Tb

INFECTIOUS DISEASES

Tuberculosis

Dr. Farooq AhamdAssistant Professor

Community MedicineRawalpindi Medical College

Rawalpindi

WHO Slogan for 2009

24 March commemorates the day in 1882 when Dr Robert Koch astounded the scientific community by announcing that he had

discovered the cause of tuberculosis, the TB bacillus

Mycobacterium Tuberculosis

Epidemiology World

Epidemiology Pakistan

• Estimated incidence of TB is around 250,000 per year in Pakistan & existing patient population of around 1.8 million.

• TB kills 64,000 people in Pakistan each year, accounting for 26% of the nation's avoidable deaths

• Most patients are ages 15 to 45; 52% are males; and 48% are females, according to government figures

• Pakistan ranks 6th among the 22 high burden countries of TB in the world

• It has declared TB as national emergency in 2001

The Stop TB Strategy at a glance, 2009

VISION A world free of TB

GOAL To dramatically reduce the global burden of TB by 2015 in line with the Millennium Development Goals and the Stop TB Partnership targets

OBJECTIVES 1. Achieve universal access to quality diagnosis and patient-centred treatment2. Reduce the human suffering and socioeconomic burden associated with TB3. Protect vulnerable populations from TB, TB/HIV and drug-resistant TB4. Support development of new tools and enable their timely and effective use

TARGETS 1. MDG 6, Target 8: Halt and begin to reverse the incidence of TB by 20152. Targets linked to the MDGs and endorsed by Stop TB Partnership:

a. 2005: detect at least 70% of infectious TB cases and cure at least 85% of themb. 2015: reduce prevalence of and deaths due to TB by 50%c. 2050: eliminate TB as a public health problem

Important Definitions

• Prevalence of Infection• Annual infection rate (incidence of infection)• Case Rate ( Prevalence of disease)• Incidence of new case• Prevalence of suspect cases• Prevalence of drug resistant case• Mortality rate

Important Definitions

1. Sputum Smear2. Smear Positive TB3. Smear Negative TB4. Adherence/Compliance

5. New Case6. Relapse

7. Failure Case8. Return after default9. Transfer in10.Transfer out11.Cured12. Treatment Completed

Agent, Host & Environment

Tuberculin testThe tuberculin skin test (TST) is not a test for immunity to TB, but rather a measure of the degree of tuberculin hypersensitivity as measured by a cell-mediated immune response. The Mantoux test, the Heaf test and the tuberculin tine test—all variants of the tuberculin skin test—can deliver tuberculin PPD into the skin.

Tuberculin test False Negative Tuberculin Skin

Test • Out-of-date tuberculin is used. • Tuberculin leaks at the injection site. • Testing is undertaken too early in cases of primary

exposure, before hypersensitivity has developed. (A hypersensitivity reaction generally takes six to eight weeks to develop.)

• The injection is too deep. • The test reading is undertaken too early (before 48 hours)

or too late (after one week). • The person has an inter current viral infection (such as

measles) or has had a recent live viral immunisation. • The person is undergoing corticosteroid therapy

(especially if long term) or immunosuppressive therapy.

• The person is suffering from malnutrition, perhaps from a period in a refugee or prison camp, or from significant cachexia.

• The person is elderly. • The person has a medical condition that may result in

partial immunosuppression, such as diabetes, sarcoidosis, advanced alcoholism, renal failure, massive trauma or burns.

• The person is an injecting drug user. • The person has any malignancies, especially lymphoma. • The person has HIV/ AIDS. • The person is seriously ill, including when they have

advanced or miliary TB.

Tuberculin test False Negative Tuberculin Skin

Test

A false positive TST can occur as a result of: • Recent BCG vaccination • A ruptured small venule at the time of

injection • Faulty test interpretation, such as the

measurement of erythema rather than of induration.

Tuberculin testFalse Positive Tuberculin Skin

Test

QuantiFERON-TB Assay

a new blood test that is able to measure quantitatively the production of the cytokine Interferon-γ by lymphocytes sensitised to mycobacterial proteins using an ELISA technique.

TB ControlCase finding

ATT

Patients who interrupt Treatment

DOTS

• Directly observed administration of drugs• Short course (six month) treatment• A reliable, affordable supply of drugs• Case detection (laboratory confirmation, particularly smear-positive pulmonary TB)• Reliable surveillance, including recording and

treatment include: • Government commitment to TB control.

DOTS has 5 elements:

1. Political commitment with increased and sustained financing

2. Case detection through quality-assured bacteriology

3. Standardized treatment with supervision and patient support

4. An effective drug supply and management system

5. Monitoring and evaluation system, and impact measurement

DOTS

WHO Fact sheet 2008

DOTS

• 184 countries have adopted DOTS, although services in

• many countries need to be expanded and strengthened

• Funding for TB control implementation has increased,• but for 2008 there is still a shortfall of US$ 1billion for

the 90 countries with 91% of global TB cases• Nearly 32 million TB patients have been treated under

DOTS since 1995

WHO Fact sheet 2008

Chemoprophylaxis

BCG

NTP