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					Epidemiology of TB
  and its control



  Dr. V. K. Chadha
  Sr. Epidemiologist
 National TB Institute
      Bangalore
I. General concepts in TB Epidemiology

II. Epidemiological indicators of TB and their estimation

III. Global epidemiological trends of TB

IV. TB situation in South East Asia

      - presentations by Country participants

V. Prospects of TB control
Why do we need to study
 Epidemiology of TB?
           Aims of Epidemiology ?

•   To describe natural history of disease
•   Describe Distribution and relative importance
•   Measure frequency
•   To define risk groups
•   To evaluate interventions
•   To describe trends
•   To predict future trends and changes in disease
    presentation.
          What is Epidemiology ?
Epi - among ;    Demos - People ;       Logos - Study
DEFINITION
Epidemiology is the study of the -
• Frequency
• Distribution - time, place & person
• Determinants - physical, biological, social,
  behavioural & cultural
of health problems & health related events and
  application of this study to control health
  problems.
                     A Model for the Epidemiology of Tuberculosis



 Risk                   Risk                    Risk                         Risk
factors                factors                 factors                      factors

                                                           Infectious
                                                          tuberculosis
                                 Subclinical
          Exposure                infection                                               Death

                                                         Non-infectious
                                                          tuberculosis



                                                                   Rieder HL. Infection 1995;23:1-4
          Risk of exposure ?
* Incidence / prevalence of infectious TB in
  the community

* Duration of infectiousness

* opportunities for case - contact interactions
     -Urban/Rural
     -No. of individuals in the house holds
       Risk of Infection ?
* No. of infectious droplets produced

* Volume of shared air space

* Length of exposure

* Ventilation

* Climatic conditions
                         Tuberculous Infection Among Children by Type of
                          Contact and Bacteriologic Status of Index Case,
                         British Columbia and Saskatchewan, 1966 - 1971

                    40
                              Close
                    35
                    30
Per cent infected




                    25
                    20
                    15
                                       Casual                Close
                    10
                     5                                                Casual
                     0
                                Smear +                         Smear -
                              Grzybowski S, et al. Bull Int Union Tuberc 1975;50:90-106
  Household transmission of TB
   - important epidemiological factor
• Case control study in Malawi
                     TB among contacts

   Cases     770   56/2766
                              P<0.001
   Controls 918    11/3203
         Each case leads to two cases

          -_-_-



 1 Infectious case



                               20 contacts
                     2 cases
                      of TB
1 Non-infectious
Risk of Infection Among Contacts as a Function of the Proximity of Contact
What is the most important risk
        factor for TB?
                                      Example of Risk Differences in Individuals
                                      Following Infection with M. tuberculosis
Cases per 1,000 person-years   1000                                                  ??



                                100
         (log scale)




                                 10




                                  1
                                         Long-standing    Recent        Super-     Underlying
                                           infection     infection     imposed HIV infection
                                                                     HIV infection
Risk factors for disease given that infection has
                   occurred ?

Risk factor         Relative Risk
AIDS                     200
HIV Infection           30-40
                                    [Relative Risk of
Silicosis                30         remotely acquired
                                    infection = 1]
Recent Infection         20         (0.2% per year)
Under-nutrition          2-5
Diabetes mellitus        2-5
Incidence of TB in South Africa per 1000 population


   30

   25

   20
                                     General population
   15
                                     Gold miners
   10

    5

    0

                                 IJTLD,3(9),1999,791-798
    Other High Risk Groups
 Populations in war / civil unrest
 Refugees and migrants
 Slum dwellers
 Homeless people/Foot path dwellers
 Smoking
 Prisoners
               TB in prisons
Studies in Thailand
* TB incidence 90 times higher in prisons
* High HIV sero-positivity in TB cases
* High levels of drug resistance
• RFLP studies signify role of recent transmission
         Determinants of death?

*   Severity of illness
*   Smear positivity
*   delay in diagnosis
*   quality of treatment
*   drug susceptibility pattern
Epidemiological indicators of TB and
          their estimation
  Enumerate epidemiological
indicators of TB you know of?
Epidemiological indicators of tuberculosis ?


* Prevalence of infection
* Incidence (average annual risk) of infection
  (ARI)
* Prevalence of disease
* Incidence of disease
* Tuberculosis mortality rates
How to estimate prevalence of
         infection?
      Estimating prevalence of infection

* Study population-sampling

* Registration of eligible age group

      - house-to-house / school based.

