pandemic

1. Influenza
By: Dr. Saurabh Agrawal

2. Intro
• Acute resp tract infec
• Caused by influenza virus A B C
• All pandemics were due to A strain
• Characterized by
– Sudden onset of chills
– Malaise
– Fever
– Muscular pain and cough

5. Problem statement
• International disease
• Affect million of people every yr
• May occur in pandemic every 10-40yrs due to
antigenic changes
– 1918= spanish influenza
– 1957= asian
– 1968= hong kong
• In b/w pandemic epidemic occur in
– A strain= 2-3 yr
– B strain= 4-7 yr

6. • Epidemic-
– Few cases- sudden outburst of disease-
hospitalization- school absentism
• 10-50% infec rate
• Peak of disease- 3-4 weeks
• 3 virsus
– A (H1N1)
– A (H3N2)
– B virus
– Recent A (H1N1) swine 2009 mexico

7. Agent fac
• Classified in – orthomyxoviridae
• A B C subtypes
• Antigenically different with no cross immunity
• A – 2 surface antigen
– H- haemagglutinin- initiates infec. On suseptable cell
– N- Neuraminidase- release of virus of infec. Cell
• Humans H1, H2, H3, N1, N3
• No subtype in B

8. Cont..
• A= unique due frequent antigenic variation
• SHIFT- sudden complete/ major change
• DRIFT- gradual over time change
• Due to interaction with animals
• Less antigenic change in B C

9. Influenza Virus Transmission
Three ways:
 Direct contact with infected individuals;
 Contact with contaminated objects (called fomites,
such as toys, doorknobs); and
 Inhalation of virus-laden aerosols.

10. • Reservoir-
– Major in animal and birds like swine-, horse, dog
cat poultry wild birds
• Source- case/ subclinical case
• Period of infecti- 1-2 days before and 1-2 days
after onset of symp

11. Host fac
• Age and sex- all ages, sexes
– Lower in adults
– More in high risk like old, below 18 yrs, diabetics,
CVD

12. Environmental fac
• Season- winter in northern hemis
– Winter/ rains in southern
• Overcrowding
• Incubation – 18- 72 hrs

13. Pathgenesis
• Enters RT- inflammation and necrosis of
tracheal and broncheal mucose- secondary
bac. infec

15. Lab diagnosis
• Virus isolation-
– Nasopharengeal secretion
• Serology-
– HI (inhibition
– ELISA

16. Prevention
• Little success
• Good ventilation, avoid crowded place, face
mask, handkerchief,
• Vaccine not recommended to control spread
• Vaccine- killed
– .5 ml / .25ml (6-36mth) SC/ IM
– Below 9 yrs 2 doses, saperate by 3-4 weeks
– 70-90% protection
– 6-12 months immunity
• Live attenuted- spray intra nasal

17. Treatment
• Oseltamavir
– 75 mg/day prophylaxis
– 75mg/day BD x 5 day
• Zanamavir
– Nasal spray 10 mg od for prophylaxis and BD for
treatment

18. Avian Influenza
Avian influenza is an infectious disease of birds
caused by type A strains of the influenza virus.
These viruses occur naturally among wild aquatic
birds worldwide and can infect domestic poultry and
other bird and animal species. The disease, which was
first identified in Italy more than 100 years ago.

19. Avian Influenza
 Fifteen subtypes of influenza virus are known to
infect birds, thus providing an extensive reservoir of
influenza viruses potentially circulating in bird
populations.
 H5N1; the strain of avian flu known as has been
behind outbreaks of deadly avian flu.

20. Avian Influenza
 Avian influenza transmitted by birds usually through
feces or saliva.
 Avian influenza is not usually passed on to humans,
although it has been contracted by people who have
handled infected birds or touched surfaces
contaminated by the birds.

21. Avian Influenza
 Low pathogenicity (LPAI) - usually only causing
mild respiratory disease in domestic poultry .
 High pathogenicity (HPAI) - the more virulent type
formerly known as fowl plague which often results in
up to a 100% flock mortality.

22. Source: WHO

23. Swine Flu
 Swine influenza (swine flu) is a respiratory disease of
pigs caused by type A influenza virus that regularly
cause outbreaks of influenza in pigs.
 Like human influenza viruses, there are different
subtypes and strains of swine influenza viruses. The
main swine influenza viruses circulating in U.S. pigs
in recent years are: H1N1 influenza virus, H3N2
virus, H1N2 virus.

24. Swine Flu
 Influenza in swine was first recognized as an
epizootic disease in 1918.
 Swine influenza virus was first isolated from humans
in 1974. Serologic evidence of infections with a
swine influenza virus in humans has also been
obtained. Viruses of swine may be a potential source
of epidemic disease for humans.

25. Swine Flu
Symptoms and Signs/ In pigs
 Fever, lethargy, sneezing, coughing, difficulty
breathing and decreased appetite.
Although mortality is usually low (around 1–4%), the
virus can produce weight loss and poor growth, causing
economic loss to farmers.
 In some cases, the infection can cause abortion.

26. Swine Flu
Symptoms and Signs/In Human
Systemic: fever
Nasopharynx: Runny nose; sore throat
Respiratory: Coughing
Gastric: Nausea; Vomiting
Intestinal: Diarrhea
Psychological: Lethargy; Lack of appetite

27. Source: WHO

28. The H1N1

29. H1N1/H5N1

30. Seasonal flu/ Pandemic flu
 Epidemic (seasonal) influenza which occurs annually
and is attributable to minor changes in genes that
encode proteins on the surface of circulating influenza
viruses. These are known as interpandemic epidemics.
 Pandemic influenza which occurs when more
significant changes in the influenza A virus arises when
human virus strains acquire genes from influenza
viruses of other animal species. When this happens,
everyone in the world is susceptible to the new virus,
and a worldwide epidemic or pandemic can result.