Tuberculosis from Park (PSM) summary with focus on end TB, diagnosis algorithm, treatment, prevention, nikshay mitra and presumptive TB case

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Tuberculosis - Park's Textbook of Preventive and Social Medicine (PSM)

Comprehensive Summary

1. DEFINITION & PROBLEM STATEMENT

Tuberculosis is a specific infectious disease caused by Mycobacterium tuberculosis, primarily affecting the lungs (pulmonary TB), but also the intestine, meninges, bones and joints, lymph glands, and skin. "Bovine tuberculosis" from cattle can also be transmitted to humans.

Global Burden:

Globally ~10 million people had TB in 2019
1.2 million TB deaths among HIV-negative + 208,000 among HIV-positive people
Men (≥15 yrs) = 56%, women = 32%, children = 12%
8.2% of all cases were people living with HIV (PLHIV)
An undiagnosed/untreated person can infect 10-15 people per year
About 1/3 of the global population is asymptomatically infected; 5-10% will develop clinical disease in their lifetime

India's Burden:

India accounts for the largest share of global TB burden (26% of new TB cases as per 2019 data)
NTEP (National Tuberculosis Elimination Programme) replaced RNTCP in 2020
India aims to eliminate TB by 2025 (5 years ahead of the global SDG target of 2030)

2. PRESUMPTIVE TB CASE (WHO 2013 Revised Definition)

Presumptive TB refers to a patient who presents with symptoms or signs suggestive of TB. This was previously known as a "TB suspect."

A person is considered presumptive TB if they have:

Cough for 2 weeks or more (the cardinal symptom)
Fever, night sweats, weight loss, haemoptysis
Any combination of symptoms suggestive of pulmonary or extrapulmonary TB

Early identification of people with a high probability of having active TB (presumptive TB) is described in Park as "the most important activity of the case-finding strategy."

3. CASE DEFINITIONS (WHO 2013 Revised)

Category	Definition
Bacteriologically confirmed TB	Positive by smear microscopy, culture, or WHO-endorsed rapid diagnostic test (WRD such as Xpert MTB/RIF) - must be notified regardless of treatment status
Clinically diagnosed TB	Does not meet bacteriological confirmation criteria but diagnosed by clinician who decides on full TB treatment course; includes X-ray abnormalities, suggestive histology, EPTB without lab confirmation

Classification also based on:

Anatomical site (Pulmonary / Extrapulmonary)
History of previous treatment
Drug resistance
HIV status

By treatment history:

New patients - never treated for TB or taken anti-TB drugs for < 1 month
Previously treated - received 1 month or more of anti-TB drugs previously

PTB - involves lung parenchyma or tracheobronchial tree (miliary TB = PTB). A patient with both PTB and EPTB = classified as PTB.

EPTB - pleura, lymph nodes, abdomen, genitourinary tract, skin, joints and bones, meninges.

4. DIAGNOSIS ALGORITHM (NTEP 2019)

Case-Finding Tools

Microbiological Confirmation:

Sputum Smear Microscopy (AFB)
- Ziehl-Neelsen (ZN) staining
- Light-emitting diode fluorescence microscopy (LED FM) - superior sensitivity to conventional ZN
Culture - Solid (Lowenstein-Jensen) or automated liquid systems (BACTEC MGIT 960) - takes 2-8 weeks; used for DR-TB follow-up
Drug Sensitivity Testing (DST) - Proportionate sensitivity testing
Rapid Molecular Tests:
- CB-NAAT / Xpert MTB/RIF (TrueNAT) - detects MTB DNA and rifampicin resistance via PCR; results in 90 minutes
- Line Probe Assay (LPA) - First-line LPA (FL-LPA) for RIF & INH resistance; Second-line LPA (SL-LPA) for fluoroquinolone & second-line injectable resistance

Supportive Tools:

Chest X-ray
Tuberculin Skin Test (TST/Mantoux) - induration ≥10 mm (≥5 mm in HIV/immunocompromised)
Interferon Gamma Release Assay (IGRA) - QuantiFERON-TB Gold, T-SPOT TB test - not affected by BCG vaccination
Histopathology

Diagnosis & Initiation Algorithm (Drug-Sensitive TB)

Presumptive TB patient
        ↓
Sputum Smear (ZN / LED FM) — 2 specimens (Spot + Early morning)
        ↓
First smear POSITIVE
→ Not at risk of DR-TB: Microscopically confirmed TB
→ At risk of DR-TB: Send for CB-NAAT
        ↓
First smear NEGATIVE
→ CXR: if suggestive of TB
→ 2nd sample: Smear + CB-NAAT simultaneously
        ↓
CB-NAAT Results:
  - MTB detected, RIF sensitive → DS-TB treatment
  - MTB detected, RIF resistant → DR-TB workup / treatment
  - MTB not detected, negative smear → Clinically diagnosed TB if CXR positive

