2. WHAT IS INFLUENZA?
Influenza, commonly called
"the flu," is an illness caused
by RNA viruses of
the family Orthomyxoviridae
the influenza viruses that
infect the respiratory tract of
many animals, birds, and
humans.
3. WHAT IS ORTHOMYXOVIRIDAE?
The Orthomyxoviridae are a
family of RNA viruses that
includes five genera:
Influenzavirus A, Influenzavirus
B, Influenzavirus C, Isavirus and
Thogotovirus. A sixth has recently
been described. The first three
genera contain viruses that cause
influenza in vertebrates, including
birds (see also avian
influenza), humans, and other
mammals. Isaviruses infect
salmon; thogotoviruses infect
vertebrates and
invertebrates, such as mosquitoes
and sea lice.
4. INFLUENZA VIRUSES ARE DIVIDED INTO THREE TYPES:
Influenza A
Influenza B
Influenza C
5. INFLUENZA A
Influenza A
Type A viruses are divided
into types based on
differences in two viral
surface proteins called the
hemagglutinin (H) and the
neuraminidase (N).
Influenza type A viruses
undergo two kinds of
changes:
Antigenic drift.
Antigenic shift.
6. INFLUENZA A (H1N1)
'Influenza' A (H1N1) virus is a
subtype of influenza A virus and
was the most common cause of
human influenza (flu) in 2009.
Some strains of H1N1 are
endemic in humans and cause a
small fraction of all influenza-like
illness and a small fraction of all
seasonal influenza. H1N1
(pronounced "HEE-NEE" by
healthcare professionals) strains
caused a few percent of all
human flu infections in 2004–
2005. Other strains of H1N1 are
endemic in pigs (swine influenza)
and in birds (avian influenza)
7. In June 2009, the World Health Organization
declared the new strain of swine-origin H1N1 as a
pandemic. This strain is often called swine flu by
the public media. This novel virus spread worldwide
and had caused about 17,000 deaths by the start of
2010. On August 10, 2010, the World Health
Organization declared the H1N1 influenza
pandemic over, saying worldwide flu activity had
returned to typical seasonal patterns
8. SWINE INFLUENZA
Swine influenza (also called swine flu, or pig flu)
is an infection by any one of several types of
swine influenza virus. Swine influenza virus (SIV)
is any strain of the influenza family of viruses that
is endemic in pigs. As of 2009, the known SIV
strains include influenza C and the subtypes of
influenza A known as
H1N1, H1N2, H3N1, H3N2, and H2N3.
Swine influenza virus is common throughout pig
populations worldwide. Transmission of the virus
from pigs to humans is not common and does not
always lead to human influenza, often resulting
only in the production of antibodies in the blood.
If transmission does cause human influenza, it is
called zoonotic swine flu. People with regular
exposure to pigs are at increased risk of swine flu
infection. The meat of an infected animal poses
no risk of infection when properly cooked.
Pigs experimentally infected with the strain of
swine flu that is causing the current human
pandemic showed clinical signs of flu within four
days, and the virus spread to other uninfected
pigs housed with the infected ones.
9. AVIAN INFLUENZA
Avian influenza — known informally as
avian flu or bird flu — refers to
"influenza caused by viruses adapted to
birds."Of the greatest concern is highly
pathogenic avian influenza (HPAI).
"Bird flu" is a phrase similar to "swine
flu," "dog flu," "horse flu," or "human flu"
in that it refers to an illness caused by
any of many different strains of influenza
viruses that have adapted to a specific
host. All known viruses that cause
influenza in birds belong to the species
influenza A virus. All subtypes (but not
all strains of all subtypes) of influenza A
virus are adapted to birds, which is why
for many purposes avian flu virus is the
influenza A virus. (Note, however, that
the "A" does not stand for "avian").
10. THE FLU PANDEMIC
In the 2009 flu pandemic, the virus isolated from patients in the
United States was found to be made up of genetic elements from
four different flu viruses – North American swine influenza, North
American avian influenza, human influenza, and swine influenza
virus typically found in Asia and Europe – "an unusually
mongrelised mix of genetic sequences." This new strain appears
to be a result of reassortment of human influenza and swine
influenza viruses, in all four different strains of subtype H1N1.
Preliminary genetic characterization found that the hemagglutinin
(HA) gene was similar to that of swine flu viruses present in U.S.
pigs since 1999, but the neuraminidase (NA) and matrix protein
(M) genes resembled versions present in European swine flu
isolates. The six genes from American swine flu are themselves
mixtures of swine flu, bird flu, and human flu viruses. While
viruses with this genetic makeup had not previously been found
to be circulating in humans or pigs, there is no formal national
surveillance system to determine what viruses are circulating in
pigs in the U.S
11. INFLUENZA B
Influenza type B viruses
change only by the more
gradual process of
antigenic drift.
12. INFLUENZA C
Type C infection usually
causes either a very mild
respiratory illness or no
symptoms at all;
13. SIGNS AND SYMPTOMS
Fever (usually 100 F-103 F
in adults and often even
higher in children)
Cough,
Sore throat,
Runny or stuffy nose,
Headache,
Muscle aches,
Extreme fatigue
14. MODE OF TRANSMISSION
Influenza is spread
mainly from person to
person by droplet
infection or droplet
nuclei created by
sneezing, coughing or
talking. The portal of
entry of the virus is the
respiratory tract.
15. DIAGNOSIS
Virus Isolation
Nasopharyngeal secretions
are the best specimens for
obtaining large quantities of
virus–infected cells.
Paired Sera
A sero diagnosis of influenza
A or B can be made by the
examination of two serum
specimens from a patient.
16. PREVENTION
Vaccine:
The ―flu shot‖ — an
inactivated vaccine
(containing killed virus) that is
given with a needle, usually
in the arm.
The nasal-spray flu
vaccine — a vaccine made
with live, weakened flu
viruses that is given as a
nasal spray (sometimes
called LAIV for ―Live
Attenuated Influenza
Vaccine‖).
17. MEDICATIONS
Increasing liquid intake, warm
showers, and warm
compresses, especially in the
nasal area, can reduce the
body aches and reduce nasal
congestion. Nasal strips and
humidifiers may help reduce
congestion, especially while
trying to sleep. Fever can be
treated with over-the counter
acetaminophen (Tylenol)
or ibuprofen (Motrin and
others)
