AVIAN INFLUENZA (BIRD FLU)
A
current influenza outbreak, formally called H5N1 after two distinctive
proteins on the flu virus, (but commonly referred to as bird or avian
flu), has so far mainly affected birds.
In
the last two decades the virus has appeared in China, Hong Kong, Japan,
Viet Nam, Thailand, Indonesia, Cambodia, Laos, Korea, Malaysia, Kazakhstan,
Mongolia and Russia, and most recently in Turkey and Romania. Four countries,
Thailand, Vietnam, Indonesia and Cambodia, have reported a total of
120 human cases of the H5N1 flu since 1997. Sixty people have died,
most after being sick for a few weeks. These people are thought to have
caught the disease by their contact with infected poultry. There has
been no known human to human transmission of the virus.
It
is possible that the H5N1 virus could mutate so that it can pass much
more easily from birds to humans and from there spread among humans.
If that were to happen, public health experts warn that the disease
could potentially spread to kill 100,000 to 1.7 million people in the
U.S., and 180 million to 360 million people world wide.
Other
strains of flu viruses that affect birds but not humans are also active.
A recent outbreak at a poultry farm in Gonzales County, Texas prompted
quarantine, the slaughter of more than 6,600 chickens and several international
bans on importation of U.S. poultry, including into Mexico. According
to the Centers for Disease Control, the strain found in Texas was not
the H5N1 strain, and is not believed to be infectious for humans. However,
it is highly contagious among certain kinds of birds and industry officials
are worried the Texas strain could spread and kill entire flocks of
chickens. The potential ramifications for U.S. insurers could be far-reaching
and involve a number of complex tort issues.
Even
if the H5N1 strain does not mutate to infect humans, the economic costs
associated with avian flu strains could easily be in the billions if
other countries, such as Mexico, impose bans on imported U.S. poultry
and U.S. consumers avoid buying domestic poultry. Still, the economic
costs are very different from the insurance costs. The following is
an overview of potential types of insurance coverages and the exposures
involved:
Potential Exposures If People Are Infected
Workers
Compensation: Workers involved in the handling of poultry could
be at risk. Because such an exposure is work-related, workers compensation
coverage would apply. In most states workers compensation coverage is
mandatory for all employers. However, farmers in some states under some
circumstances are exempt from workers compensation statutes.
Tort
Related Exposures: If the infected poultry were found to have
gotten into the food supply and people become ill as a result, litigation
could ensue. Although a non-infected plaintiff may seek compensation
for emotional distress from eating tainted poultry, fear of developing
a disease is not normally compensable.
Negligence: If people do contract the H5N1 virus, it could be an avenue for a tort
case, depending on the source of the infection. Eating meat from birds
infected with the virus is not dangerous because it is not a food-borne
illness and dies at high temperatures. But touching the birds may infect
humans. The argument could be made, if the tainted poultry reaches the
food supply, that the farmer, meat packer, processors, retailer/restaurant
etc., were all negligent and caused (or suffered) economic damage. In
that case, these parties would file suits against each other and against
outside parties.
Business
operation: Business might have difficulty operating in normal
patterns because a large percentage of employees might be unable or
unwilling to come to work for the duration of the outbreak and/or quarantine.
Parents of school age or younger children might want to (or be forced
to) stay home with them, particularly if day care facilities close.
Retail activity might shift strongly toward Internet- or phone-based
shopping. Travel related businesses might be severely affected.
Employee
benefits: If people do contract the H5N1 virus and some die
from it, experience-rated employer sponsored health insurance, short-term
disability income, and life insurance benefit plans could see greater
than anticipated claims levels and incur substantial rate increases,
at least temporarily. Retirement plans that provide death benefits would
also have unexpected payouts and might experience liquidity problems.
Personal
finance: If the disease hits families with children who have
insufficient life and/or health insurance, they could face severe financial
hardship.
