You hear it over and
over, and we discussed this last year as
well, but good hand washing really is the
best prevention to catching flu and cold
viruses. Washing before you eat and after
a trip to the restroom is great, but this
time of year, the more frequently you wash
or sanitize your hands, the better. Handshakes,
doorknobs, drinking fountains- they're
all possible suspects.
Avian Influenza (also known as bird flu) has received a lot
of attention lately. Below we have provided some answers
to commonly asked questions about this subject, as presented
by the Department of Health and Human Services Centers for
Disease Control and Prevention.
What is avian influenza
Bird flu 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, bird flu
is very contagious among birds and can make some domesticated
birds, including chickens, ducks, and turkeys, very sick
and kill them.
Do bird flu viruses infect
Bird flu viruses do not usually infect humans, but several
cases of human infection with bird flu viruses have occurred
How are bird flu viruses different from human flu viruses?
There are many different subtypes of type A influenza viruses.
These subtypes differ because of certain proteins on the
surface of the influenza A virus (hemagglutinin [HA] and
neuraminidase [NA] proteins). There are 16 different HA subtypes
and 9 different NA subtypes of flu A viruses. Many different
combinations of HA and NA proteins are possible. Each combination
is a different subtype. All known subtypes of flu A viruses
can be found in birds. However, when we talk about “bird
flu” viruses, we are referring to influenza A subtypes
chiefly found in birds. They do not usually infect humans,
even though we know they can. When we talk about “human
flu viruses” we are referring to those subtypes that
occur widely in humans. There are only three known A subtypes
of human flu viruses (H1N1, H1N2, and H3N2); 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
What are the symptoms of
bird flu in humans?
Symptoms of bird flu in humans have ranged from typical flu-like
symptoms (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 bird flu may depend on which
virus caused the infection.
How does bird flu spread?
Infected birds shed flu virus in their saliva, nasal secretions,
and feces. Susceptible birds become infected when they have
contact with contaminated excretions or surfaces that are contaminated
with excretions. It is believed that most cases of bird flu
infection in humans have resulted from contact with infected
poultry or contaminated surfaces. 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.
How is bird flu in humans
Studies done in laboratories suggest that the prescription
medicines approved for human flu viruses should work in preventing
bird flu infection in humans. However, flu viruses can become
resistant to these drugs, so these medications may not always
work. Additional studies are needed to prove the effectiveness
of these medicines.
What is the risk to humans
from bird flu?
The risk from bird flu is generally low to most people because
the viruses occur mainly among birds and do not usually infect
humans. However, during an outbreak of bird flu among poultry
(domesticated chicken, ducks, turkeys), there is a possible
risk to people who have contact with infected birds or surfaces
that have been contaminated with excretions from infected birds.
The current outbreak of avian influenza A (H5N1) among poultry
in Asia and Europe (see below) is an example of a bird flu
outbreak that has caused human infections and deaths. In such
situations, people should avoid contact with infected birds
or contaminated surfaces, and should be careful when handling
and cooking poultry. For more information about avian influenza
and food safety issues, visit the World
Health Organization website. In rare instances, limited
human-to-human spread of H5N1 virus has occurred, and transmission
has not been observed to continue beyond one person.
What is an avian influenza
A (H5N1) virus?
Influenza A (H5N1) virus – also called “H5N1 virus” – is
an influenza A virus subtype that occurs mainly in birds. Like
all bird flu viruses, H5N1 virus circulates among birds worldwide,
is very contagious among birds, and can be deadly.
What is the H5N1 bird flu
that has been reported in Asia and Europe?
Outbreaks of 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 outbreak. By March 2004, the
outbreak was reported to be under control. Beginning in late
June 2004, however, new outbreaks of influenza H5N1 among poultry
were reported by several countries in Asia (Cambodia, China
[ Tibet ], Indonesia, Kazakhastan, Malaysia, Mongolia, Russia
[ Siberia ], Thailand, and Vietnam). It is believed that these
outbreaks are ongoing. Most recently, influenza H5N1 has been
reported among poultry in Turkey and Romania. Human infections
of influenza A (H5N1) have been reported in Cambodia, Indonesia,
Thailand, and Vietnam.
What is the risk to humans
from the H5N1 virus in Asia and Europe?
The H5N1 virus does not usually infect humans. In 1997. However,
the first case of spread from a bird to a human was seen during
an outbreak of bird flu in poultry in Hong Kong, Special Administrative
Region. The virus caused severe respiratory illness in 18 people,
6 of whom died. Since that time, there have been other cases
of H5N1 infection among humans. Recent human cases of H5N1
infection that have occurred in Cambodia, Thailand, and Vietnam
have coincided with large H5N1 outbreaks in poultry. The World
Health Organization (WHO) also has reported human cases
in Indonesia. Most of these cases have occurred from contact
with infected poultry or contaminated surfaces; however, it
is thought that a few cases of human-to-human spread of H5N1
So far, spread of H5N1 virus from person to person has been
rare and has not continued beyond one person. However, because
all influenza viruses have the ability to change, scientists
are concerned that the 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 the H5N1 virus were able to infect people and
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
very closely and are preparing for the possibility that the
virus may begin to spread more easily and widely from person
How is infection with H5N1
virus in humans treated?
The H5N1 virus currently infecting birds in Asia that has caused
human illness and death 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 flu caused by the H5N1 virus, but additional
studies still need to be done to prove their 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 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 underway. For more information about the H5N1 vaccine development
process, visit the National
Institutes of Health website.
What is the risk to people
in the United States from the H5N1 bird flu outbreak
in Asia and Europe?
The current risk to Americans from the H5N1 bird flu outbreak
in Asia is low. The strain of H5N1 virus found in Asia and
Europe has not been found in the United States . There have
been no human cases of H5N1 flu in the United States . It is
possible that travelers returning from affected countries in
Asia could be infected if they were exposed to the virus. Since
February 2004, medical and public health personnel have been
watching closely to find any such cases.