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Influenza
A(H1N1):
fact sheet Q & A
Source:
http://www.who.int/csr/disease/swineflu/faq/en/
What is Pandemic
H1N1 2009?
Pandemic H1N1 2009, or “swine flu”, is a highly contagious acute respiratory
disease of pigs, caused by one of several Pandemic H1N1 2009 A viruses. Morbidity tends
to be high and mortality low (1-4%). The virus is spread among pigs by
aerosols, direct and indirect contact, and asymptomatic carrier pigs. Outbreaks
in pigs occur year round, with an increased incidence in the autumn and winter
in temperate zones. Many countries routinely vaccinate swine populations
against Pandemic H1N1 2009.
Pandemic H1N1 2009 viruses are
most commonly of the H1N1 subtype, but other subtypes are also circulating in
pigs (e.g., H1N2, H3N1, H3N2). Pigs can also be
infected with avian influenza viruses and human seasonal influenza viruses as
well as Pandemic H1N1 2009 viruses. The H3N2 swine virus was thought to have been
originally introduced into pigs by humans. Sometimes pigs can be infected with
more than one virus type at a time, which can allow the genes from these
viruses to mix. This can result in an influenza virus containing genes from a
number of sources, called a "reassortant"
virus. Although Pandemic H1N1 2009 viruses are normally species specific and only
infect pigs, they do sometimes cross the species barrier to cause disease in
humans.
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What are the implications
for human health?
Outbreaks and sporadic
human infection with Pandemic H1N1 2009 have been occasionally reported. Generally
clinical symptoms are similar to seasonal influenza but reported clinical
presentation ranges broadly from asymptomatic infection to severe pneumonia
resulting in death.
Since typical clinical
presentation of Pandemic H1N1 2009 infection in humans resembles seasonal
influenza and other acute upper respiratory tract infections, most of the cases
have been detected by chance through seasonal influenza surveillance. Mild or
asymptomatic cases may have escaped from recognition; therefore the true extent
of this disease among humans is unknown.
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Where have human
cases occurred?
Since the implementation of
IHR(2005)1 in 2007, WHO has been notified
of Pandemic H1N1 2009 cases from the United States
and Spain.
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How do people
become infected?
Humans usually contract
Pandemic H1N1 2009 from infected pigs, however, some cases lack contact history
with pigs or environments where pigs have been located. Human-to-human
transmission has occurred in some instances but was limited to close contacts
and closed groups of people.
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Is it safe to eat pork
and pork products?
Yes.
Pandemic H1N1 2009 has
not been shown to be transmissible to people through eating properly handled
and prepared pork (pig meat) or other products derived from pigs. The Pandemic
H1N1 2009 virus is killed by cooking temperatures of 160°F/70°C, corresponding
to the general guidance for the preparation of pork and other meat.
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Which countries
have been affected by outbreaks in pigs?
Pandemic H1N1 2009 is not notifiable to international animal health authorities (OIE,
www.oie.int), therefore its
international distribution in animals is not well known. The disease is
considered endemic in the United
States. Outbreaks in pigs are also known to
have occurred in North America, South America, Europe (including the UK, Sweden,
and Italy), Africa (Kenya), and in parts of eastern Asia including China and Japan.
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What about
the pandemic risk?
It is likely that most
people, especially those who do not have regular contact with pigs, do not have
immunity to Pandemic H1N1 2009 viruses that can prevent the virus infection. If a
swine virus establishes efficient human-to human transmission, it can cause an
influenza pandemic. The impact of a pandemic caused by such a virus is
difficult to predict: it depends on virulence of the virus, existing immunity
among people, cross protection by antibodies acquired from seasonal influenza
infection and host factors.
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Is
there a human vaccine to protect against Pandemic H1N1 2009?
There are no vaccines that
contain the current Pandemic H1N1 2009 virus causing illness in humans. It is not
known whether current human seasonal influenza vaccines can provide any
protection. Influenza viruses change very quickly. It is important to develop a
vaccine against the currently circulating virus strain for it to provide
maximum protection to the vaccinated people. This is why WHO needs access to as
many viruses as possible in order to select the most appropriate candidate
vaccine virus.