* Informed consent.

* Examination for BCG scar.

* Tuberculin testing with 1TU/2TU PPD RT23 with tween 80.

* Reading of reaction sizes appx. 72 hours later.
 What is the rationale behind tuberculin
          surveys in children ?

• Extent or recent transmission

• Study trends in TB epidemiology
  (Ultimate aim of control programme is to
  replace older more infected cohorts with
  younger less infected cohorts)
      Analysis of tuberculin survey
ction size   % of       Reaction size % of
             children                 children
  1 mm                     16 mm
  2 mm                     17 mm
  3 mm                     18 mm
  4 mm                     19 mm
  5 mm                     20 mm
  6 mm                     21 mm
  7 mm                     22 mm
  8 mm                     23 mm
  9 mm                     24 mm
  10 mm                    25 mm
  11 mm                    26 mm
  12 mm                    27 mm
  13 mm                    28 mm
  14 mm                    29 mm
  15 mm                    30 mm
                               Frequency Distribution of Tuberculin Skin
                                   Test Reaction Sizes, Korea 1975

                    0.15
Fraction reacting




                    0.10



                    0.05



                    0.00
                           0       5      10         15         20        25        30

                                               Induration (mm)
                                               Korean Institute of Tuberculosis 1976:1-116
                                  Frequency distribution of tuberculin reaction
                                   sizes among children aged 1-9 years - Kota
             40


             35

                                                                                                     N = 3870
             30


             25
Percentage




             20


             15


             10


             5


             0
                  1   2   3   4   5   6   7   8   9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34

                                                               Reaction in mm
Estimation of incidence of
        infection?
Dual skin testing at two different periods
   -Conversion
   -Boosting


Compute average annual risk of infection
(ARTI) = 1-(1-P)1/A
                     A RT I


• Key epidemiological indicator in developing
  countries.
• It is the probability of acquiring new
  tuberculosis infection or re-infection over the
  course of one year.
A R I expresses the overall impact of various
  factors influencing the transmission of tubercle
  bacilli !


     - Load of infectious cases

     - Efficiency of case finding

     - Efficiency of treatment programme
ARI identifies the regions of high transmission
It provides an indirect estimate of size of sources
  of infection
Any change in disease burden and programme
  implementation is first reflected in the change in
  ARI
It holds the key to the study of epidemiological
  trends which are more important than exact
  estimates of disease prevalence
How to estimate prevalence of
          disease?
   DISEASE SURVEY METHODOLOGY

 Sampling of representative population
 House to house registration
 Screening:
   - MMR X-ray of all above five years of age
   - Symptomatic screening
 X-ray pictures read by two independent readers and by an
   umpire reader
 Sputum specimens (2/3) collected from persons with abnormal
   X-ray shadows & / or chest symptomatics
 Sputum examination by direct microscopy (and culture).
How to estimate disease incidence?
Relationship between ARTI and
      incidence of disease
Styblo derived the following relationship
from data of pre- chemotherapy

 • Every one percent of ARTI corresponds to
   50 new smear positive cases per 100,000
   population per year
Relationship between ARI & Incidence of smear
   positive cases of Pulmonary Tuberculosis
                (Indian studies)
                         Incidence / 100,000
                          pop for every one
                           percent of ARI

  NTI Longitudinal
                                53
  study (1961 – 1968)


  BCG Prevention Trial       42-74 (57)
 Relation between ARI and Incidence !


* Situation : Disease incidence remains same
 but the risk of infection declines
     Q 1. When is this situation likely?
     Q 2. What is the impact on equation
         (relationship) ?
What happens to the equation in
      high HIV settings?
The equation is dependent more on
number of infections generated per
 case and not merely on incidence
      Disease mortality rates !

* Community based prospective studies

* Death certification
ESTIMATION OF ANNUAL RISK OF
 TUBERCULOUS INFECTION IN
  DIFFERENT ZONES OF INDIA
     -A CROSS SECTIONAL STUDY

             2000-2003
Districts selected for National Sample Survey -ARI
The proportion of children with BCG scar by zone


           North Zone     45.3%
           South Zone     64.3%
           West Zone      52.0%
           East Zone      51.5%
The estimated prevalence of infection and ARTI by zone

                     Prevalence
            Zone                       ARTI
                    of infection