How
are Pandemic, Avian and Seasonal Flu different?
Pandemic
Flu: Currently there is no pandemic flu. A flu pandemic is
a global outbreak that occurs when a new influenza A virus causes serious
human illness and spreads easily from person to person.
Avian
Flu: Bird flu is caused by avian influenza viruses, which occur
naturally among birds.
Seasonal
Flu: The flu is a contagious respiratory illness caused by
influenza viruses.
The U. S. Government plan addresses pandemic flu.
One
of the most important public health issues our Nation and the world
face is the threat of a global disease outbreak called a pandemic.
Preparedness
planning checklists for businesses & state/local governments are
now available.
Key Facts About Avian Influenza (Bird Flu) and Avian Influenza A (h5N1)
Virus
What
You Should Know About Avian Flu
This
fact sheet provides general information about avian influenza (bird
flu) and information about one type of bird flu, called avian influenza
A (H5N1), that has caused infections in birds in Asia and Europe and
in humans in Asia. .
Avian
Influenza (Bird Flu)
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 transmission has not been observed to continue beyond one person.
“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 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)
Avian
influenza A (H5N1) in Asia and Europe
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.
Outbreaks
of avian influenza H5N1 occurred among poultry in eight countries in
Asia (Cambodia, China, Indonesia, Japan, Laos, South Korea, Thailand,
and Vietnam) during late 2003 and early 2004. At that time, more than
100 million birds in the affected countries either died from the disease
or were killed in order to try to control the outbreaks.
By
March 2004, the outbreak was reported to be under control. Since late
June 2004, however, new outbreaks of influenza H5N1 among poultry were
reported by several countries in Asia (Cambodia, China [Tibet], Indonesia,
Kazakhstan, Malaysia, Mongolia, Russia [Siberia], Thailand, and Vietnam).
It is believed that these outbreaks are ongoing. Influenza H5N1 infection
also has been reported among poultry in Turkey and Romania and among
wild migratory birds in Croatia.
Human
cases of influenza A (H5N1) infection have been reported in Cambodia,
China, Indonesia, Thailand, and Vietnam. For the most current information
about avian influenza and cumulative case numbers, see the World Health
Organization (WHO) website at http://www.who.int/csr/disease/avian_influenza/en/.
Human
health risks during the H5N1 outbreak
H5N1
virus does not usually infect people, but more than 130 human cases
have been reported by the World Health Organization since January 2004.
Most of these cases have occurred as a result of people having direct
or close contact with infected poultry or contaminated surfaces; however,
a few cases of human-to-human spread of H5N1 have occurred.
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. In the current outbreaks in Asia
and Europe, more than half of those infected with the virus have died.
Most cases have occurred in previously healthy children and young adults.
However, it is possible that the only cases currently being reported
are those in the most severely ill people, and that the full range of
illness caused by the H5N1 virus has not yet been defined.
So
far, the spread of H5N1 virus from person to person has been rare and
has not continued beyond one person. Nonetheless, because all influenza
viruses have the ability to change, scientists are concerned that H5N1
virus one day could be able to infect humans and spread easily from
one person to another. Because these viruses do not commonly infect
humans, there is little or no immune protection against them in the
human population. If H5N1 virus were to gain the capacity to spread
easily from person to person, an influenza pandemic (worldwide outbreak
of disease) could begin. For more information about influenza pandemics,
see http://www.cdc.gov/flu/pandemic/
and http://www.pandemicflu.gov.
No
one can predict when a pandemic might occur. However, experts from around
the world are watching the H5N1 situation in Asia and Europe very closely
and are preparing for the possibility that the virus may begin to spread
more easily and widely from person to person.
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, oseltamavir and zanamavir,
would probably work to treat influenza caused by H5N1 virus, but additional
studies still need to be done to demonstrate their effectiveness.