Sputum Smear Notes:

Minimum 10,000 organisms/mL needed for smear positivity
One positive specimen out of two is sufficient to declare smear-positive TB
Max 20 slides per technician per day to avoid visual fatigue
Serological tests are banned in India (poor specificity, antibody-based)

5. TREATMENT

Drug-Sensitive TB (DS-TB) - Standard Regimen (NTEP Daily Regimen, 2016 onwards)

NTEP switched from thrice-weekly intermittent to daily fixed-dose combination (FDC) regimen:

Phase	Regimen	Duration	Drugs
Intensive Phase (IP)	2HRZE	8 weeks (56 doses)	Isoniazid (H) + Rifampicin (R) + Pyrazinamide (Z) + Ethambutol (E)
Continuation Phase (CP)	4HRE	16 weeks (112 doses)	H + R + E (pyrazinamide stopped)

FDCs used:

Adults IP: 4-FDC (HRZE)
Adults CP: 3-FDC (HRE)
Paediatric IP: Dispersible 3-FDC (HRZ)
Paediatric CP: Dispersible 2-FDC (HR)

Extension of CP: 12-24 weeks in CNS TB, skeletal TB, disseminated TB - based on specialist recommendation.

Drug Dosages (Adults / Children):

Drug	Adults	Children	Max in children
Isoniazid	10 mg/kg/day	5 mg/kg/day	300 mg
Rifampicin	15 mg/kg/day	10 mg/kg/day	600 mg
Pyrazinamide	35 mg/kg/day	35 mg/kg/day	-
Ethambutol	15 mg/kg/day	15 mg/kg/day	-

Steroids as adjunctive therapy are useful in TB pericarditis and meningeal TB (initial high dose tapered over 6-8 weeks).

Anti-TB Drugs: Key Points

First-Line Bactericidal:

Rifampicin (R) - most potent sterilizing agent; active against "persisters"/dormant bacilli in caseous lesions; turns urine red (compliance marker); hepatotoxic; never used alone
Isoniazid (H) - most powerful anti-TB drug overall; active against intracellular and extracellular bacilli; active against rapidly multiplying bacilli; distributed in CSF; inexpensive and well-tolerated
Pyrazinamide (Z) - bactericidal; especially active in acidic environment inside macrophages; key to reducing duration of treatment
Streptomycin (S) - first anti-TB drug; parenteral; nephrotoxic and ototoxic; not for pregnant women; resistance develops rapidly if used alone

First-Line Bacteriostatic:

Ethambutol (E) - prevents emergence of resistance; major side effect is retrobulbar neuritis (not at usual dose); replaced PAS almost entirely

Second-Line Drugs:

Fluoroquinolones (Levofloxacin, Moxifloxacin)
Ethionamide / Prothionamide
Capreomycin, Kanamycin, Amikacin (injectable; similar to Streptomycin)
Cycloserine (mainly bacteriostatic)
Thioacetazone - NEVER in HIV patients (fatal skin reactions)
Bedaquiline (BDQ) - new class (diarylquinoline); targets mycobacterial ATP synthase; extended half-life (~5.5 months post-stopping); improves culture conversion in MDR-TB
Delamanid (Dlm)
Linezolid (Lzd)
Clofazimine (Cfz)
Cycloserine (Cs)

Drug-Resistant TB (DR-TB) Treatment (NTEP / WHO 2019 Guidelines)

Three regimens:

All-oral H mono/poly DR-TB regimen: (6) Lfx R E Z
Shorter MDR-TB regimen: (4-6) Mfx Km/Am Eto Cfz Z Hh E → 5 Mfx Cfz Z E
All-oral longer MDR-TB regimen: (18-20) Bdq (6) Lfx Lzd Cfz Cs

Grouping for longer MDR-TB regimen (WHO):

Group	Medicines
Group A (include all 3)	Levofloxacin/Moxifloxacin (Lfx/Mfx), Bedaquiline (Bdq), Linezolid (Lzd)
Group B (add 1-2)	Clofazimine (Cfz), Cycloserine (Cs)
Group C (add to complete regimen)	Ethambutol, Delamanid, Pyrazinamide, Imipenem-cilastatin, Meropenem, Amikacin/Streptomycin, Ethionamide/Prothionamide, PAS

Fully oral regimens have priority per 2019 consolidated guidelines; injectables no longer among priority medicines for longer MDR-TB regimens.