                       10.3%           1.9%
            North
                     (8.4-12.2)       (1.5-2.2)
                        9.3%           1.8%
            West
                     (6.8-11.8)       (1.3-2.3)
                        6.1%           1.1%
            South
                      (4.9-7.2)       (0.9-1.3)
                        6.9%           1.3%
             East
                      (5.5-8.2)       (1.0-1.6)


                     ( ) : 95% C.I.
          Prevalence of infecton by zone and stratum (1-9 years)

16
              14.1
14                          Rural     Urban      Zone
                                                         12.6
12
                     10.3
                                     9.8
10      9.1                                                     9.3         9.0
                                                   7.8
%




    8                                                                              6.9
                                                                      6.5
                                           6.1
    6
                               4.5
    4

    2

    0
              North                  South               West               East
Does higher ARTI in urban areas
  indicate higher incidence of
      smear positive cases
                     Programme inputs
   The survey findings provide baseline estimates of ARI for
        -       evaluation of TB Control Measures.
        -       Study of epidemiological trends in years to
                come
   High rate of ARI indicates high load of infectious cases of TB in
    most parts of India. Prolonged and sustained efforts required to
    control TB.
   There are significant inter-regional differences in tuberculosis
    situation.
   Intensification of TB control services in urban areas with
    higher ARI rates to be taken up on priority basis.
   Case finding expectations cannot be applied uniformly all over
    the country
     Other Epidemiological indicators of
               Tuberculosis

* Ratio of prevalence and incidence
* Age distribution of cases
* Case fatality rates
* Force of MDR cases
* TBM notification rates
* Disability adjusted life years (DALY)
Epidemiological trends of TB
                              Tuberculosis Mortality in Three European Cities,
                                Modeled From Available Data, 1750 - 1950

                     1000
                            London   Stockholm
Deaths per 100,000


                      800                        Hamburg


                      600


                      400


                      200


                        0
                             1750        1800         1850          1900         1950

                                                      Year
                                       Grigg ERN. Am Rev Tuberc Pulm Dis 1958;78:151-72
                           Tuberculosis Mortality Rates in Germany, 1892 - 1940

                     250
Deaths per 100,000
                     200

                     150

                     100

                     50

                       0
                              1890      1900        1910          1920      1930        1940

                                                           Year
                       Redeker F. In: Handbuch der Tuberkulose (Hein J, et al, eds) 1958;1:473
                                               Secular Trend in Annual Risk of Infection,
                                                    Selected European Countries
                                     Engl
                                         and
                                               and
                                                   W   ales         Serbia
                               10                                               Poland
                                                                       Slo
                                                                           ven
                                                                               ia
Per cent risk (log scale)




                                            Slope reference:                         No
                                            % decline / year                            rw
                                                                                          ay
                                 1                             0%
                                                              5%                                          Fr
                                                                                                            an
                                                                                                               ce
                                                              10%                       Ne
                                                                                           th
                               0.1                                                            erla
                                                              15%                                  nd
                                                                                                      s


                             0.01

                                     1900               1920              1940              1960                    1980

                                                                        Calendar year
                            Waaler H, et al. Bull Int Union Tuberc 1975;50:5-61                  Sutherland I, et al. Tubercle 1983;64:241-253
                            Sutherland I, et al. Bull Int Union Tuberc 1971;45:75-114      Styblo K, et al. Bull Int Union Tuberc 1969;42:5-104
                            Lotte A, et al. Int J Epidemiol 1973;2:265-82                Vynnycky E, et al. Int J Tuber Lung Dis 1997;1:389-96
     TB trends in Europe
        Median age in Finland
70                        65.1
60          55.7

50
     39.4
40                               1954
                   31.1
30                               1986

20
10
0
      Males        Females
       TB trends in Europe
           Netherlands

Year      ARI      Median Age

1950      0.53%    28.9 year
1980      0.21%    43.7 year
   Global drug resistance surveillance

             D.R. among new   D.R. among
             cases            previously treated
                              cases
1994-96      1.4%             13%



1996-99      1.0%             9.3%
                                 Reported Tuberculosis Cases in the United States, 1953 - 1997

                               80000
 Number of cases (log scale)




                               40000




                               20000



                                       1950    1960      1970        1980      1990   2000

                                                        Year of notification
Centers for Disease Control and Prevention. Reported Tuberculosis in the United States 1996:1997:5
                                Centers for Disease Control and Prevention. MMWR 1998;47:253-7
                                   Annual Risk of Tuberculous Infection
                                     WHO South-East Asia Region