There
currently is no commercially available vaccine to protect humans against
H5N1 virus that is being seen in Asia and Europe. However, vaccine development
efforts are taking place. Research studies to test a vaccine to protect
humans against H5N1 virus began in April 2005, and a series of clinical
trials is under way. For more information about H5N1 vaccine development
process, visit the National Institutes of Health website.
Questions and Answers About Avian Influenza
(Bird Flu) and Avian Influenza A (H5N1) Virus
Avian
Influenza
What
is avian influenza (bird flu)?
Avian
influenza is an infection caused by avian (bird) influenza (flu) viruses.
These flu 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.
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.
How
does avian influenza spread among birds?
Infected
birds shed influenza virus in their saliva, nasal secretions, and feces.
Susceptible birds become infected when they have contact with contaminated
excretions or with surfaces that are contaminated with excretions or
secretions. 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.
Do
avian influenza viruses infect humans?
Bird
flu viruses do not usually infect humans, but more than 100 confirmed
cases of human infection with bird flu viruses have occurred since 1997.
The World Health Organization (WHO) maintains situation updates and
cumulative reports of human cases of avian influenza A (H5N1). Please
visit these and previous WHO situation updates and cumulative reports
for additional information.
How
do people become infected with avian influenza viruses?
Most
cases of avian influenza infection in humans have resulted from direct
or close contact with infected poultry (e.g., domesticated chicken,
ducks, and turkeys) or surfaces contaminated with secretions and excretions
from infected birds. The spread of avian influenza viruses from an ill
person to another person has been reported very rarely, and transmission
has not been observed to continue beyond one person. During an outbreak
of avian influenza among poultry, there is a possible risk to people
who have direct or close contact with infected birds or with surfaces
that have been contaminated with secretions and excretions from infected
birds.
What
are the symptoms of avian influenza in humans?
Symptoms
of avian influenza in humans have ranged from typical human influenza-like
symptoms (fever, cough, sore throat, and muscle aches) to eye infections,
pneumonia, severe respiratory diseases (such as acute respiratory distress
syndrome), and other severe and life-threatening complications. The
symptoms of avian influenza may depend on which specific virus subtype
and strain caused the infection.
How
is avian influenza detected in humans?
A
laboratory test is needed to confirm avian influenza in humans.
What
are the implications of avian influenza to human health?
Two
main risks for human health from avian influenza are
- the
risk of direct infection when the virus passes from the infected bird
to humans, sometimes resulting in severe disease; and
- the risk that the virus “if given enough opportunities”
will change into a form that is highly infectious for humans and spreads
easily from person to person.
How
Is Avian Influenza In Humans Treated?
H5N1
VaccinesCurrently no vaccine is available to protect humans against
the H5N1 virus that is being seen in Asia. However, vaccine development
efforts are under way. Research studies to test a vaccine to protect
humans against H5N1 virus began in April 2005. (Researchers are also
working on a vaccine against H9N2, another bird flu virus subtype.)
Studies
done in laboratories suggest that the prescription medicines approved
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 determine the effectiveness of these medicines.
Does
the current seasonal influenza vaccine protect me from avian influenza?
No.
Influenza vaccine for the 2005-06 season does not provide protection
against avian influenza.
Should
I wear a surgical mask to prevent exposure to avian influenza?
Currently,
wearing a mask is not recommended for routine use (e.g., in public)
for preventing influenza exposure. In the United States, disposable
surgical and procedure masks have been widely used in health-care settings
to prevent exposure to respiratory infections, but the masks have not
been used commonly in community settings, such as schools, businesses,
and public gatherings.
Is
there a risk for becoming infected with avian influenza by eating poultry?
There
is no evidence that properly cooked poultry or eggs can be a source
of infection for avian influenza viruses. For more information about
avian influenza and food safety issues, visit the World Health Organization
website .
The
U.S. government carefully controls domestic and imported food products,
and in 2004 issued a ban on importation of poultry from countries affected
by avian influenza viruses, including the H5N1 strain. This ban still
is in place. For more information, see Embargo of Birds, http://www.cdc.gov/flu/avian/outbreaks/embargo.htm .
