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Pandemic
Flu: Frequently Asked Questions FAQ
Key
General
What
is an influenza pandemic?
A pandemic is a global disease outbreak. An influenza pandemic
occurs when a new influenza A virus emerges for which there is
little or no immunity in the human population, begins to cause
serious illness, and then spreads easily person-to-person worldwide.
Is
a pandemic imminent? Will the flu hit us soon?
Many scientists believe it is a matter of time until the next
influenza pandemic occurs. However, the timing and severity of
the next pandemic cannot be predicted. Influenza pandemics occurred
three times in the past century - in 1918-19, 1957-58, and 1968-69.
How
do pandemic viruses occur?
New influenza viruses emerge as a result of a process called antigenic
shift, which causes a sudden and major change in influenza A viruses.
These changes occur when proteins on the surface of the virus
combine in new ways as a result of mutation or exchange of genetic
material between multiple influenza viruses. If such changes result
in a new influenza A virus subtype that can infect humans and
spread easily from person to person, an influenza pandemic can
occur.
What
age groups are most likely to be affected during an influenza
pandemic?
Although scientists cannot predict the specific consequences of
an influenza pandemic, it is likely that many age groups would
be seriously affected. The greatest risk of hospitalization and
death - as seen during the last two pandemics in 1957 and 1968
and during annual influenza - will be infants, the elderly, and
those with underlying health conditions. However, in the 1918
pandemic, most deaths occurred in young adults. Few if any people
would have immunity to the virus.
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, acting as reservoirs, carry a normally harmless
form of influenza viruses in their intestines, and wild birds
usually do not get sick from them. Unlike most avian influenza
viruses, however, this new strain of H5N1 has caused mortality
in more than 80 species of wild birds. Avian influenza can be
very contagious among domestic poultry, 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. Wild bird avian influenza viruses
of low pathogenicity mix with avian viruses in domesticated birds
and become highly pathogenic in poultry. Domestic poultry 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 droppings that harbor
the low-pathogenicity the virus.
How
do people become infected with avian influenza viruses?
Most cases of H5N1 avian influenza infection in humans have resulted
from direct or close contact with infected poultry (e.g., domesticated
chicken, ducks, and turkeys) or surfaces possibly contaminated
from feces of infected birds. For a pandemic of influenza to occur,
avian influenza must mutate/change to be able to be passed easily
from person to person. A pandemic of influenza can arise from
changes that occur in certain kinds of highly pathogenic bird
flu but no one knows when or even if this will happen. Today,
there have been no reported cases of sustained human-to-human
transmission of avian flu.
What
are the symptoms of avian influenza in humans?
People infected with the current strand of the avian virus (H5N1)
have shown everything from typical human influenza-like symptoms
(fever, cough, sore throat, and muscle aches) to pneumonia, severe
respiratory diseases, and other life-threatening complications.
Symptoms of avian influenza may depend on which specific virus
subtype and strain caused the infection.
Could
terrorists spread the avian influenza viruses to create a worldwide
pandemic?
Experts believe it highly unlikely that a pandemic influenza virus
could be created by terrorists. Developing a pandemic influenza
virus would require extraordinary scientific skill as well as
sophisticated scientific equipment and other resources.
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