Influenza its epidemiological determinants, controlling, prevention, and diagnotic measures

1. Influenza
MOHAN BASTOLA
BPH 4TH SEMESTER
ROLL NO: 18
EDENBURGH INTERNATIONAL COLLEGE

2. Introduction:
 Influenza is an acute respiratory disease characterized by fever,
headache, myalgia, lethargy, coryza (bacterial infection in the upper
respiratory mucous membrane), sore throat and cough caused by
influenza virus.
 Infections in children, particularly type A and B (H1N1) may also be
associated with gastrointestinal symptoms such as nausea, vomiting and
diarrhea.

3. Contd…
 A rapid epidemic nature and cause ill to many persons in a short period.
 Complication leads to Pneumonia. It affects seriously to older aged
people and to the people who are suffering with heart, kidneys, lungs
and anemic diseases which can kill to the persons with lower immune
defense.
 The disease can be observed in the form of sporadic, epidemic and
pandemic.

4. Epidemiological determinants:
Agent factor:
 Influenza virus (types A, B and C) is the causative agent. Type A and B
are mainly responsible for epidemic, while type C causes sporadic type
of transmission.
Reservoir:
 Man is the major reservoir of the viruses, however infection also occur
among other mammals and birds. Influenza occurring in birds are avian
influenza also called Bird’s flue.

5. Source of infection:
 During epidemics, a large number of mild and asymptomatic infection occurs,
which play an important role in the spread of infection. The secretion of the
respiratory tract are infective.
Period of infectivity:
 Virus is present in the nasopharynx from 1 to 2 days before and 1 to 2 days after
onset of symptoms.

6. Host factors:
Age and Sex:
 Affects all ages and both sexes. In general, the attack rate is lower among adults.
Children constitute an important link in the transmission chain. The highest mortality
rate during an epidemic occurs among certain high-risk groups in the population
such as old people(generally over 65 years of age), children under 18 months, and
persons with diabetes or chronic heart diseases, kidney and respiratory ailments.

7. Environmental factors:
Season:
 Outbreak can be observed in any season however, out breaks in winter in
mountainous region and in rainy season in the Terai region are frequently
observed.
Overcrowding:
 Rate are high in close population groups, e.g., school, institution etc.

8. Mode of transmission:
 Transmitted by airborne spread in aerosols but can also be transferred by direct
contact with droplets.
 Nasal inoculation after hand contamination with the virus is also an important
mode of transmission.
 Direct contact is important, as the virus will survive some hours in dried mucus
particularly in cold and dry environments. Among the houses in which group
of people live together are the risk groups like army camp, students hostel, and
theatres.

9. Incubation period:
 Incubation period is 24 to 72 hours.

10. Signs and symptoms:
 Common symptoms of influenza may include: Fever and chills, cough, nasal
congestion; body aches, especially joints and throat, fatigue headache,
irritated, watering eyes, reddened eyes, skin (especially face), mouth, throat and
nose and in children, croup (laryngotracheobronchitis) and gastrointestinal
symptoms such as diarrhea and abdominal pain

11. Diagnosis:
 Culture or antigen testing of appropriate respiratory specimens such as
nasopharyngeal aspirate or nose and throat swabs, taken within five days of
onset.
 By serology performed on blood specimens taken during the acute and
convalescent stages. The diagnosis can be confirmed in the laboratory by one or
more of the following:
 detection of influenza virus by culture or nucleic acid testing, most commonly
polymerase chain reaction (PCR) testing
 demonstration of a significant rise in the influenza-specific antibody.

12. Treatment:
 Plenty of rest and liquids.
 Avoid using alcohol and tobacco. Give acetaminophen (paracetamol) to
relieve the fever and muscle aches.
 The two classes of antiviral drugs used against influenza are neuraminidase
inhibitors (e.g. oseltamivir, zanamivir)and M2 protein inhibitors (adamantane
and remantadne derivatives).

13. Prevention:
 Personal hygiene, protection from ingestion of droplets by covering the
nose and mouth can prevent from transmitting the disease. Public
awareness through proper health education especially during epidemics
is the major activities to prevent the transmission.

14. Controlling measures:
 The disease can be controlled three basic principles like preventive
measures, control of the patient and epidemic measures:
1.Preventive measures:
 Vaccination program but in Nepal the vaccination program has not
been launched. Healthy behaviors are the best for prevention.

15. Contd.......
2.Control of patient:
 Report to health authority and isolation of the patient. Treatment by
antibiotics is of no use for influenza.

16. Contd..........
3.Epidemic measures:
 Public health surveillance (search for suspected cases in the affected
area and control the patient) will be the first step. Close the schools if
affected among school going children. Strong health education through
mass media to the students and general public be made for prevention.

17. Reference:
 K.Park’s Textbook of Preventive and Social Medicine(24th edition)

18. THANKYOU.