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What medicines are
available for treatment?
There are two classes of
such medicines, 1) adamantanes (amantadine
and remantadine), and 2) inhibitors of influenza
neuraminidase (oseltamivir and zanamivir).
Most of the previously
reported Pandemic H1N1 2009 cases recovered fully from the disease without
requiring medical attention and without antiviral medicines.
Some influenza viruses
develop resistance to the antiviral medicines, limiting the effectiveness of
treatment. The viruses obtained from the recent human cases with Pandemic H1N1
2009 in the United
States are sensitive to oselatmivir
and zanamivir but resistant to amantadine
and remantadine.
Information is insufficient
to make recommendations on the use of the antivirals
in treatment of Pandemic H1N1 2009 virus infection. Clinicians should make
decisions based on the clinical and epidemiological assessment and harms and
benefits of the treatment of the patient2. For the ongoing outbreak
of the Pandemic H1N1 2009 infection in the United
States and Mexico, national and local
authorities are recommending use oseltamivir or zanamivir for treatment of the disease based on the virus’s
susceptibility profile.
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What should I do if I am
in regular contact with pigs?
Even though there is no
clear indication that the current human cases with Pandemic H1N1 2009 infection
are related to recent or ongoing influenza-like disease events in pigs, it
would be advisable to minimize contact with sick pigs and report such animals
to relevant animal health authorities.
Most people are infected
through prolonged, close contact with infected pigs. Good hygiene practices are
essential in all contact with animals and are especially important during
slaughter and post-slaughter handling to prevent exposure to disease agents.
Sick animals or animals that died from disease should not be undergoing
slaughtering procedures. Follow further advice from relevant national
authorities.
Pandemic H1N1 2009 has not
been shown to be transmissible to people through eating properly handled and
prepared pork (pig meat) or other products derived from pigs. The Pandemic H1N1
2009 virus is killed by cooking temperatures of 160°F/70°C corresponding
to the general guidance for the preparation of pork and other meat.
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How can I protect
myself from getting Pandemic H1N1 2009 from infected people?
In the past, human
infection with Pandemic H1N1 2009 was generally mild but is known to have caused
severe illness such as pneumonia For the current
outbreaks in the United States
and Mexico
however, the clinical pictures have been different. None of the confirmed cases
in the United States
have had the severe form of the disease and the patients recovered from illness
without requiring medical care. In Mexico, some patients reportedly
had the severe form of the disease.
To protect yourself,
practice general preventive measures for influenza:
If there is an ill person
at home:
- Try to provide the ill person a
separate section in the house. If this is not possible, keep the patient
at least 1 meter in distance from others.
- Cover mouth and nose when
caring for the ill person. Masks can be bought commercially or made using
the readily available materials as long as they are disposed of or cleaned
properly.
- Wash your hands with soap and
water thoroughly after each contact with the ill person.
- Try to improve the air flow in
the area where the ill person stays. Use doors and windows to take
advantage of breezes.
- Keep the environment clean with
readily available household cleaning agents.
If you are living in a
country where Pandemic H1N1 2009 has caused disease in humans, follow additional
advice from national and local health authorities.
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What
should I do if I think I have Pandemic H1N1 2009?
If you feel unwell, have
high fever, cough and/or sore throat:
-
Stay at home and keep away from
work, school or crowds as much as possible.
-
Rest and take plenty of fluids.
-
Cover your mouth and nose with
disposable tissues when coughing and sneezing and dispose of the used
tissues properly.
- Wash your hands with soap and
water frequently and thoroughly, especially after coughing or sneezing.
- Inform family and friends about
your illness and seek help for household chores that require contact with
other people such as shopping.
If you need medical
attention:
- Contact your doctor or
healthcare provider before travelling to see them and report your
symptoms. Explain why you think you have Pandemic H1N1 2009 (for example, if
you have recently travelled to a country where there is a Pandemic H1N1
2009
outbreak in humans). Follow the advice given to you for care.
- If it is not possible to
contact your healthcare provider in advance, communicate your suspicion of
having Pandemic H1N1 2009 immediately upon arrival at the healthcare
facility.
- Take care to cover your nose
and mouth during travel.
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