This document discusses the epidemiology of tuberculosis. It begins by defining tuberculosis and how it is transmitted. Globally, the mortality and prevalence of TB is highest in India, which accounts for 20% of global cases. Key epidemiological factors that influence the spread of TB are the bacterial agent, host susceptibility, and social determinants. TB is typically transmitted through droplets in the air and has an incubation period of weeks to years. While pulmonary TB is most common, extrapulmonary TB can also occur. Despite prevention and control efforts like BCG vaccination and India's Revised National Tuberculosis Control Programme, TB remains a major public health challenge in India due to ongoing issues with awareness and socioeconomic factors.

1. EPIDEMIOLOGY
OF
TUBERCULOSIS
MS. SAHELI C
LECTURER
IACN

2. INTRODUCTION
 Tuberculosis (TB) - Infectious bacterial
disease caused by Mycobacterium
tuberculosis - most commonly affects the
lungs.
 Transmitted from person to person via
droplets from the throat & lungs of people
with the active respiratory disease.
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3. BURDEN
GLOBALLY :
 In 2013, mortality of TB including HIV was 16 per lakh
cases
 Mortality of TB excluding HIV was 5 per lakh cases
 Prevalence of TB was 159 per lakh
 Incidence of TB was 80 per lakh
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4. INDIA
 India is the highest TB burden country in the world & accounts
for nearly 1/5th (20 per cent) of global burden of tuberculosis,
2/3rd of cases in SEAR.
 Every year approximately 1.8 million persons develop
tuberculosis, of which about 0.8 million are new smear
positive highly'- infectious cases.
 Annual risk of becoming infected with TB is 1.5 % and once
infected there is 10 % life-time risk of developing TB
disease
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6. EPIDEMIOLOGICAL
FACTORS

7. AGENT FACTORS 9/12/201514
 Agent
 Mycobacterium tuberculosis
- facultative intracellular parasite, ingested by phagocytes
& resistant to intracellular killing
 Source of infection
 Human - human case positive for tubercle bacilli & who has
either received no treatment or has not been fully treated
 Bovine - infected milk
 Communicability
 Patients are infective as long as they remain untreated

9. HOST FACTORS
1. AGE: Affects all ages. In India,
0-14 age group – 2%,
15-24 age group - 20%
2. SEX: More prevalent in males
3. HEREDITY: Tuberculosis is not a hereditary disease, but
through studies found that inherited susceptibility is an
important risk factor.
4. NUTRITION: Malnutrition – predisposes to TB
5. Immunity: Man has no inherited immunity against TB
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10. SOCIAL FACTORS
 TB is a social disease with medical aspects, also
known as barometer of social welfare
 Social factors include poor quality of life, poor
housing, overcrowding, population explosion,
undernutrition, lack of education, large families, &
lack of awareness of causes of illness
 All these factors are interrelated & contribute to the
occurrence & spread of TB
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11. MODE OF TRANSMISSION
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 Transmitted mainly by droplet
infection and droplet nuclei – by
sputum-positive patients with
pulmonary TB
 Coughing generates the largest
number of droplets of all sizes
 Frequency & vigour of cough &
the ventilation of the enviroment
influence transmission of infection

13. INCUBATION PERIOD
 Time from receipt of infection to the development of a
positive tuberculin test ranges from 3 to 6 weeks.
 Development of disease depends upon the closeness of
contact, extent of disease & sputum positivity of the source.
Incubation period may be weeks, months or years
RESERVOIR:
Human case is the chief reservoir.

14. TYPES OF TB19
1. Pulmonary :
 In active cases – most commonly involves the lungs (90% cases)
 Symptoms – Chest pain & a prolonged cough
producing sputum
 About 25% of people - asymptomatic
2. Extra pulmonary :
 In 15–20% of active cases, the infection spreads outside the
lungs, causing other kinds of TB
 More commonly in immunosuppressed persons and young
children
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15. Common sites are
 Meninges
 Lymph nodes
 Bones & joints
 Intestine
 Genitourinary tract
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16.  A potentially more serious, widespread form of TB -
"disseminated" TB - commonly known as Miliary
Tuberculosis.
 Miliary TB -10% of extrapulmonary cases
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17. CLINICAL FEATURES
•Coughing that lasts two or more weeks
•Coughing up blood
•Chest pain, or pain with breathing or coughing
•Unexplained weight loss
•Fatigue
•Fever
•Night sweats
•Chills
•Loss of appetite
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33. PREVENTION & CONTROL OF
TUBERCULOSIS
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34. PREVENTION & CONTROL
 Primary prevention-
1. health education & specific protection.
2. Population strategy & high risk strategy
 Secondary prevention- early diagnosis & specific
treatment
 Tertiary prevention- rehabilitation & disability
limitation
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35. BCG-VACCINE
 The first human was vaccinated by the intradermal
technique in 1927
 BCG is the only widely used live bacterial vaccine. It
consists of living bacteria derived from an attenuated
bovine strain of tubercle bacilli
 The WHO has recommended the "Danish 1331" strain
for the production of BCG vaccine
 Since January 1967, the BCG Laboratory at Guindy,
Chennai, has been using the "Danish 1331" strain for
the production of BCG vaccine
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36. CONT..
 There are two types of BCG vaccine - the liquid
(fresh) vaccine and the freeze dried vaccine.
 For vaccination. the usual strength is 0.1 mg 0.1
ml volume. The dose to newborn aged below 4
weeks is 0.05 ml.
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38. RNTCP
 Need for a Revised Strategy.
 India has had an on-going National TB Program, NTP since
1962. Program reviews showed that only 30% of estimated
tuberculosis patients were diagnosed & treated successfully.
 Based on the findings & recommendations of the review in 1992,
the GOI evolved a revised strategy and launched the Revised
National TB Control Programme (RNTCP)in the country.
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39. COMPONENTS OF RNTCP
1. The directly observed treatment short-course
(DOTS) strategy.
2. 'Stop TB Partnership ‘.
both are implemented as a comprehensive
package for TB control.
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49. SUMMARY
 Despite all these national programmes & efforts from govt.
of India , TB still continues to be a major socio- economic
burden of the country
 Still there is need to create awareness among health
care professionals, and the community.
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