses in domestic poultry causes two main forms
of disease that are distinguished by low and high extremes of virulence. The “low
pathogenic” form may go undetected and usually causes only mild symptoms
(such as ruffled feathers and a drop in egg production). However, the highly
pathogenic form spreads more rapidly through flocks of poultry. This form may
cause disease that affects multiple internal organs and has a mortality rate that
can reach 90-100% often within 48 hours.
Human infection with avian influenza viruses
There are many different subtypes of type A influenza viruses. These subtypes
differ because of changes in certain proteins on the surface of the influenza A
virus (hemagglutinin [HA] and neuraminidase [NA] proteins). There are 16 known
HA subtypes and 9 known NA subtypes of influenza A viruses. Many different
combinations of HA and NA proteins are possible. Each combination represents a
different subtype. All known subtypes of influenza A viruses can be found in birds.
Usually, “avian influenza virus” refers to influenza A viruses found chiefly in birds,
but infections with these viruses can occur in humans. The risk from avian
influenza is generally low to most people, because the viruses do not usually
infect humans. However, confirmed cases of human infection from several
subtypes of avian influenza infection have been reported since 1997. Most cases
of avian influenza infection in humans have resulted from contact with infected
poultry (e.g., domesticated chicken, ducks, and turkeys) or surfaces
contaminated with secretion/excretions from infected birds. The spread of avian
influenza viruses from one ill person to another has been reported very rarely,
and has been limited, inefficient and unsustained.
“Human influenza virus” usually refers to those subtypes that spread widely
among humans. There are only three known A subtypes of influenza viruses
(H1N1, H1N2, and H3N2) currently circulating among humans. It is likely that
some genetic parts of current human influenza A viruses came from birds
originally. Influenza A viruses are constantly changing, and they might adapt over
time to infect and spread among humans.
During an outbreak of avian influenza among poultry, there is a possible risk to
people who have contact with infected birds or surfaces that have been
contaminated with secretions or excretions from infected birds.
Symptoms of avian influenza in humans have ranged from typical human
influenza-like symptoms (e.g., fever, cough, sore throat, and muscle aches) to
eye infections, pneumonia, severe respiratory diseases (such as acute
respiratory distress), and other severe and life-threatening complications. The
symptoms of avian influenza may depend on which virus caused the infection.
Studies done in laboratories suggest that some of the prescription medicines
approved in the United States for human influenza viruses should work in treating
avian influenza infection in humans. However, influenza viruses can become
resistant to these drugs, so these medications may not always work. Additional
studies are needed to demonstrate the effectiveness of these medicines.
Avian Influenza A (H5N1)
Influenza A (H5N1) virus – also called “H5N1 virus” – is an influenza A virus
subtype that occurs mainly in birds, is highly contagious among birds, and can be
deadly to them. H5N1 virus does not usually infect people, but infections with
these viruses have occurred in humans. Most of these cases have resulted from
people having direct or close contact with H5N1-infected poultry or H5N1-
contaminated surfaces.
Avian influenza A (H5N1) outbreaks
Outbreaks of highly pathogenic avian influenza A (H5N1) associated with illness
and death in humans have occurred in Asia since late 2003. In the United States,
different avian influenza viruses caused outbreaks among poultry in 2003 and
2004, and one human infection in 2003.
Human health risks during the H5N1 outbreak
Of the few avian influenza viruses that have crossed the species barrier to infect
humans, H5N1 has caused the largest number of detected cases of severe
disease and death in humans. However, it is possible that those cases in the
most severely ill people are more likely to be diagnosed and reported, while
milder cases go unreported. For the most current information about avian
influenza and cumulative case numbers, see the World Health Organization
(WHO) avian influenza website.
Of the human cases associated with the ongoing H5N1 outbreaks in poultry and
wild birds in Asia and parts of Europe, the Near East and Africa, more than half of
those people reported infected with the virus have died. Most cases have
occurred in previously healthy children and young adults and have resulted from
direct or close contact with H5N1-infected poultry or H5N1-contaminated
surfaces. In general, H5N1 remains a very rare disease in people. The H5N1
virus does not infect humans easily, and if a person is infected, it is very difficult
for the virus to spread to another person.
While there has been some human-to-human spread of H5N1, it has been
limited, inefficient and unsustained. For example, in 2004 in Thailand, probable
human-to-human spread in a family resulting from prolonged and very close
contact between an ill child and her mother was reported. In June 2006, WHO
reported evidence of human-to-human spread in Indonesia. In this situation, 8
people in one family were infected. The first family member is thought to have
become ill through contact with infected poultry. This person then infected six
family members. One of those six people (a child) then infected another family
member (his father). No further spread outside of the exposed family was
documented or suspected.
Treatment and vaccination for H5N1 virus in humans
The H5N1 virus that has caused human illness and death in Asia is resistant to
amantadine and rimantadine, two antiviral medications commonly used for
influenza. Two other antiviral medications, oseltamivir and zanamivir, would
probably work to treat influenza caused by H5N1 virus, but additional studies still
need to be done to demonstrate their effectiveness.
INFORMATION Adopted on March 24 2009 from CDC.GOV
Avian influenza is an infection caused by avian (bird) influenza (flu) viruses.
These influenza viruses occur naturally among birds. Wild birds worldwide carry
the viruses in their intestines, but usually do not get sick from them. However,
avian influenza is very contagious among birds and can make some
domesticated birds, including chickens, ducks, and turkeys, very sick and kill
them.
Infected birds shed influenza virus in their saliva, nasal secretions, and feces.
