TB is an airborne disease caused by the bacterium Mycobacterium tuberculosis (M.
tuberculosis). M. tuberculosis and seven very closely related mycobacterial species (M. bovis,
M. africanum, M. microti, M. caprae, M. pinnipedii, M. canetti and M. mungi) together
comprise what is known as the M. tuberculosis complex. Most, but not all, of these species
have been found to cause disease in humans. In the United States, the majority of TB cases
are caused by M. tuberculosis. M. tuberculosis organisms are also called tubercle bacilli.
Each year, we commemorate World Tuberculosis (TB) Day on March 24 to raise public
awareness about the devastating health, social and economic consequences of TB, and to
step up efforts to end the global TB epidemic. The date marks the day in 1882 when Dr
Robert Koch announced that he had discovered the bacterium that causes TB, which
opened the way towards diagnosing and curing this disease.
India is the highest TB burden country in the world having an estimated incidence of 26.9 lakh
cases in 2019 (WHO). To address this, the ability to achieve complete surveillance coverage is the
The theme of World TB Day 2020 - ‘It’s time’ – puts the accent on the urgency to act on the
commitments made by global leaders to:
scale up access to prevention and treatment;
ensure sufficient and sustainable financing including for research;
promote an end to stigma and discrimination, and
promote an equitable, rights-based and people-centered TB response.
4. Transmission of TB
M. tuberculosis is carried in airborne particles, called droplet nuclei, of 1– 5
microns in diameter. Infectious droplet nuclei are generated when persons who
have pulmonary or laryngeal TB disease cough, sneeze, shout, or sing.
Depending on the environment, these tiny particles can remain suspended in the
air for several hours. M. tuberculosis is transmitted through the air, not by surface
contact. Transmission occurs when a person inhales droplet nuclei containing M.
tuberculosis, and the droplet nuclei traverse the mouth or nasal passages, upper
respiratory tract, and bronchi to reach the alveoli of the lungs
5. Factors that Determine the Probability of
Transmission of M. tuberculosis
Susceptibility Susceptibility (immune status) of the exposed
Infectiousness Infectiousness of the person with TB disease
is directly related to the number of tubercle
bacilli that he or she expels into the air.
Persons who expel many tubercle bacilli are
more infectious than patients who expel few
or no bacilli
Environment Environmental factors that affect the
concentration of M. tuberculosis organisms
Exposure Proximity, frequency, and duration of
Microscopy of specially stained sputum is the main test for diagnosing TB (1‐2 days)
TB bacilli seen in the sputum sample using a microscope (smear positive or AFB +)
Detects only ½of all TB and 1/3rd of HIV related TB
PLHIV higher proportion of –sputum negative pulmonary TB –extrapulmonary TB
X ‐ray also has a role for diagnosing TB if smear negative.
Role of culture: (takes 3 ‐4 wks.)
EPTB may require tissue samples/culture
Diagnostic process will differ depending on the setting (rural/urban/laboratory capacity/ava
ilability of X-ray/culture)
7. How is TB diagnosed?
–Sputum smear microscopy
–TST or Mantoux or PPD
8. Tuberculosis Case definition
TB case -A patient in whom tuberculosis has been confirmed by bacteriology
ordiagnosed by a clinician.
Smear positive pulmonary TB case -A patient with one or more positive sputum
smear examinations (direct smear microscopy) AFB+.
Smear negative pulmonary TB case –A patient with two sputum smear
examinations negative for AFB; X ray suggests TB, unresponsive to a course of broad-
spectrum antibiotics (except in a patient with strong clinical evidence of HIV infection); and
a decision by a clinician to treat with anti tuberculosis chemotherapy; or positive culture but
negative AFB sputum examinations.
Extrapulmonary TB case -one culture-positive specimen, or histological or strong
clinical evidence. Followed by decision by a clinician to treat with a full course of anti-
TB is treatable and curable, even in people living with HIV.
First line TB drugs:-
Rifampicin(R), Isoniazid(H) ,Ethambutol(E) , Pyrazinamide(Z)
Gaps in first-line treatment:-
High pill burden
Long duration of treatment
Drug stock outs
Interactions with ARVs
Little to no pediatric data
10. Performance and Achievement in
2019 (Drug Sensitive TB)
For the first time in the history of TB program implementation, total TB case
notification during 2019 has crossed 24 lakhs which include 6.79 lakh cases notified
from the private sector and 17.3 lakh notified from the public sectors. Among the
above, 16.8 (94%) and 5.9 (95%) patients were initiated on treatment in public and
private sector respectively.
used 58,330 4 FDC and 91,159 3 FDC blisters of free drugs for private sector TB
patients treatment. The ‘free provision of diagnostic and drugs’ is expected to
reduce the out of pocket expenditure among TB patient and their families.
11. So how do we prevent TB infection and disease?
Primary prevention aims to block infection.
Secondary prevention aims to block progression of an infection to active disease.
*How could you prevent TB infection?
1.Involve patients & community in advocacy campaigns
2.Infection control plan
3.Safe sputum collection
4.Cough etiquette and cough hygiene
5.Triage TB suspects to fast tract or separation
6.Rapid TB diagnosis and treatment
7.Improve room air ventilation
8.Protect health care workers
10.Monitor infection control practices.
12. How can we prevent TB disease?
Bacillus Calmette-Guerin (or BCG) vaccine - The Bacille Calmette- Guérin
(BCG) is the ONLY successful TB vaccine Was introduced in 1921. BCG is the world’s
most widely administered vaccine.
Isoniazid preventive therapy (IPT) – Isoniazid treatment for 6 months given to
people with HIV can reduce by 40-60% .
Antiretroviral therapy (ART) for people with HIV - ART helps to restore
immune function. ART can greatly reduce the risk of TB in a person living with HIV. But
risk still elevated to about 2x that in a person without HIV
To meet the ambitious goal pronounced by our Honorable Prime Minister at the Delhi End TB
Summit in March 2018 of ending the TB epidemic by 2025 from the country, five years ahead
of SDG goals for 2030, responding to which, some States/ UTs have committed to end TB even
before 2025 - Kerala (2020), Himachal Pradesh (2021), Sikkim, Lakshadweep (2022)
Chhattisgarh, Jammu & Kashmir, Madhya Pradesh, Tamil Nadu and Bihar, Jharkhand,
Puducherry and Dadra Nagar Havelli & Daman Diu (2025). The programme has now been
renamed as National Tuberculosis Elimination Programme, to invigorate the fight in alignment
with this ambition.
The TB Sample Transport Network has been widened through support from Department of
Post’s services for specimen transportation from peripheral health facilities to TB diagnostic
laboratories. This will help expand drug susceptibility testing services. The last three years has
seen several policies and interventions augmenting the ambitious target of ending TB in India.
The coming years will see the programme build on the progress already made and intensify
efforts at expanding access and improving the quality of services to ensure optimum impact.
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