Dr. Essam El Moghazy

NTP Egypt

The Global burden of TB in

20101.3 million

deaths in 2008 –98% of these

in developing world

11–13% of incident cases

were HIV-positive380,000 deaths

due to TB/HIV

250 000 cases

MDR-TB

9.4 million new cases in 2009 – 80% in 22 high-

burden countries

The burden of TB in Egypt

2010

WHAT IS TUBERCULOSIS?

• Tuberculosis is an infectious disease caused mainly by Mycobacterium tuberculosis.

• Tuberculosis can affect most organs in the body, but the lung is the main organ affected.

• If left untreated, each person with smear-positive pulmonary TB will infect, on average, between 10 and 15 persons in each year.

• Those who will be infected with TB will not necessarily get the disease. The immune system “walls off” the TB bacilli, which can lie dormant for years.

• When someone’s immune system is weakened, chances of developing TB are increased. On average, 10 percent of the infected individuals develop the disease during their lifetime.

SOURCE OF INFECTION

• There are a number of Mycobacteria responsible for causing the disease in human beings: – Mycobacterium tuberculosis;

– M. Africanum; and

– M. Bovis.

TRANSMISSION OF INFECTION

• Inhalation: Inhalation of droplet nuclei, from a patient with smear positive pulmonary Tuberculosis, caused by sneezing or coughing is the most common way of transmission of TB infection.

• Ingestion: Infection usually occurs through milk contaminated with M. Bovis

• Coetaneous: Very rare and of no epidemiological importance (e.g. ear piercing; tattoos)

• Congenital: Very rare – the fetus acquires the infection from the diseased mother.

When to suspect TB?

• Tuberculosis should be considered if the patient has:– Persistent cough for two weeks or more; every individual

presenting this symptom at the health facility should be considered a TB suspect

– Production of sputum which may be blood-stained

– Breathlessness and chest pain

– General symptoms such as: loss of appetite; loss of weight; night sweats and fever

– A history of contact with a TB patient

• The symptoms and signs of extra-pulmonary TB depend on the organ involved, e.g.: Chest pain in TB pleurisy and sharp angular deformity of the spine in Pott’s disease

The diagnosis of adolescents and adults

with symptoms suggestive of pulmonary

TB should be confirmed by detecting

Acid Fast Bacilli (AFB) through the

direct smear examination of the sputum.

A) Bacteriology

1. Detection of TB bacilli

Direct smear microscopy• The direct smear microscopy of sputum is a reliable

and simple technique for detecting Mycobacteria in order to diagnose pulmonary TB.

• The method consists of microscopic examination of a specimen of sputum that has been spread on a slide, and stained by the Ziehl-Neelsen method.

Culture

• Culture of sputum is more sensitive than smear examination, but it takes 4 to 8 weeks before the result is known.

• It also requires well-equipped laboratories with skilled staff.

• Culture allows the study of anti-TB drug resistance.

2 .Detection of the immune response to TB bacilli: Tuberculin

skin Test (TST)• When a healthy person is infected for the first time with the

tubercle bacilli, the body will develop a specific immune response. This immune reaction (cell-mediated immunity) can be assessed by TST.

• Tuberculin is an antigen produced from dead tubercle bacilli, purified protein derivative PPD of. In the Mantoux test, 0.1 ml of tuberculin is injected intradermally.

• Most people infected by M. tuberculosis or vaccinated by BCG will react to TST and develop an induration at the site of injection.

• The diameter of this induration is measured after 48 to 72 hours.

3. Histo-pathological diagnosis of TB

• Through a biopsy of the suspected lesion e.g. lymph node biopsy and pleural biopsy.

4. Detection of metabolic end products of TB bacilli: BACTEC

• BACTEC is complicated and expensive, and is available only in specialized centers.

5. Detection of DNA of TB bacilli: polymerase chain reaction (PCR)

• PCR is 100% specific, but it its sensitivity is about 85 %. Moreover, it is expensive and requires specialized skills and equipment.

B) Radiography• X-rays are not specific. TB can mimic any chest

disease on the X-ray. Furthermore, it is difficult to differentiate in an X-ray between clinically active and inactive old lesions of pulmonary TB.

• It is not justified to start anti-TB treatment on radiographic basis.

• However, radiography can be of help in certain occasions, such as childhood TB; miliary TB; hilar lymphadenopathy; extra-pulmonary TB and, lack of sputum.

What determines case definition?

• The Three determinants of case definition are:– Site of TB disease.

– Bacteriology (result of sputum smear).

– History of previous treatment of TB.

Note. Any person given treatment for tuberculosis should be recorded as a case. Incomplete "trial" tuberculosis treatment should not be given as a method for diagnosis.

• New caseA patient who has never had treatment for TB or who has taken drugs for less than one month

• Previously treated

patients have received 1 month or more of anti-TB

drugs in the past, may have positive or negative

bacteriology and may have disease at any

anatomical site.

They are further classified by the outcome of their

most recent course of treatment

• Relapse A patient who is declared cured by a physician, after one full course of chemotherapy, and has become bacteriologically positive (indicates positive smear, culture or other newer means of identifying M. tuberculosis)

• Treatment failureA patient who, while on treatment, remained or became again

smear-positive 5 months or later after commencing treatment;

or,

A patient who was initially smear-negative before starting treatment and became smear-positive after the second month of treatment

Treatment after interruption• A patient who interrupts his treatment for 2 months or

more (defaulter) and returns with smear positive

sputum

Others• A patient who was either smear-negative pulmonary TB

or extra-pulmonary TB, completed treatment and returned with symptoms and active disease or chronic cases.

Chronic case:• A patient who remained or became again smear-

positive after completing a fully supervised

retreatment regimen.

Treatment category

Patient CategoryInitialContinuation

INew smear +ve PTB.New smear –veNew forms of extra-Pulmonary TB.

2/EHRZ

OR

2/SHRZ

4/HR

Treatment category

Patient CategoryInitialContinuation

IISputum smear +veRelapse.Treatment failure.Treatment after interruption.

2/SHRZE

then

1/HRZE

5/HRE

PulmonaryPulmonaryExtra PulmonaryExtra Pulmonary

Positive Positive Negative Negative

TAITAI TAFTAF RelapseRelapse NewNew

2HRZES/1HRZE/5HRE2HRZES/1HRZE/5HRE 2HRZE(S)/4HR2HRZE(S)/4HR

Re treatment cases

TUBERCULOSIS

Drugs and DosesESSENTIAL DRUG RECOMMENDED DAILY DOSAGE

(DOSE RANGE),mg/kg

Isoniazid (H)5 (4–6)

Rifampicin (R)10 (8–12)

Pyrazinamide (Z)25 (20–30)

streptomycin (S)15 (12–18)

Ethambutol (E)15 (15–20)