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Questions and Answers About Avian Influenza (Bird Flu)
and Avian Influenza A (H5N1) Virus
Avian Influenza
How is avian influenza detected
in humans?
Avian influenza cannot be diagnosed by symptoms alone,
so a laboratory test is required. Avian influenza is usually
diagnosed by collecting a swab from the nose or throat during
the first few days of illness. This swab is then sent to a
laboratory, where they will either look for avian influenza
virus using a molecular test, or they will try to grow the
virus. Growing avian influenza viruses should only be done
in laboratories with high levels of protection. If it is late
in the illness, it may be difficult to find an avian influenza
virus directly using these methods. If this is the case, it
may still be possible to diagnose avian influenza by looking
for evidence of the body's response to the virus. This is not
always an option because it requires two blood specimens (one
taken during the first few days of illness and another taken
some weeks later), and it can take several weeks to verify
the results.
What are the implications of avian influenza to
human health?
Two main risks for human health from avian influenza
are 1) the risk of direct infection when the virus passes
from the infected bird to humans, sometimes resulting in
severe disease; and 2) 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?
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 seasonal influenza vaccine protect against
avian influenza infection in people?
No. Seasonal influenza vaccine 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.
Can I get avian influenza from eating or preparing
poultry or eggs?
You cannot get avian influenza from properly handled and
cooked poultry and eggs.
There currently is no scientific evidence that people have
been infected with bird flu by eating safely handled and
properly cooked poultry or eggs.
Most cases of avian influenza infection in humans have resulted
from direct or close contact with infected poultry or surfaces
contaminated with secretions and excretions from infected
birds. Even if poultry and eggs were to be contaminated with
the virus, proper cooking would kill it. In fact, recent
studies have shown that the cooking methods that are already
recommended by the U.S. Department of Agriculture (USDA)
and the Food and Drug Administration (FDA) for poultry and
eggs to prevent other infections will destroy influenza viruses
as well.
So to stay safe, the advice is the same for protecting against
any infection from poultry:
- Wash your hands with soap and warm water for at least
20 seconds before and after handling raw poultry and eggs.
- Clean cutting boards and other utensils with soap and
hot water to keep raw poultry from contaminating other
foods.
- Use a food thermometer to make sure you cook poultry
to a temperature of at least 165 degrees Fahrenheit Consumers
may wish to cook poultry to a higher temperature for personal
preference.
- Cook eggs until whites and yolks are firm.
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.
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.
For additional information about avian influenza visit pandemicflu.gov.
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 for which there
is little or no human immunity; 2) it must infect humans and
causes illness; and 3) it must spread easily and sustainably
(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 190 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 another mammal.
The result could be a fully transmissible pandemic virus—that
is, a virus that can spread easily and directly between 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 has developed and is distributing the first FDA approved
test for the detection of the H5 viruses that first emerged
in Asia in 2003.
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.
To read the rest of this article (including information
about importing pet birds, and cats and dogs and avian flu)
from the CDC, please click here: http://www.cdc.gov/flu/avian/gen-info/qa.htm
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