Susceptible birds become infected when they have contact with contaminated
secretions or excretions or with surfaces that are contaminated with secretions or
excretions from infected birds. Domesticated birds may become infected with
avian influenza virus through direct contact with infected waterfowl or other
infected poultry, or through contact with surfaces (such as dirt or cages) or
materials (such as water or feed) that have been contaminated with the virus.
Infection with avian influenza viruses in domestic poultry causes two main forms
of disease that are distinguished by low and high extremes of virulence. The “low
pathogenic” form may go undetected and usually causes only mild symptoms
(such as ruffled feathers and a drop in egg production). However, the highly
pathogenic form spreads more rapidly through flocks of poultry. This form may
cause disease that affects multiple internal organs and has a mortality rate that
can reach 90-100% often within 48 hours.
Human infection with avian influenza viruses
There are many different subtypes of type A influenza viruses. These subtypes
differ because of changes in certain proteins on the surface of the influenza A
virus (hemagglutinin [HA] and neuraminidase [NA] proteins). There are 16 known
HA subtypes and 9 known NA subtypes of influenza A viruses. Many different
combinations of HA and NA proteins are possible. Each combination represents a
different subtype. All known subtypes of influenza A viruses can be found in birds.
Usually, “avian influenza virus” refers to influenza A viruses found chiefly in birds,
but infections with these viruses can occur in humans. The risk from avian
influenza is generally low to most people, because the viruses do not usually
infect humans. However, confirmed cases of human infection from several
subtypes of avian influenza infection have been reported since 1997. Most cases
of avian influenza infection in humans have resulted from contact with infected
poultry (e.g., domesticated chicken, ducks, and turkeys) or surfaces
contaminated with secretion/excretions from infected birds. The spread of avian
influenza viruses from one ill person to another has been reported very rarely,
and has been limited, inefficient and unsustained.
“Human influenza virus” usually refers to those subtypes that spread widely
among humans. There are only three known A subtypes of influenza viruses
(H1N1, H1N2, and H3N2) currently circulating among humans. It is likely that
some genetic parts of current human influenza A viruses came from birds
originally. Influenza A viruses are constantly changing, and they might adapt over
time to infect and spread among humans.
During an outbreak of avian influenza among poultry, there is a possible risk to
people who have contact with infected birds or surfaces that have been
contaminated with secretions or excretions from infected birds.
Symptoms of avian influenza in humans have ranged from typical human
influenza-like symptoms (e.g., fever, cough, sore throat, and muscle aches) to
eye infections, pneumonia, severe respiratory diseases (such as acute
respiratory distress), and other severe and life-threatening complications. The
symptoms of avian influenza may depend on which virus caused the infection.
Studies done in laboratories suggest that some of the prescription medicines
approved in the United States for human influenza viruses should work in treating
avian influenza infection in humans. However, influenza viruses can become
resistant to these drugs, so these medications may not always work. Additional
studies are needed to demonstrate the effectiveness of these medicines.
Avian Influenza A (H5N1)
Influenza A (H5N1) virus – also called “H5N1 virus” – is an influenza A virus
subtype that occurs mainly in birds, is highly contagious among birds, and can be
deadly to them. H5N1 virus does not usually infect people, but infections with
these viruses have occurred in humans. Most of these cases have resulted from
people having direct or close contact with H5N1-infected poultry or H5N1-
contaminated surfaces.
Avian influenza A (H5N1) outbreaks
Outbreaks of highly pathogenic avian influenza A (H5N1) associated with illness
and death in humans have occurred in Asia since late 2003. In the United States,
different avian influenza viruses caused outbreaks among poultry in 2003 and
2004, and one human infection in 2003.
Human health risks during the H5N1 outbreak
Of the few avian influenza viruses that have crossed the species barrier to infect
humans, H5N1 has caused the largest number of detected cases of severe
disease and death in humans. However, it is possible that those cases in the
most severely ill people are more likely to be diagnosed and reported, while
milder cases go unreported. For the most current information about avian
influenza and cumulative case numbers, see the World Health Organization
(WHO) avian influenza website.
Of the human cases associated with the ongoing H5N1 outbreaks in poultry and
wild birds in Asia and parts of Europe, the Near East and Africa, more than half of
those people reported infected with the virus have died. Most cases have
occurred in previously healthy children and young adults and have resulted from
direct or close contact with H5N1-infected poultry or H5N1-contaminated
surfaces. In general, H5N1 remains a very rare disease in people. The H5N1
virus does not infect humans easily, and if a person is infected, it is very difficult
for the virus to spread to another person.
While there has been some human-to-human spread of H5N1, it has been
limited, inefficient and unsustained. For example, in 2004 in Thailand, probable
human-to-human spread in a family resulting from prolonged and very close
contact between an ill child and her mother was reported. In June 2006, WHO
reported evidence of human-to-human spread in Indonesia. In this situation, 8
people in one family were infected. The first family member is thought to have
become ill through contact with infected poultry. This person then infected six
family members. One of those six people (a child) then infected another family
member (his father). No further spread outside of the exposed family was
documented or suspected.
Treatment and vaccination for H5N1 virus in humans
The H5N1 virus that has caused human illness and death in Asia is resistant to
amantadine and rimantadine, two antiviral medications commonly used for
influenza. Two other antiviral medications, oseltamivir and zanamivir, would
probably work to treat influenza caused by H5N1 virus, but additional studies still
need to be done to demonstrate their effectiveness.
INFORMATION Adopted on March 24 2009 from CDC.GOV