                         5



                         2
Risk of infection (%)
     (log scale)




                         1
                              Slope reference:
                              % decline / year
                        0.5                      1%

                                                 5%           India
                        0.2                                   Indonesia
                                                 10%
                                                              Thailand

                        0.1


                                 50               60          70          80

                                                       Year
                                  Cauthen GM. WHO Document 1988;WHO/TB/88.154:1-34
             Trends in ARI-
               Chingleput


 At intake in 1969           :   1.8%
 After 4 years in 1973       :   1.8%
 After 10 years              :   1.9%
 After 15 years              :   1.7%
How does HIV pandemic
 influence TB epidemic
• Higher rate of progression from latent infection
  to disease (5-10% per year compared to 10% per
  year among HIV negative)

• Previously HIV infected persons when exposed
  to TB rapidly develop the disease.

• Excess cases due to the above lead to increased
  transmission of infection

• Higher case fatality due to HIV infection
    Evidence of association between
             HIV and TB
* Increase in TB in areas worst affected by HIV
* Higher increase in age group affected by HIV.
* 50 to 70% AIDS cases develop TB in SEAR.
* HIV positivity higher among TB cases than
  general population.
   -Northern Thailand: HIV positivity in TB cases :
  40%
                   : Malawi : 75%
Determinants for the Frequency of HIV-Associated Tuberculosis in a Community



       Total population



                                                         Prevalence of infection with
              Infected with                              M. tuberculosis
              M. tuberculosis
                                                         Prevalence and incidence
                                                         of HIV infection

                                                         Overlap of the two respective
                                                         population segments

                          Infected with HIV
                                 Impact of HIV Infection on Tuberculosis Notifications
                                        in Chiang Rai, Thailand, 1985 - 1994
                           500
No. of cases (log scale)
                                                                                    All cases
                           400



                           300

                                                                                    HIV-neg cases


                           200


                                  85                     90                        95

                                                   Year of notification

                                                               Yanai H, et al. AIDS 1996;10:527-31
                                            TB trends in Africa
                                       (countries with high HIV rates)
                                 350
Standardized notification rate




                                 300
                                 250
                                 200
                                 150
                                 100
                                  50
                                   0
                                   1980     1985     1990    1995    2000
                                      Estimated TB incidence vs
                                           HIV prevalence
                          800
Estim ated TB incidence




                          600
    (per 100K, 1999)




                          400


                          200


                           0
                                0.0       0.1          0.2            0.3    0.4
                                        HIV prevalence, adults 15-49 years
Notification Rates of Sputum Smear-Positive Tuberculosis,
        by Age, Tanzania Mainland, 1984 and 1995
Notifications per 100,000   200                    1995


                            150


                            100
                                                            1984

                             50


                              0
                                  0   15      25    35    45    55    65

                                                     Age group (years)

                                           Tanzania NTLP / IUATLD. Progress Report 1996;No. 36
                      TB morbidity rates in Russia

                90
                80
                70
per lakh pop.



                60
                50
                40
                30
                20
                10
                 0
                     1970 1980 1990 1997 1998 1999


20% of all patients in Russia have MBR TB
                 Case fatality rates in Russia
  35
  30
  25
  20
% 15
  10
   5
   0
               1987                        1997

Increase in CFR attributable to increase in drug resistance cases
           Culture Positive cases, Prevalence:Incidence
                            - Chingleput
                                                                4.5


                                                                3
                                 Average - 3.4
                                 (3.6 for smear pos)
                                                                1.5


                                                                 0
1968-70   1971-73      1973-75      1976-78       1979-81   1981-83
In your opinion, what should be the
practical methods of monitoring
epidemiological trends in any given
community
                    Global picture

• 3rd largest cause of death (2.8%) and loss of DALYs in
  15-59 year age group
• Incidence all cases - 8.8 million (2002)-141/100000
• in 22 HBCs - 7.0 million (80%)
• Smear + - 3.9 (63/100000) million
• Case notifications of smear positive cases increasing @
  4% per year- 5% in eastern Europe and 7% in high HIV
  African countries.
Epidemiological situation of TB
 in South East Asian countries
      Format for Country presentations
Estimated incidence of New smear
positive cases
Latest estimates of ARTI

Population mortality rates

Any information on disease trends

HIV sero-prevalence among TB
cases
MDR in new cases

MDR in previosly treated cases

Any other epidemiological
information eg, age sex distribution
of cases, TB in prisoners etc.
                 TB in South-East Asia

