A presentation for Medicos on H1N1

1. - P.Akshay Khumar

2. Introduction…
• It is an enveloped RNA virus from the
Orthomyxovirus family
• Influenza viruses are classified based on
antigenic structures on the envelope called
neuraminidase “N” and haemagglutinin “H”.
• This illness is referred as "Swine Flu" because
the genes of this virus strain were found to be
similar to influenza virus occurring in pigs in
North America.

3. Etiology…
• Swine flu is contagious, and it spreads in the same
way as the seasonal flu.
• When people who have it cough or sneeze, they
spray tiny drops of the virus into the air. If you
come in contact with these drops or touch a
surface that an infected person has recently
touched, you can catch H1N1 swine flu.
• They survive for 2-8 hours after being deposited
on the surface
• Despite the name, you can't catch swine flu from
eating bacon, ham, or any other pork product.

4. Genetic reassortment….
• Pigs serves as site of genetic reassortment
• Pigs may be simultaneously affected by Swine
and human influenza virus.
• Even bird flu from faeces of birds
• The virus has segmented RNA and during
replication they may get mixed up
• Antigenic Shift

6. Pathogenisis…
• People in close contact with the pigs acquire
the infection
• After inhalation, the virus gets deposited on
the surface of the lower respiratory tract
• The estimated incubation period in humans is
unknown and more likely 1-4 days
• Patient may be contagious from one day before
they develop symptoms to up to 7 days after
they get sick.

7. Contd…
• Bronchial and mediastinal lymph nodes get enlarged.
• Sharp line of demarcation between normal and affected
lung tissue can be identified with the affected tissue
being purple and firm.
• Interlobular edema can be found in few cases.
• Airways get filled up with blood-tinged fibrinous
exudates with peribronchial and perivascular cellular
infiltration.
• Fibrinous pleuritis is seen in severe cases.
• Microscopically lesions show airways filled with
exudate, with extensive alveolar atelectasis, interstitial
pneumonia and emphysema.
• Research revealed that widespread interstitial pneumonia
causes hemorrhagic lymph nodes.

8. Symptoms….
• Most symptoms are the same as seasonal flu. They can
include:
• cough
• fever
• sore throat
• stuffy or runny nose
• body aches
• headache
• chills
• Fatigue
• Rashes
• Vomitting and diarrhoea

9. Diagnosis…
• Clinically by History ( Association with people
having the above symptoms)
• Nasopharyngeal swab to distinguish type A and B
• If Type A, more chances of swine flu
• Swine flu is definitively diagnosed by identifying
the particular antigens (surface proteins)
associated with the virus type in specialized
laboratories by PCR
• CDC recommended only hospitalized patients' flu
virus strains be sent to reference labs to be
identified

10. Vaccination…
• The best treatment for influenza infections in humans
is prevention by vaccination
Nasal Spray:
The first H1N1 vaccine released in early October 2009
was a nasal spray vaccine that was approved for use in
healthy individuals ages 2-49
• The nasal spray vaccine contains live virus that have
been altered to hinder its ability to replicate in human
tissue. People with a suppressed immune system
should not get vaccinated with the nasal spray

11. The injectable vaccine:
• The injectable vaccine, made from killed H1N1,
became available in the second week of Oct.
2009. This vaccine was approved for use in ages
6 months to the elderly, including pregnant
females.
• The flu shot (vaccine) is made from killed virus
particles so a person cannot get the flu from a
flu shot

12. Intradermal (trivalent) vaccine
• A new influenza vaccine preparation is the intradermal (trivalent)
vaccine is available; it works like the shot except the
administration is less painful. It is approved for ages 18-64 years.
“Most vaccinies are derived from
Egg culture technique”
Adverse effects of vaccination:
• Flu shot: Soreness, redness, minor swelling at the shot site,
muscle aches, low-grade fever, and nausea
• Nasal spray: runny nose, low-grade fever, vomiting, headache,
wheezing, cough, and sore throat
• Intradermal shot: redness, swelling, pain, headache, muscle
aches, fatigue

13. Antiviral agents:
• Two antiviral agents have been reported to help prevent or
reduce the effects of swine flu. They are zanamivir (Relenza)
and oseltamivir (Tamiflu)
• These drugs should not be used indiscriminately, because viral
resistance to them can and has occurred.
• Also, they are not recommended if the flu symptoms already
have been present for 48 hours or more
• Hospitalized patients may still be treated past the 48-hour
guideline.
• Pregnant females can be treated with the two antiviral agents.