The document discusses influenza, also known as seasonal flu. It is an acute respiratory infection caused by influenza viruses that causes symptoms like fever, cough, and muscle pain. Influenza occurs seasonally as well as sporadically, and can sometimes cause pandemics every 10-40 years when the virus undergoes major antigenic changes. Influenza viruses are classified into types A, B, and C. Type A is responsible for epidemics and pandemics. The document outlines the epidemiology, transmission, clinical features, diagnosis, treatment and prevention of influenza. Vaccination is recommended for high-risk groups to reduce complications.

1. INFLUENZA
Dr. Deepak Upadhyay
Department of Community Medicine

2. Also know as ‘’SEASONAL
FLU’’
 Influenza is an ‘acute Respiratory tract
infection’ caused by influenza virus
characterized by sudden onset of chills,
malaise, fever, muscular pain and cough.
 Can occur as
Sporadic case / seasonal case
Epidemic case
Pandemic case

3. PROBLEM STATEMENT
• Its an international disease
• Occur in all countries and affect millions of
people
• May occur pandemic every 10-40 years due to
major antigenic changes as occurred in
-1918 - SPANISH INFLUENZA
-1957 - ASIAN INFLUENZA
-1968 - HONG KONG INFLUENZA
-2009 – H1N1 FLU

4. Epidemiological
Determinants

5. AGENT FACTOR

6. AGENT FACTOR
• Influenza virus, classified under
‘’Orthomyxovirs’’
• RNA virus
• Three sub types
• Type A
• Type B
• Type C
• Influenza A virus have 2 distinct
surface antigen
• Heamagglutinin (H) –
Attachment of virus to
susceptible cell
• Neuraminidase (N) - Release
of virus from infected cell

8. Type A Type B Type C
Causes
Significant
Disease
Causes Significant
Disease
Only in
apparent
cases
Epidemic &
Pandemic
Milder Epidemic
High Morbidity &
Mortality
Less Morbidity &
Mortality
Infect Human &
other species
Only human Only human
Antigenic
variations
frequently
Antigenic
variations
infrequent
Antigenic
variations
infrequent

9. What is antigenic shift
and drift
• Antigenic shift results from genetic
recombination of human and animal or avian
virus
• Antigenic Drift involve point mutation in the
gene
• Type B show lessor degree changes and Type C
is antigenically stable

10. RESERVOIR OF
INFECTION
• Major reservoir of human seasonal influenza
are animals and birds
• Human cases & subclinical cases – primary
reservoir
• Virus isolate from many animals and birds like
swine, horses , dogs, domestic poultry, and wild
birds etc.
• New stains form due to recombination between
man, animals and birds.
• Migratory waterfowls (wild duck) are natural
reservoir for Avian influenza

11. SOURCE OF INFECTION
• Cases or subclinical cases – Human seasonal
influenza
• During epidemic asymptomatic infection
occur, play important role in spread of
infection
• Respiratory tract secretions are also
infective
• Birds, poultry material infected with bird
excreta/secretions & birds meat – Avian
Flu

12. Period of infectivity
• Human Seasonal influenza
• 3-5 days from clinical onset – Adults
• 7 days from clinical onset – Children
• Highest infectivity – during 1st day
• Avian influenza – cases are not infective

13. HOST FACTOR

14. AGE and SEX
• All age groups and both sexes are affected
• Attack rate is lower among adults
• Children constitute an important link in
transmission chain

15. Mortality rate
• Highest mortality rate during epidemic
among
• Old People (generally over 85)
• Children under 18 months
• Person with systemic diseases such as:
- chronic heart disease CHD
- respiratory diseases
- renal disease
- diabetics person

16. IMMUNITY
• Appear – 7 days
• Drops to pre infection level – 12 months
• Specific antibodies against HA and NA
• Resistance to initiation of infection is
related to antibody against HA
• Decrease severity of disease and decrease
transmission related to NA

17. ENVIONMENTAL
FACTIOR

18. • SEASON
• Epidemic usually occur in winter month in
Temperate zone
• In Tropical zone outbreaks occur in rainy
season
• OVERCROWDING
- Enhance transmission

19. MODE OF TRANSMISSION
 Human seasonal influenza
 Person to person
 Droplet infection or droplet nuclei
 Use of fomites
 Portal of Entry - respiratory tract
 Avian influenza
Birds to human
Feco-oral route (excreta of poultry)
Direct contact
Ingestion of under cooked food

20. INCUBATION PERIOD
• Human seasonal influenza
1 to 4 days
• Avian influenza
2 to 5 days

21. PATHOGENSIS
Virus
Superficial Epithelium of respiratory tract
Inflammation
Necrosis

22. CLINICAL FEATURES
Human seasonal influenza
• Fever High grade
• Chills
• Significant Generalized ache and pain
• Headache, myalgia
• Coughing
• Generalized weakness and exhaustion
 Fever last for 1-5 days and average 3 days
in adults

