SANTOSH KUMAR YADAV (PARA G2) GSVM MEDICAL COLLEGE KANPUR 2015

1. EPIDEMIOLOGY OF
TUBERCULOSIS
SANTOSH KUMAR YADAV
GSVM MEDICAL COLLEGE KANPUR
ROLL NO.- 128
PARA- G2

2. EPIDEMIOLOGY
“The study of the distribution and
determinants of health-related states or
events in specified populations, and the
application of this study to the control of
health problems”
TUBERCULOSIS
Tuberculosis is a specific infectious
disease caused by M. tuberculosis. The
disease primarily affects lungs and causes
pulmonary tuberculosis.

3. TB TRANSMISSION
 TB is spread person to person
through the air via droplet
nuclei
 M. tuberculosis may be
expelled when an infectious
person:
– Coughs
– Sneezes
– Speaks
– Sings
 Transmission occurs when
another person inhales droplet
nuclei

4. TB TRANSMISSION
Transmission is defined as the spread of an
organism, such as M. tuberculosis, from one
person to another.

5. • Probability that TB will be transmitted depends
on:
Infectiousness of person with TB disease
Environment in which exposure occurred
Length of exposure
Virulence (strength) of the tubercle bacilli
• The best way to stop transmission is to:
Isolate infectious persons
Provide effective treatment to infectious
persons as soon as possible

6. INCUBATION PERIOD
• The time from receipt of infection to
the development of a +ve tuberculin
test ranges from 3-6 weeks
• Incubation period may be week, month
or year

7. HISTORY OF TB
• Until mid-1800s, many
believed TB was
hereditary
• 1865 Jean Antoine-
Villemin proved TB
was contagious
• 1882 Robert Koch
discovered M.
tuberculosis, the
bacterium that causes
TB
Mycobacterium tuberculosis
Image credit: Janice Haney Carr

8. TB HISTORY TIMELINE
11999933:: TTBB ccaasseess ddeecclliinnee
dduuee ttoo iinnccrreeaasseedd ffuunnddiinngg
aanndd eennhhaanncceedd TTBB ccoonnttrrooll
eeffffoorrttss
11888844::
FFiirrsstt TTBB
ssaannaattoorriiuumm
eessttaabblliisshheedd
iinn UU..SS..
11886655::
JJeeaann--
AAnnttooiinnee
VViilllleemmiinn
pprroovveedd TTBB iiss
ccoonnttaaggiioouuss
11994433::
SSttrreeppttoommyycciinn
((SSMM)) aa ddrruugg uusseedd
ttoo ttrreeaatt TTBB iiss
ddiissccoovveerreedd
1840 1860 1880 1900 1920 1940 1960 1980 2000
11888822::
RRoobbeerrtt KKoocchh ddiissccoovveerrss
MM.. ttuubbeerrccuulloossiiss
MMiidd--11998800ss::
UUnneexxppeecctteedd rriissee iinn
TTBB ccaasseess
11994433--11995522::
TTwwoo mmoorree ddrruuggss aarree
ddiissccoovveerreedd ttoo ttrreeaatt
TTBB:: IINNHH aanndd PPAASS

10. EPIDEMIOLOGICAL INDICES
• Indices or parameters are needed to
measure the tuberculosis problem in a
community
• For planning and evaluation of control
measures
• Indices are also required for
international comparison

11.  Following epidemiological indices are
generally used in TB :
a) Prevalence of infection:-
 It is the percentage of individual who show a
positive reaction to the standard tuberculin
test.
b) Incidence of infection (Annual infection rate):-
 It is the percentage of population under study
who will be newly infected by M. tuberculosis.
 It reflects the annual risk of being infected in a
given community.

12. c) Prevalence of disease (Case rate) :-
 It is the percentage of individuals who’s
sputum is positive for tubercle bacilli on
microscopic examination.
 It is the best available practical index to
estimate the number of infectious cases
or case load in a community.
d) Indices of new cases :-
 It is the percentage of new tuberculosis
cases per 1000 population occurring
during one year.

13. e) Prevalence of suspect cases :-
 It is based on X- Ray examination of chest.
 Drawback of this index is that radiography
cannot reveal with any certainty.
 That’s why it has no epidemiological
significance.
f) Case detection rate :-
no. of new and relapse cases in a year
estimated incidence of such cases in same year

14. g) Prevalence of new drug resistance
cases :-
 The patients resistance to anti-tuberculosis
drugs.
• Mortality rate :-
 The no. of deaths from TB per lakh
population was used as the index of
the TB problem in a community.
 At present time it has no significance.

15. SOME DEFINATIONS OF TB
CASES
• NEW CASES – A patient with sputum +ve
PTB who has never treated for TB or has
taken anti- tuberculosis drug for less
than 4 week.
• RELAPSE – A patient who return smear
+ve having previously been treated for
TB and cured.
• Return after default- A patient who return
sputum smear +ve after having left
treatment for at least 2 months.