      EUR AMR
  EMR 6%   5%
   8%
                           SEAR
AFR                         38%
18%


                                    Incidence: 3 mill
                                    Deaths : 1 mill (1500/day)
      WPR
      25%

      India, Bangladesh, Indonesia, Myanmar & Thailand
      contribute 95% of regional burden
                  HIV-TB in SEAR

* Second largest number of HIV positives after SSA
      SSA:60%                 SEAR:30%
* 6 million HIV positives in SEAR
      India           :4 mill
      Thailand        :1 mill
      Myanmar         :0.5 mill
* Low sero-positivity in Bangladesh, Maldives, Bhutan,
  Indonesia and Sri lanka
* Nepal : Low in antenatal women, high among IDUs.
TB situation in India
Prevalence of sputum positive pulmonary TB
       Area                   Year      Preval. Rate
                                        per 1000 pop.
   National Sample Survey   1955-58          4

   Tumkur                   1960-61        4.1
                            1979           4.4
   Rural Bangalore          1960-61        4.1
                            1967-68        3.9
                            1974-75        3.2
                            1984-86        4.4
   Chingleput               1968-71        10.7
                            1973-75        8.9
                            1979-81        7.7
                            1984-86        6.9
                            1999-2001      6.9
   Raichur                  1988-89        10.7
   Morena, M.P.             1991-94        12.7
                                Annual Risk of Infection (%)




                                0
                                       0.5
                                              1
                                                    1.5
                                                           2
                                                               2.5
                                                                     3
                                                                         3.5
                                                                               4

       TumkurDistt,1960-61

       TumkurDistt,1972-73

       Rural Bangalore, 1961

       Rural Bangalore, 1970

  Bangalore(Rural), 1977-78

       Bangalore Rural, 1984

Peri urban Bangalore, 1992

         Bangalore City, 1997

       Chingleput, TN1969

       Chingleput, TN1979

       Chingleput, TN1984

   Car Nicobar Island, 1986
                                                                                   A RT I i n I ndi a




        Trivandrum, 1991-92

            Bikaner Raj, 1992

             M       P,
              orena,M 1989

       Tiruvallur, 1999-2001

  orth
 N Zone-India 2000-02

   West Zone-India2000-02

 South Zone-India 2000-02

    East zone India 2001-03
                   INCIDENCE OF PULMONARY
                     TUBERCULOSIS IN INDIA

      Study               Period               Method            Incidence

                         1961-62                                   1.36
Bangalore Rural
                         1962-64           Repeated Surveys        0.80
Age  5years
                         1964-68                                   1.04
Def : Culture +ve

                         1968-71           Repeated Surveys,        3.83
BCG.TRIAL,
                                              passive case
Chingleput               1976-78                                    2.30
                                           finding , selective
Age > 15 years
                         1981-83              case finding          3.00

Def: Culture positive &/or Microsopy +ve

CMC – Vellore            1981-83           Active case finding      1.10
Age> 10 yrs

Def:Smear +ve
    HIV Sero-prevalence among TB Cases

                             Year of study   % HIV +ve

Govt Hospital Tanjavur, TN         1999          8.9

General Hospital, Pune, MH         2000         28.8
TB & Chest Hospital,Goa            2000         10.9
AIIMS, Delhi                     2000-02         9.4
Medical College, Lucknow         2000-01         4.3
Medical College, Aligarh         2000-01         2.8
  Multi Drug Resistance in new TB cases
                                  Year of study % MDR

23 districts of Tamilnadu         1997        3.4

DOT centres, Bangalore            1999        2.2

DTP centres, Raichur, Karnataka   1999-2000   2.5

Wardha, Maharashtra               2000-01     0.5

Jabhalpur, Madhya Pradesh         2001-02     1.0

Hoogli, West Bengal               2000-01     3.0

Mayurbhanj, Orissa                2000-02     0.7
Multi Drug Resistance in previously treated
                TB cases

                                 Year of study % MDR

TB Sanatorium, Chennai, TN        1997-2000   54.8

DOT centres, Tiruvallur, TN       1999-2000   18.3

State TB Centre, Ahmedabad, GJ     2000-01    33.0
ARI in other countries
   Country wise Epidemiology situation

 Country    Pop. in Global    %       Incidence of all
            million rank contribution      cases
                                      Total Rate
                                       (000) /100000