23. Features Influenza Common cold
Fever High Uncommon
Headache Present Uncommon
Fatigue/Weakness Moderate Mild
Pain, aches Moderate Mild
Exhaustion Severe Absent
Stuffy nose &
Sore throat
Uncommon Common
Cough Present Uncommon

24. CLINICAL FEATURES
Avian influenza
• Fever high grade
• Generalized ache and pain
• Headache and myalgia
• Coughing (severe)
• Diarrhea
• Generalized weakness
• Signs of lower respiratory tract
infection

25. CLINICAL FEATURES
Pandemic influenza (H1N1 influenza)
Uncomplicated influenza
• Fever
• Cough, running nose
• Sore throat
• Muscle pain
• Malaise
• No dyspnea and
shortness of breath
• GIT symptom may also
present
Complicated influenza
• Shortness of breath and
dyspnea
• Lower RTI(pneumonia)
• CNS involvement
• Sever dehydration
• Secondary complications
• COPD asthma renal
failure

26. Specimens / samples
 Human seasonal influenza & Pandemic influenza
Nasal/nasopharyngeal swab
Oropharyngeal swab
Throat swab – not useful after 2 days of illness
 Avian influenza
Endotracheal swab
Nasal/nasopharyngeal swab
Oropharyngeal swab
Throat swab
 Transportation of sample – Triple packing system

27. LAB DIAGNOSIS
• VIRUS ISOLATION –
• Viral culture in egg culture (Gold Standard)
• Viral RNA can be detected by
• RT-PCR (best method for initial diagnosis)
• SERIOLOGY – antibodies detection by
 Heamagglutination inhibition (HI)
 ELISA
4 folds increase in titer between acute &
convalescent phase indicate the influenza
infection

28. Case management

29.  Symptomatic management
Cough suppression
Decongestants
Paracetamol for fever (Salicylates must be
avoided)
 Antiviral drugs
M2 inhibitors –Amantadine, Rimantadine
Neuraminidase inhibitors – Oseltamivir,
Zanamivir
Influenza A is treated with zanamivir or
combination of oseltamivir and rimantadine
Influenza B is treated with osaltamivir
 Supportive management
Oxygen therapy, Antibiotics, steroids etc.

30. PREVENTION

31. General Measures
• Good ventilation of public
buildings
• Avoid overcrowding specially
during epidemics
• Cover your mouth while
sneezing and coughing
• Immunization vaccine must
administrate at least 2 weeks
before the onset of epidemic
• Hand hygiene
• Personal protective equipment
• Persons of high risk of
transmission

32. VACCINE FOR SELECTED
POPULATION
• In industries to reduce absenteeism
• In public servants to prevent critical public
services
• Certain age groups like elders and children
under 18 month to prevent from sever
complications
• Also the people with chronic illness like systemic
diseased to prevent death
• Peoples travelling to epidemic/outbreak area

34. Killed vaccine (For Human
seasonal influenza)
• Required strains of vaccine are grown in allantonic
cavity of chick embryo
• Harvested purified and killed by beta-
propiolacton
• Formulation: Aqueous or Oil adjuvant
• Dose: (1/2 dose for Oil adjuvant)
• 0.5 ml for adults and children over 3 years
• 0.25 ml for children from 6 to 3 years

35. • Primary Doses – 2 doses 1 month apart
• Route - Subcutaneous
• Site of injection - Deltoid region
• Immunity duration
• Aqueous vaccine – 6 months
• Oil adjuvant vaccine – 1 year
• Revaccination – every year

36. Live Attanuated
Vaccine (For Human
seasonal influenza)
• Live attenuated
• Freeze dried
• Diluent – Distilled water
• Single dose
• Intranasal spray
• Revaccination every year

37. CONTRAINDICATION
OF VACCINE
• People with h/o anaphylactic shock
• People with h/o sever reaction to influenza
vaccine
• Who develop Guillain-Barre syndrome
• Children less then 6 month of age
(inactivated influenza vaccine is not
approved)
• People with moderate to sever fever

38. Killed vaccine (For H1N1
Influenza)
• Split virion, Inactivated vaccine
• Route – Intramuscular
• Site of injection – Anterolateral Thigh or Deltoid
region
• Dose: (1/2 dose for Oil adjuvant)
• 0.5 ml for adults and children over 3 years
• 0.25 ml for children from 6 to 3 years
Schedule :
6 months to 9 years – 2 doses one month apart
> 9 years – 1 dose

39. Live Attanuated
Vaccine (For H1N1
influenza)
• Live attenuated
• Freeze dried
• Age – Children above 3
years
• Diluent – Distilled water
• Single dose
• Intranasal spray
• Revaccination every year

40. THANK YOU FOR YOUR
ATTENTION!