DOTS (Directly Observed Treatment Short-Course)

During intensive phase: health worker watches patient swallow every dose
During continuation phase: patient issued medicine for 1 week in a multiblister combipack; first dose taken in presence of health worker; empty combipack returned as compliance check
Drugs provided in patient-wise boxes

Latent TB Treatment (Recommended Populations)

Strongly recommended:

PLHIV
Children under 5 who are household contacts of pulmonary TB cases

Other indications: recent TB contacts, silicosis, diabetes, chronic renal failure, homeless, prisoners, immigrants from high-burden countries.

Recommended regimens:

Isoniazid daily or twice-weekly for 9 months
Isoniazid + Rifapentine once weekly for 12 weeks
Rifampicin (or rifabutin) daily for 4 months

6. TREATMENT OUTCOMES (WHO Definitions)

Outcome	Definition
Cured	Bacteriologically confirmed; smear/culture negative in last month of treatment AND at least one previous occasion
Treatment completed	Completed without failure but no bacteriological documentation of negative results
Treatment failed	Sputum smear/culture positive at month 5 or later during treatment
Died	Died for any reason before or during treatment
Lost to follow-up	Did not start or treatment interrupted for ≥2 consecutive months
Not evaluated	No outcome assigned (including transferred-out cases)
Treatment success	Sum of Cured + Treatment Completed

7. PREVENTION & CONTROL

Two Fundamental Components:

Case-finding and treatment (most powerful weapon - curative)
BCG vaccination (preventive)

Case-Finding Strategies:

a. Passive Case Finding - patients who present on their own with symptoms (>60% of PTB patients seek care on their own initiative)

b. Intensified TB Case Finding (ICF) - provider-initiated, targets:

Community screening (mobile/fixed facilities, door-to-door)
Institutional screening (healthcare facilities, congregate settings like prisons, shelters, refugee camps)

Vulnerable Groups (Key Populations for TB):

Category	Examples
Increased exposure	Prisoners, sex workers, miners, healthcare workers, urban slum dwellers, TB contacts
Limited access to services	Migrant workers, homeless, tribal/indigenous populations, refugees, those with disabilities
Biological/behavioral risk	PLHIV, diabetes, silicosis, immunosuppressive therapy, malnourished, tobacco users, alcohol use disorders, IDUs

BCG Vaccination:

Protects against severe forms of TB in children (miliary TB, TB meningitis)
Part of the Universal Immunization Programme in India
Does not reliably prevent pulmonary TB in adults

8. THE END TB STRATEGY (WHO - adopted 2015)

TB is the deadliest infectious disease measured by annual deaths. It claims 3 lives every minute. Of 9 million annual cases, more than 3 million are missed - not diagnosed, treated, or registered.

Evolution of Global TB Strategies:

Strategy	Period	Focus
DOTS Strategy	1994-2005	Government commitment, passive case detection, standardized short-course chemotherapy, drug supply, monitoring
Stop TB Strategy	2006-2015	HIV-associated TB, MDR-TB, engaging private sector, civil society
End TB Strategy	2016-2030	Holistic health + social interventions to end the epidemic

Between 2000-2014, improvements in TB diagnosis and treatment saved 43 million lives and helped meet the MDG target of halting and reversing the TB epidemic. However, incidence declined very slowly, as TB is linked to poverty beyond just a biomedical problem.

End TB Strategy: 3 Pillars, 10 Components

Pillar 1: Integrated, patient-centred care and prevention

Early diagnosis of TB including universal DST; systematic screening of contacts and high-risk groups
Treatment of all people with TB including drug-resistant TB; patient support
Collaborative TB/HIV activities; management of comorbidities
Preventive treatment of persons at high risk; vaccination against TB

Pillar 2: Bold policies and supportive systems 5. Political commitment with adequate resources for TB care and prevention 6. Engagement of communities, civil society organizations, and public and private care providers 7. Universal health coverage policy, and regulatory frameworks for case notification, vital registration, quality and rational use of medicines, and infection control 8. Social protection, poverty alleviation, and actions on other determinants of TB

Pillar 3: Intensified research and innovation 9. Discovery, development, and rapid uptake of new tools, interventions, and strategies 10. Research to optimize implementation and impact, and promote innovations

Four Underlying Principles:

Government stewardship and accountability
Coalition with civil society organizations and communities
Protection and promotion of human rights, ethics, and equity
Adaptation of the strategy and targets at country level with global collaboration

End TB Milestones (from 2015 baseline):

Year	Reduction in TB Deaths	Reduction in TB Incidence
2020	35%	20%
2025	75%	50%
2030	90%	80%

Ultimate goal (2035): 95% reduction in TB deaths; 90% reduction in TB incidence; zero TB-affected families facing catastrophic costs.