We
have a small flock of chickens. Is it safe to keep them?
Yes.
In the United States there is no need at present to remove a flock of
chickens because of concerns regarding avian influenza. The U.S. Department
of Agriculture monitors potential infection of poultry and poultry products
by avian influenza viruses and other infectious disease agents.
Avian Influenza A (H5N1)
What
is the avian influenza A (H5N1) virus that has been reported in Asia
and Europe?
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.
Outbreaks
of avian influenza H5N1 occurred among poultry in eight countries in
Asia (Cambodia , China, Indonesia, Japan, Laos, South Korea, Thailand,
and Vietnam) during late 2003 and early 2004. At that time, more than
100 million birds in the affected countries either died from the disease
or were killed in order to try to control the outbreaks. By March 2004,
the outbreak was reported to be under control.
Since
late June 2004, however, new outbreaks of influenza H5N1 among poultry
have been reported by several countries in Asia (Cambodia, China [Tibet],
Indonesia, Kazakhstan, Malaysia, Mongolia, Russia [Siberia], Thailand,
and Vietnam). It is believed that these outbreaks are ongoing. Influenza
H5N1 infection also has been reported among poultry in Turkey and Romania
and among wild migratory birds in Croatia .
Human
cases of influenza A (H5N1) infection have been reported in Cambodia,
China, Indonesia, Thailand, and Vietnam. For the most current information
about avian influenza and cumulative case numbers, see the World Health
Organization website at http://www.who.int/csr/disease/avian_influenza/en/ .
What
are the risks to humans from the current H5N1 outbreak in Asia and Europe?
H5N1
virus does not usually infect people, but more than 100 human cases
have been reported. Most of these cases have occurred from direct or
close contact with infected poultry or contaminated surfaces; however,
a few cases of human-to-human spread of H5N1 virus have occurred.
So
far, spread of H5N1 virus from person to person has been rare and has
not continued beyond one person. Nonetheless, because all influenza
viruses have the ability to change, scientists are concerned that H5N1
virus one day could be able to infect humans and spread easily from
one person to another. Because these viruses do not commonly infect
humans, there is little or no immune protection against them in the
human population.
If
H5N1 virus were to gain the capacity to spread easily from person to
person, an influenza pandemic (worldwide outbreak of disease) could
begin. No one can predict when a pandemic might occur. However, experts
from around the world are watching the H5N1 situation in Asia and Europe
very closely and are preparing for the possibility that the virus may
begin to spread more easily from person to person.
How
does H5N1 virus differ from seasonal influenza viruses that infect humans?
Of
the few avian influenza viruses that have crossed the species barrier
to infect humans, H5N1 virus has caused the largest number of reported
cases of severe disease and death in humans. In the current situation
in Asia , more than half of the people infected with the virus have
died. Most cases have occurred in previously healthy children and young
adults. However, it is possible that the only cases currently being
reported are those in the most severely ill people and that the full
range of illness caused by the H5N1 virus has not yet been defined.
Unlike
seasonal influenza, in which infection usually causes only mild respiratory
symptoms in most people, H5N1 infection may follow an unusually aggressive
clinical course, with rapid deterioration and high fatality. Primary
viral pneumonia and multi-organ failure have been common among people
who have become ill with H5N1 influenza.
How
is infection with H5N1 virus in humans treated?
Most
H5N1 viruses that have caused human illness and death appear to be resistant
to amantadine and rimantadine, two antiviral medications commonly used
for treatment of patients with influenza. Two other antiviral medications,
oseltamivir and zanamavir, would probably work to treat influenza caused
by H5N1 virus, but additional studies are needed to demonstrate their
current and ongoing effectiveness.
Is
there a vaccine to protect humans from H5N1 virus?
