Influenza, caused by viruses primarily affecting the respiratory tract, led to significant mortality during past pandemics, with notable statistics from India in 2019 showing a death rate of 4.2% from H1N1 cases. Prevention focuses on vaccination, particularly for high-risk groups, and antiviral treatments, including neuraminidase inhibitors, have been developed for both adults and children. Transmission occurs via droplets from infected individuals, highlighting the importance of controlling environmental factors and promoting hygiene practices to mitigate spread.

1. INFLUENZA
-BY ANKITA MITRA ( 2ND BSC)

2. INTRODUCTION
 During 1918 influenza pandemic, 12 to 13
million people died in India. Influenza is
caused by a virus that attacks mainly the
upper respiratory track that include the nose,
throat and bronchi and rarely the lungs. In
India there were 28,798 H1N1 cases, 1218
deaths which equality the death rate 4.2%
(2019, National centre for disease control)

3. DEFINITION
WHO : Influenza is a viral infection that affects mainly
the nose throat bronchi and occasionally lungs.
Infection usually lasts for about a week and is
characterized by sudden onset of high fever, aching
muscles, headache and severe mailise, non-productive
cough, sore throat and rhinitis

5. EPIDEMIOLOGICAL TRIAD

6. CAUSATIVE AGENT OF INFLUENZA
Influenza virus belongs to the family of
orthomixoviridae.
There are three viral subtypes:
* Influenza type A, type B, and type C. Influenza A has
2 subtype which are important for humans:
A(H3N2) and A(H1N1) of which the former is currently
associated with most deaths.

7. * Influenza viruses are defined by two different protein
components, known as antigens on the surface of the
virus. They are spike like features all Hemagglutin (H)
and Neuraminidase (N) components. H antigen initiats
infection and the N antigen releases the virus from
infected cell.

8. • Birds and animals are considered as the major reservoirs.
• Usually the source of infection is the case or subclinical case.
• Virus is present in the nesopharynx of infected person.
• Period of infectivity is 1 to 2 days before and 1 to 2 day after the
onset symptoms.

9. HOST FACTORS OF INFLUENZA
• Effects all ages and both sexes
• Highest mortality is found among old people over
65 years, children below 18 months and people with
chronic disease like diabetes.
• Human mobility is major cause of spread of
infection.

10. ENVIRONMENTAL FACTORS OF
INFLUENZA
* SEASONAL : Epidemics takes place in winter in Northern
hemisphere and in rainy season in Southern hemisphere.
* Overcrowding facilitate transmission.

11. MODE OF TRANSMISSION
• The virus spread from person to person through
droplet infection or droplet nuclei by sneezing,
coughing and talking.
• * Portal of entry : the influenza virus enters the body
through the nose and the throat.

12. INCUBATION PERIOD OF THE VIRUS
 18 to 72 hours.

13. CLINICAL FEATURES OF INFLUENZA
 Fever
 Headache
 Cough
 Sore throat
 General mailise

14. COMPLICATION
 Bacterial pneumonia
 Ear infection
 Dehydration
 Myocarditis
 Even heart attack occurs as a complication of
influenza

15. PREVENTION
 Vaccination is the prime measure for preventing influencer and bringing
down the impact of epidemics. They are different types of influence a
vaccines available and in existence for more than 60 years.
 It is recommended that elderly person, and the persons of any age who
are considered at “high risk” for influenza related complications due to
underlying health conditions should be vaccinated.
 WHO recommended annually a vaccine that targets the 3 most virulent
strains in circulation.

16. KILLED VACCINE
 One dose of vaccine contains 15 microorganism of HA.
 A single dose of 0.5 ml is given to adults and childrens over 3 years.
 0.25 ml is given for children between 6 to 36 months.
 A single dose of inactivated vaccine annually is appropriate, except for
previously unvaccinated preschool children pre existing with medical
condition who should receive 2 doses at least one month apart.

17. LIVE ATTENUATED VACCINE
 Widely used in USSR.
 Administered as nasal drops.

18. ANTIVIRAL DRUGS
• Antiviral drugs such as the M2 inhibitors (acting against type type A virus)
and the more recently developed neuraminidase inhibitors (acting against
both type A and B viruses) have been shown to be effective for treatment (
and for some agents, prophylaxis) and are now available in many
industrialized countries.
* Presently Amantadine and rimantidine are not recommended for anti-viral
treatment or chemoprophylaxis of influenza A because of resistance in
circulating influenza A strains.

19. ANTI-VIRAL DRUGS FOR ADULTS
 Inhaled zanamivir is recommended for treatment of adults
with uncompleted acute illness of influenza A or B virus, and
for chemoprophylaxis of influenza among adults.
 Zanamivir is not advised to people with respiratory disease
like asthma or chronic obstruction pulmonary disease
(COPD).

20.  Zaiamivir is given using inhaler device. This is administered as
5mg blister dosage per inhalation. The recommended dosage
for influenza is 2 inhalation (10 mg) twice daily 1-2 hours
apart.
 For chemoprophylaxis zanamivir 10 mg is administered (2
inhalation) once a day.

21. ANTI-VIRUS DRUGS FOR CHILDREN
 Zanamivir is recommended to treat influenza among children aged 7
years and older. Duration of treatment is 5 days.
 Zanamivir is approved for chemoprophylaxis of influenza among children
aged 5 years and older.
 Treatment and chemopraphylaxis dosing and frequency at the same for
children as for adults

22. CONTROL MEASURES FOR
INFLUENZA
 Adequate ventilation required in living rooms.
 Avoid overcrowded places during epidemics.
 Stay at home at the first sign of influenza.
 Infected person should cover the mouth and nose with
handkerchief to protect others from infection.

23. CONCLUSION
 Influenza virus cause the flu. Influenza viruses are spread
from person to person by coughing and sneezing. Influenza
viruses occurs naturally in birds , but can sometimes be
transmitted to humans and other animals. The highly
pathogenic Avian influenza viruses can be very dangerous to
poultry and humans.