9. NIKSHAY & NIKSHAY MITRA

NIKSHAY (Launched May 2012)

Nikshay = NI + KSHAY (Hindi) = "Eradication of TB"

A case-based web-based IT system developed by Central TB Division in collaboration with the National Informatics Centre (NIC) for TB surveillance.

Functional components:

Master management and user details
TB patient registration with details of: diagnosis, DOT provider, HIV status, follow-up, contact tracing, outcomes
Solid/liquid culture, DST, LPA, CB-NAAT details
DR-TB patient registration
Referral and transfer of patients
Private health facility registration and TB notification
Mobile application for TB notification
SMS alerts to patients on registration
SMS alerts to programme officers
Automated periodic reports: Case finding, Sputum conversion, Treatment outcome

Additional features:

IT-enabled adherence tools like 99DOTS (pill-in-envelope adherence monitoring)
Direct benefit transfer by linking TB patients in Nikshay with AADHAR and PEMS for benefits delivery

NIKSHAY MITRA (Launched 9 September 2022)

Formally launched under Pradhan Mantri TB Mukt Bharat Abhiyan (PMTBMBA) by the President of India, Smt. Draupadi Murmu, to strengthen community participation in TB care.

Key features:

Encourages individuals, NGOs, corporates, faith-based organizations, cooperative societies, and political parties to adopt TB patients
Functions through the Nikshay 2.0 portal
A Nikshay Mitra can adopt a minimum of 1 consenting TB patient (DS-TB or DR-TB) undergoing treatment for a minimum of 1 year and a maximum of 3 years (updated 2025-26 guidance: minimum 6 months)
Mitras sponsor locally available, culturally accepted food kits valued at approximately INR 800/month per patient until treatment completion

Types of support provided:

Nutritional support (food baskets - rice/wheat, pulses, oil, groundnut)
Social/psychological support
Vocational/economic support

Who can become a Nikshay Mitra?

Individuals (CSR, charitable)
Non-governmental organizations (NGOs)
Corporates (through CSR)
Faith-based organizations
Cooperative societies
Political parties

Scale as of January 2026:

More than 7 lakh Nikshay Mitras registered
Over 22 lakh TB patients received nutritional support
More than 49 lakh nutritional food baskets distributed nationwide

Purpose: Complements Nikshay Poshan Yojana (Government provides INR 500/month to TB patients); Nikshay Mitra addresses the social, psychological, and financial burden that government schemes do not fully cover.

10. TB NOTIFICATION (Mandatory - Government Order, 7 May 2012)

It is mandatory for all healthcare providers (public and private) to notify every TB case to local authorities (District Health Officer/Chief Medical Officer/Municipal Health Officer) every month in a prescribed format.

Ban on TB Serology: Import, manufacture, sale, distribution, and use of TB serological tests is banned by the Government of India due to poor specificity.

11. DRUG RESISTANCE - KEY DEFINITIONS

Type	Definition
Primary (Pre-treatment) resistance	Resistance in a patient who has NOT previously received the drug in question
Secondary (Acquired) resistance	Resistance developing in a patient who WAS previously treated
MDR-TB	Resistant to at least Rifampicin AND Isoniazid (the two most powerful first-line drugs)
RR-TB	Rifampicin-resistant TB (detected by any method)
XDR-TB	MDR-TB + resistant to any fluoroquinolone + at least one second-line injectable
Pre-XDR-TB (WHO 2021)	MDR/RR-TB + resistance to any fluoroquinolone

Quick Reference: Mnemonics & High-Yield Points for Exams

Point	Key Fact
Presumptive TB	Symptoms/signs suggestive of TB (≥2 weeks cough - key symptom)
Smear positivity threshold	≥10,000 organisms/mL
One positive smear	Sufficient to diagnose smear-positive TB
Treatment regimen (DS-TB)	2HRZE / 4HRE (daily)
End TB target (India)	TB elimination by 2025
End TB global target	2030 (SDG 3)
Nikshay launched	May 2012
Nikshay Mitra launched	9 September 2022
Nikshay Mitra - minimum adoption	1 consenting TB patient for min. 6 months to 1 year
Thioacetazone contraindication	NEVER in HIV patients (fatal skin reaction)
Steroid use in TB	Meningeal TB and TB pericarditis
CP extension	CNS TB, skeletal TB, disseminated TB (up to 24 weeks beyond standard)
TB Notification made mandatory	7 May 2012 (Govt. of India)
Ban on serology	Banned by Govt. of India
DOTS principle	All drugs observed (IP) + combipack with first dose observed (CP)

Source: Park's Textbook of Preventive and Social Medicine (PSM), 26th Ed. - Chapter on Tuberculosis, pp. 206-240. Nikshay Mitra data also supplemented from PMC article on Nikshay Mitra and Guidance Document 2026.

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