India       1045   1       20           1761   168
Indonesia   217    3       6            557    256
Bangladesh 144     5       4            318    221
Thailand    62     19      1            80     128
Myanmar     49     22      1            75     154
   Country wise Epidemiology situation - Continued

 Country     Incidence of ss + Prevalence    TB      HIV +     %
             Total    Rate       (ss +)   Mortality/  TB      cases
             (000) /100000      /100000    100000    cases    MDR

  India       787     75        156         37       4.6       3.4
                                                   (0.4-28)
Indonesia     250     115       272         59       0.6       0.7
Bangladesh    143     99        188        520       0.1       1.4
 Thailand     35      57        254         86        24       0.5
Myanmar       33      68         83         26        11       1.5
 Country       DOTS      Treatment DOTS detection
             population success (%)        rate
              coverage     – 2001   (ss +) - 2002 (%)
             (%) - 2002    cohort

  India         52          85             31
Indonesia       98          86             30
Bangladesh      95          84             34
 Thailand       100         56             47
 Myanmar        88          81             73
  Progress of DOTS in high burdened
               countries
                         High treatment success (>70%)
 Low treatment
                  Case detection under
    success                                     >50%
                     DOTS 10-49%
Brazil, Russia,   Afghanisthan,         Cambodia, Cango,
South Africa,     Bangladesh, China,    Myanmar, Philipines,
Uganda            Euthopia, India,      Thailand, Vietnam
                  Indonesia, Kenya,
                  Mozambique, Nigeria,
                  Pakistan, Tanzania,
                  Zimbabwe
    What is meant by control ?


• To move from high to low endemicity or
  elimination
      Objectives of TB control
           programmes
• Decrease transmission of infection by:-
      - Rapidly identifying cases
      - Adequate treatment
• Decrease deaths due to TB.
• Cure of maximum number of cases.
• To prevent relapse.
• To prevent emergence of drug resistance.
• To reduce TB in children by preventive treatment.
• IEC - Purpose ?
         Each case leads to two cases

          -_-_-



 1 Infectious case



                               20 contacts
                     2 cases
                      of TB
1 Non-infectious
How does DOTS strategy help
       control TB?
                   DOTS
• Decreases deaths
• Decreases duration of infectiousness
• Increased case detection plus high cure rate
  decreases transmission of infection that
  will ultimately lead to decline in incidence.
• Prevents emergence of MDR
  A good programme like DOTS
     reduces disease burden
• Case fatility rate reduced to <5% compared to
  60%-70% in a few years among untreated cases.
• Cure of every case under DOTS with about 4
  months diagnostic delay prevents 0.7 new smear
  positive cases.(further prevention possible by
  reducing diagnostic delay)
• Preventive treatment to each child prevents 0.03
  new case and 0.007 deaths.
How does a poor programme
  worsen the TB situation
• Poor programme with low cure rate (<50%)
  and low detection rate worsen TB situation
  by decreasing case fatility rates leading to
  increased prevalence and transmission of
  infection.
HIV prevention and control is of
 major importance towards TB
           control
 Priority to smear positive cases
• To reduce transmission of infection. A good
  DOTS       programme        would     reduce
  transmission of infections by about 73%

• Cost per DALY highest for treating smear
  positive cases.
The Cuba example
• Very low levels of MDR in Cuba

• Cuba is a low HIV country
                HIV-TB Vs. DOTS - TB trends in Tanzania

100                                                          1.2


90

                                                             1
80


70                                                                 smear positive
                                                             0.8   notification
                                                                   rate/ 100,000
60                                                                 pop
                                                                   Treatment
                                                                   completion
50                                                           0.6   rates

                                                                   ARI
40

                                                             0.4
30


20
                                                             0.2

10


 0                                                           0
      1978-82    1983-87          1988-92          1993-97
• Increased case detection will decrease transmission
  rapidly provided cure rates are high.
• It has been estimated that achievement of 70% case
  detection and 85% cure rate by 2010 will result in
  greatest benefits in cases and deaths averted in regions
  with highest burden - South East Asia, Africa and
  Western Pacific.
• Longer the time taken to reach targets, incidence will
  decrease more slowly.
• The proportion of deaths averted by DOTS would be
  greater than the proportion of cases
   – Non curative treatment can prevent death         without
     eliminating infectiousness.
   – Programme will treat non-infectious cases also
Control TB since every breadth
 counts (World TB day 2004 theme)



Business as usual will not eliminate TB

It is time for business unusual

				
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posted:3/10/2012
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