KARAGANDA STATE MEDICAL KARAGANDA STATE MEDICAL UNIVERSITYUNIVERSITY

SUBJECT-EPIDEMIOLOGY SUBJECT-EPIDEMIOLOGY

SIWTSIWT

SUBMITTED TO: AISULUKAMAROVA SUBMITTED BY: MANOJ

KUMAROM PRAKASH

GROUP- 3009

EPIDEMIOLOGYEPIDEMIOLOGY OFOF TUBERCULOSISTUBERCULOSIS

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.

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

TB TRANSMISSIONTB TRANSMISSION

TB TRANSMISSIONTB TRANSMISSION

Transmission is defined as the spread of an organism, such as M. tuberculosis,

from one person to another.

Probability that TB will be transmitted depends on:Infectiousness of person with TB diseaseEnvironment in which exposure occurredLength of exposureVirulence (strength) of the tubercle bacilli

The best way to stop transmission is to:Isolate infectious personsProvide effective treatment to infectious persons as soon as possible

INCUBATION PERIODINCUBATION PERIODThe 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

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

HISTORY OF TBHISTORY OF TB

Mycobacterium tuberculosisImage credit: Janice Haney Carr

1840 19201860 1900 1940 1960 1980 20001880

1993: TB cases decline 1993: TB cases decline due to increased funding due to increased funding and enhanced TB control and enhanced TB control

effortsefforts1884: 1884:

First TB First TB sanatorium sanatorium established established

in U.S.in U.S.

1865: 1865: Jean-Jean-

Antoine Antoine Villemin Villemin

proved TB is proved TB is contagiouscontagious

1943: 1943: Streptomycin Streptomycin

(SM) a drug used (SM) a drug used to treat TB is to treat TB is discovereddiscovered

1882: 1882: Robert Koch discoversRobert Koch discovers

M. tuberculosisM. tuberculosis

Mid-1980s: Mid-1980s: Unexpected rise in Unexpected rise in

TB casesTB cases

1943-1952: 1943-1952: Two more drugs are Two more drugs are discovered to treat discovered to treat TB: INH and PASTB: INH and PAS

TB HISTORY TIMELINETB HISTORY TIMELINE

EPIDEMIOLOGICAL EPIDEMIOLOGICAL INDICESINDICESIndices 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

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.

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.

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

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.

SOME DEFINATIONS OF TB SOME DEFINATIONS OF TB CASESCASESNEW 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.

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.

NATURAL HISTORY OF NATURAL HISTORY OF TBTB

AGENT FACTORS

AGENTM. TUBERCULOSISIS A FACULTATIVEINTRACELLULAR

PARASITE

SOURCE OF INFECTION

(TWO SOURCES)

COMMUNICABILITYPATIENTS ARE REMAIN INFECTIVE AS LONG

AS THEY REMAIN UNTREATED

HUMAN SOURCEMOST COMMON

SOURCE

BOVINE SOURCEINFECTION USUALLY BY INFECTED MILK

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

SOCIAL FACTORS

POOR QUALITY OF LIFE

POOR HOUSING

OVERCROWDING

POPULATION EXPLOSION

UNDERNUTRITION

LACK OF EDUCATION

LARGE FAMILIES

EARLY MARRIAGES etc.

GLOBAL BURDEN OF TB GLOBAL BURDEN OF TB 2 billion infected, i.e. 1 in 3 of global

population9.4 million (139/lakh) new cases in 2008,

80% in 22 high-burden countries About 5.7 million cases were notified

through DOTS programme during 2010Global incidence of TB has peaked in

2004 and is declining1.77 million deaths in 2007, 98% in low-

income countries1.4 million deaths in 2010MDR-TB -prevalence in new cases around

3.6%

GLOBAL SITUATIONGLOBAL SITUATIONSince 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.

TUBERCULOSIS IN INDIATUBERCULOSIS IN INDIAEstimated incidence

1.96 million new cases annually0.8 million new smear positive cases annually75 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 mortality330,000 deaths due to TB each yearOver 1000 deaths a day2 deaths every 3 minutes

Prevalence of TB infection40% (~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 cases12% 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.

India is the highest TB burden country India is the highest TB burden country accounting for more than one-fifth of the accounting for more than one-fifth of the global incidence global incidence

Indonesia6%

Nigeria5%

Other countries20%

Other 13 HBCs16% China

14%

South Africa5%

Bangladesh4%

Ethiopia3%

Pakistan3%

Phillipines3%

India21%

Source: WHO Geneva; WHO Report 2009: Global Tuberculosis Control; Surveillance, Planning and Financing

Global annual incidence = 9.4 million

India annual incidence = 1.96 million

India is 17th among 22 High Burden

Countries (in terms of TB incidence rate)

REFRENCESREFRENCES

Internet and WikipediaK. ParkVivek Jain