infecious virus

2. Swine flu (swine influenza) is a disease of pigs. It is a highly contagious
respiratory disease caused by one of many Influenza A viruses.
Approximately 1% to 4% of pigs that get swine flu die from it. It is spread
among pigs by direct and indirect contact, aerosols, and from pigs that
are infected but do not have symptoms. In many parts of the world pigs
are vaccinated against swine flu.
Most commonly, swine flu is of the H1N1 influenza subtype. However,
they can sometimes come from the other types, such as H1N2, H3N1,
and H3N2.
The current outbreak of swine flu that has infected humans is of the
H1N1 type - this type is not as dangerous as some others. Avian Influenza
(Bird Flu) can also infect pigs
Avian flu and human seasonal flu viruses can infect pigs, as well as swine
influenza. The H3N2 influenza virus subtype, a virulent one, is thought to have
come from pigs - it went on to infect humans.
It is possible for pigs to be infected with more than one flu virus subtype
simultaneously. When this happens the genes of the viruses have the
opportunity to mingle. When different flu subtypes mix they can create a new
virus which contains the genes from several sources - a reassortant virus.

3. What is swine flu?
 Swine Influenza (swine flu) is a
respiratory disease of pigs
caused by Type A influenza
viruses that causes regular
outbreaks in pigs.
 Swine flu viruses have been
reported to spread from person-
to-person, but in the past, this
transmission was limited and
not sustained beyond three
people.

4.  Influenza A (H1N1) virus is the subtype of influenza
A virus that was the most common cause of
human influenza (flu) in 2009. It is an
Orthomyxovirus that contains the glycoproteins
Haemagglutinin and Neuraminidase. For this reason,
they are described as H1N1, H1N2 etc. depending
on the type of H or N antigens they express.
Haemagglutin causes red blood cells to clump
together and binds the virus to the infected cell.
Neuraminidase are a type of glycoside hydrolase
enzyme which help to move the virus particles
through the infected cell and assist in budding from
the host cells

5. Swine Flu History and Overview
Influenza viruses are small RNA viruses that infect many mammals, including
humans, birds, and swine. Before 2009, swine influenza predominately
affected swine and was not transmitted often or easily to people
Before 2009, there was only one swine influenza outbreak in people that
caused public-health concerns. This outbreak occurred in 1979, in soldiers at
Fort Dix, N.J. One recruit died, and approximately 12 were hospitalized with
influenza
The lessons learned from the 1979 swine influenza event were applied in
dealing with pandemic threats, including the severe acute respiratory
syndrome (SARS) outbreak of 2003 and the 2009 influenza outbreak
In 2011-2012, another outbreak occurred with a variant influenza virus strain
termed H3N2v. The "v" indicated the strain that only usually infected swine
was found to infect humans. Fortunately, the strain is not transmitted easily
from human to human, and since 2011, only about 329 individuals have been
infected

6. The 2009 and 2011 Outbreaks of Swine Influenza
 In March and April 2009, hundreds of cases of human respiratory
illness were reported in Mexico that were suspected or confirmed
to be caused by a novel swine-type influenza virus. By April,
confirmed cases were also reported in the United States.
 The World Health Organization (WHO) officially declared the
2009 swine flu to be a pandemic. The U.S. Centers for Disease
Control and Prevention (CDC) estimated that more than 1 million
Americans were infected with swine influenza by June 2009. By
August 2009, more than 170 countries and territories reported
swine flu cases. By October, 46 U.S. states were reporting
widespread outbreaks. By late October, the virus had been
confirmed to have caused more than 1,000 deaths in the U.S.,
with almost 100 of the deaths in children


7.  In 2011, the CDC reported a new assortment of genetic
material from H1N1 and H3N2 influenza A viruses that
resulted in a new strain of swine virus termed influenza A
(H3N2)v (also termed H3N2v) that was similar to viruses that
infected pigs in the 1990s. However, this strain genetically
picked up an M gene from H1N1 that researchers suggest
allowed the viral strain to more easily infect humans. In the fall
of 2011, the CDC reported that about 12 confirmed human
infections were detected in young people who often had some
association with pigs or pig farming

8. Swine Flu Cause
 Influenza viruses are named according to the types of
proteins on the outer surface of the virus. The two main
proteins are hemagglutinin (H) and neuraminidase (N).
The swine influenza virus in the 2009 outbreak was an
H1N1 virus. In fact, although the term swine flu is often
used to describe the outbreak, the official term for the
2009 virus is novel H1N1 influenza
 The 2009 novel H1N1 swine influenza strain appeared to
be a result of genetic shift, meaning that it contains pieces
of influenza from many different sources. The 2009 virus
included genes that come from bird influenza viruses,
swine influenza viruses, and human influenza viruses.
This strain had not previously caused infections in
humans or pigs. Thus, it was unlikely that most humans
had preexisting immunity to this new strain.
.