16. • TRANSFER IN- A patient recorded in another
administrative area register and transferred
into another area to continue treatment.
• TRANSFER OUT- A patient who has been
transfer to another area registered and
treatment result are not known.
• CURED– Initially smear +ve positive patient
who completed treatment and had –ve smear
result on at least two occasions.
• COHORT- A group of patients in whom TB
has been diagnosed and who were registered
for treatment during a specified time period.

17. NATURAL HISTORY OF TB
AGENT FACTORS
AGENT
M. TUBERCULOSIS
IS A FACULTATIVE
INTRACELLULAR
PARASITE
SOURCE OF
INFECTION
(TWO SOURCES)
COMMUNICABILITY
PATIENTS ARE REMAIN
INFECTIVE AS LONG
AS THEY REMAIN
UNTREATED
HUMAN SOURCE
MOST COMMON
SOURCE
BOVINE SOURCE
INFECTION USUALLY
BY INFECTED MILK

18. HOST FACTORS
AGE- TB AFFECTS ALL THE AGES
SEX- MORE PREVALENT IN MALES
HERIDITY- TB IS NOT A HERIDITARY
DISEASE
NUTRIENT- MALNUTRITION IS WIDELY
PREDISPOSE TO TB
IMMUNITY- MAN HAS NO INHERITED
IMMUNITY AGAINST TB

19. SOCIAL FACTORS
POOR QUALITY OF LIFE
POOR HOUSING
OVERCROWDING
POPULATION EXPLOSION
UNDERNUTRITION
LACK OF EDUCATION
LARGE FAMILIES
EARLY MARRIAGES etc.

20. GLOBAL BURDEN OF TB
• 2 billion infected, i.e. 1 in 3 of global population
• 9.4 million (139/lakh) new cases in 2008, 80% in
22 high-burden countries
• About 5.7 million cases were notified through
DOTS programme during 2010
• Global incidence of TB has peaked in 2004 and is
declining
• 1.77 million deaths in 2007, 98% in low-income
countries
• 1.4 million deaths in 2010
• MDR-TB -prevalence in new cases around 3.6%

21. GLOBAL SITUATION
• Since 1995, over 21 million patients have
been diagnosed and treated in DOTS
programmes.
• In 2007, 5.5 million new and relapse TB
cases were initiated on treatment under
DOTS strategy.
• Of 2.5 million new smear positive patients
registered in 2006, 85% were successfully
treated under DOTS.

22. TUBERCULOSIS IN INDIA
• Estimated incidence
1.96 million new cases annually
0.8 million new smear positive cases annually
75 new smear positive PTB cases/lakh population per
year
• Estimated prevalence of TB disease
3.8 million bacillary cases in 2000
1.7 million new smear positive cases in 2000
• Estimated mortality
330,000 deaths due to TB each year
Over 1000 deaths a day
2 deaths every 3 minutes

23. • Prevalence of TB infection
40% (~400 million) infected with M.
tuberculosis (with a 10% lifetime risk of TB
disease in the absence of HIV)
• Estimated Multi-drug resistant TB
< 3% in new cases
12% in re-treatment cases
• TB-HIV
~2.31 million people living with HIV
(PLWHA)
10-15% annual risk (60% lifetime risk) of
developing active TB disease in PLWHA
About 80% of TB patients are between 15-54
year of age, while two- third of the cases are
male.

24. India is the highest TB burden country accounting
for more than one-fifth of the global incidence
Indonesia
6%
Nigeria
5%
Other countries
20%
Other 13 HBCs
16% China
14%
South Africa
5%
Bangladesh
4%
Global annual incidence = 9.4 million
India annual incidence = 1.96 million
Phillipines
Pakistan
3%
Ethiopia
3%
3%
India
21%
India is 17th among 22
High Burden
Countries (in terms of
TB incidence rate)
Source: WHO Geneva; WHO Report 2009: Global Tuberculosis Control; Surveillance, Planning and Financing

25. MCQ’S
1. National tuberculosis institute is
located at:
A. New Delhi
B. Chingelput
C. Bangalore
D. Chennai

26. 2. Decrease in which of the following
parameters indicate the decrease in
tuberculosis problem in India ?
A. Incidence of infection
B. Prevalence of infection
C. Incidence of disease
D. Prevalence of disease

27. 3. Mycobacterium tuberculosis infection
in humans is most because of :
A. Contact
B. Inhalation
C. Infiltration
D. Inoculation

28. 4. By WHO best criteria for TB diagnosis
is ?
A. Sputum +ve
B. Chest pain
C. Cough- 3 weeks
D. X-ray finding

29. 5. The number of sputum +ve cases of TB
per lakh in India is ?
A. 75
B. 50
C. 40
D. 10

30. 6. Which of the following is not false
about the annual risk of TB ?
A. ARI of 1%= 75 new cases
B. Current ARI in India is 1.7%
C. It represents new cases of TB
D. It is assessed by tuberculin conversion
in previously non-vaccinated children

31. REFRENCES
• Internet and Wikipedia
• K. Park
• Vivek Jain