There
currently is no commercially available vaccine to protect humans against
the H5N1 virus that is being detected in Asia and Europe. However, vaccine
development efforts are taking place. Research studies to test a vaccine
that will protect humans against H5N1 virus began in April 2005, and
a series of clinical trials is under way. For more information about
the H5N1 vaccine development process, visit the National Institutes
of Health website .
What
does CDC recommend regarding H5N1 virus?
In
February 2004, CDC provided U.S. public health departments with recommendations
for enhanced surveillance (?detection?) of H5N1 influenza in the country.
Follow-up messages, distributed via the Health Alert Network, were sent
to the health departments on August 12, 2004, and February 4, 2005;
both alerts reminded public health departments about recommendations
for detecting (domestic surveillance), diagnosing, and preventing the
spread of H5N1 virus. The alerts also recommended measures for laboratory
testing for H5N1 virus. To read the alerts, visit Health Updates on
Avian Influenza .
Does
CDC recommend travel restrictions to areas with known H5N1 outbreaks?
CDC
does not recommend any travel restrictions to affected countries at
this time. However, CDC currently advises that travelers to countries
with known outbreaks of H5N1 influenza avoid poultry farms, contact
with animals in live food markets, and any surfaces that appear to be
contaminated with feces from poultry or other animals. For more information,
visit Travelers' Health .
Influenza Pandemic Preparedness
What
changes are needed for H5N1 or another avian influenza virus to cause
a pandemic?
Three
conditions must be met for a pandemic to start: 1) a new influenza virus
subtype must emerge; 2) it must infect humans and causes serious illness;
and 3) it must spread easily and sustainedly (continue without interruption)
among humans. The H5N1 virus in Asia and Europe meets the first two
conditions: it is a new virus for humans (H5N1 viruses have never circulated
widely among people), and it has infected more than 100 humans, killing
over half of them.
However,
the third condition, the establishment of efficient and sustained human-to-human
transmission of the virus, has not occurred. For this to take place,
the H5N1 virus would need to improve its transmissibility among humans.
This could occur either by “reassortment” or adaptive mutation.
Reassortment
occurs when genetic material is exchanged between human and avian viruses
during co-infection (infection with both viruses at the same time) of
a human or pig. The result could be a fully transmissible pandemic virus‹that
is, a virus that can spread easily and directly to humans. A more gradual
process is adaptive mutation, where the capability of a virus to bind
to human cells increases during infections of humans.
What
is CDC doing to prepare for a possible H5N1 influenza pandemic?
CDC
is taking part in a number of pandemic prevention and preparedness activities,
including the following:
- Providing
leadership to the National Pandemic Influenza Preparedness and Response
Task Force, created in May 2005 by the Secretary of the U.S. Department
of Health and Human Services.
- Working
with the Association of Public Health Laboratories on training workshops
for state laboratories on the use of special laboratory (molecular)
techniques to identify H5 viruses.
- Working
with the Council of State and Territorial Epidemiologists and others
to help states with their pandemic planning efforts.
- Working
with other agencies, such as the Department of Defense and the Veterans
Administration, on antiviral stockpile issues.
- Working
with the World Health Organization (WHO) to investigate influenza
H5N1 among people (e.g., in Vietnam) and to provide help in laboratory
diagnostics and training to local authorities.
- Performing
laboratory testing of H5N1 viruses.
- Starting
a $5.5 million initiative to improve influenza surveillance in Asia.
- Holding
or taking part in training sessions to improve local capacities to
conduct surveillance for possible human cases of H5N1 and to detect
influenza A H5 viruses by using laboratory techniques.
- Developing
and distributing reagent kits to detect the currently circulating
influenza A H5N1 viruses.
CDC
also is working closely with WHO and the National Institutes of Health
on safety testing of vaccine candidates and development of additional
vaccine virus seed candidates for influenza A (H5N1) and other subtypes
of influenza A viruses.
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