9. Swine Flu Transmission
 Swine influenza (novel H1N1 and H3N2v) spreads from
person to person, either by inhaling the virus or by
touching surfaces contaminated with the virus, then
touching the mouth or nose. Infected droplets are expelled
into the air through coughing or sneezing. H3N2v does not
spread as easily from person to person as H1N1. This
poor transmission rate is likely why there have been so
few individuals infected with H3N2v.
 Research suggested that H1N1 swine influenza is about
as contagious as the usual human influenza. If one person
in a household gets swine flu, anywhere from 8%-19% of
household contacts likely will get infected. Reports from
the southern hemisphere suggest that swine influenza
caused slightly more infections than would be normal for
an influenza season

10. Pandemic Influenza
Intervals
D
Accel-
eration
C
Initiation
E
Peak
Transmission
F
Deceleration
G
Resolution
B
Recognition
A
Investigation

11. Signs and symptoms
Symptoms of novel H1N1 flu in people are similar to
those associated with seasonal flu.
• Fever
• Cough
• Sore throat
• Runny or stuffy nose
• Body aches
• Headache
• Chills
• Fatigue
• In addition, vomiting (25%) and diarrhea
(25%) have been reported. (Higher rate than for
seasonal flu.)

12. How does novel H1N1 Influenza
spread?
 This virus is thought to spread the
same way seasonal flu spreads
 Primarily through respiratory droplets
 Coughing
 Sneezing
 Touching respiratory droplets on
yourself, another person, or an
object, then touching mucus
membranes (e.g., mouth, nose,
eyes) without washing hands

13. Influenza Like Illness
 Must-have symptoms
 Fever plus sore throat or
 Fever plus cough
 Other symptoms
 Headache
 Muscle & joint aches
 Nausea, vomiting, or diarrhea
 Fatigue
 Pneumonia
 Shortness of breath

14. Watch for emergency warning
signs
Most people should be able to recover at home, but
watch for emergency warning signs that mean you
should seek immediate medical care.
In adults:
• Difficulty breathing or shortness of breath
• Pain or pressure in the chest or abdomen
• Sudden dizziness
• Confusion
• Severe or persistent vomiting
• Flu-like symptoms improve but then return
with
fever and worse cough

15. Emergency warning signs in
children
If a child gets sick and experiences any of these
warning signs, seek emergency medical care.
In children:
 Fast breathing or trouble breathing
 Bluish or gray skin color
 Not drinking enough fluids
 Severe or persistent vomiting
 Not waking up or not interacting
 Irritable, the child does not want to be held
 Flu-like symptoms improve but then return
with fever and worse cough

16. Swine Flu Diagnosis
 Swine influenza can be confirmed by culturing respiratory
secretions such as sputum or nasal/throat secretions, but
this is expensive and not often done. Rapid tests are
available to give a general idea if an influenza strain is
present, but they are far from perfect and may not pick up
swine influenza or even regular seasonal influenza. In fact,
the CDC does not recommend the use of rapid tests
because the results are often inaccurate. Specific testing
for the genetic material of the virus, such as the test
called polymerase chain reaction or PCR, may be done at
state health departments or at the CDC. Your local
laboratory will have a procedure in place to send
specimens to the health department when necessary. H1N1
and H3N2v strains are detected with similar methods, and
new tests are being produced to detect these strains
quickly and economically in hospitals and clinics (most will
test only for H1N1 and possibly H3N2).

17. Treatment
 Laboratory testing has shown that the 2009 swine
influenza strain is sensitive to two antiviral medicines
that are used to treat human influenza. They
are oseltamivir (Tamiflu) and zanamivir (Relenza).
Oseltamivir is given in pill form. Zanamivir is an inhaled
medication. Both medications require a prescription.
The drugs should be given to people who appear to
have swine influenza if they have chronic medical
conditions that put them at risk for complications (see
above) or if they are unusually ill. These drugs can be
used for patients with either H1N1 or H3N2v infections.
A few drug-resistant H1N1strains have been reported,
but most swine flu strains remain sensitive. Older
drugs like amantadine(Symmetrel) are not effective

18. Is there a vaccine for Pandemic Flu?
 Because the virus is new, there will be no
vaccine ready to protect against pandemic
flu.
 Vaccine against Swine Flu virus H1N1 needs
at least 6-12 months to be produced.
 Seasonal flu vaccine or past flu immunization
will not provide protection.

19. Swine Flu Prevention
 . During coughs and sneezes, the mouth should be
covered with a tissue or a sleeve. In areas with large
numbers of cases, it is best to minimize nonessential
exposure to crowds. Sick people should stay home
whenever possible.
 To reduce the risk of spreading the flu to other family
members, everyone in the household should wash
their hands frequently. Alcohol-based sanitizing gels
are available in stores and may be used instead of
soap and water when hands are not visibly soiled.

20. Thanks a lot