TUBERCULOSIS basic facts about TB Tuberculosis is a Chronic necrotizing disease caused by Mycobacterium tuberculosis complex. It usually affects the lungs but almost all organs can be affected. Thus it is conveniently classified into: • Pulmonary TB (PTB): accounts for 80% of all TB cases. Smear-positive PTB: 75-80% of all PTB cases Smear-negative PTB: 20-25% of all PTB cases • Extra-pulmonary TB (EPTB): accounts for 20% of all TB cases.

TB is a bacterial disease caused by Mycobacterium tuberculosis occasionally by Mycobacterium bovis These organisms are also known as tubercle bacilli (because they cause lesion called tubercles) or as acid-fast bacilli (AFB). This is because they are acid-fast (they have kept the dye even after being washed with acid and alcohol).

Tuberculous infection and tuberculosis Tuberculous infection occurs when a person carries the tubercle bacilli inside the body, but the bacteria are in small numbers and are dormant. Tuberculosis is a state in which one or more organs of the body become diseased as shown by clinical symptoms and signs.

Sources of infection The most important source of infection is the patient with TB of the lung, or pulmonary TB (PTB), and who is coughing. This person is usually sputum smear-positive. Routes by which TB is not transmitted TB is not transmitted through food and water or by sexual intercourse, blood transfusion, or mosquitoes.

Natural history of untreated TB Without treatment, by the end of 5 years 50% of PTB patients will be dead, 25% will be healthy (self-cured by a strong immune defence) and 25% will remain ill with chronic infectious TB.

Epidemiology M. tuberculosis infects a third of the world's population.

Factors that facilitate transmission of pulmonary tuberculosis are • Infectivity of the contact ( patients with heavy bacterial load) • Environment: overcrowding • Duration of contact ( prolonged exposure ) • Intimacy ( how close the source and the subject are )

The presence some disease conditions increase the likely hood of developing active TB • The commonest is co-infection with HIV, which suppresses cellular immunity. • Hematologic and other malignancies : lymphoma, leukemia, malignancies, • Chronic renal failure • Diabetes mellitus • Immune suppressive drugs like long-term corticosteroids (e.g. prednisolone) • Old age because of decreased immunity. • Malnutrition is a very important factor for the development of disease.

Clinical Manifestations Pulmonary Tuberculosis: - This can be classified as primary or post primary (Secondary). 1.Primary disease: Clinical illness directly after infection is called primary tuberculosis; this is common in children <4 years of age. Thus, it results from an initial infection. Frequently it involves the middle and lower lung zones.

Post primary disease: -If no clinical disease is developed after the primary infection, dormant bacilli may persist for years or decades before being reactivated, when this happens, it is called secondary (or post primary) tuberculosis. Therefore this is from endogenous reactivation of latent infection. It is more common in adults, and typically involves the apical lobes.

Extra-pulmonary Tuberculosis :-Commonly affected organs are lymph nodes, pleura, meninges, genitourinary tract, bones and joints, and peritoneum.

Lymph-node tuberculosis (TB lymphadenitis) :-It is seen more in HIV patients. The commonest sites are cervical and supraclavicular. Pleural tuberculosis:- Pleural involvement may be asymptomatic or patients could have fever, pleuritic chest pain and dyspnea.

Genitourinary tuberculosis: It can involve any part of the system. Dysuria, intermittent hematuria and flank pain are common presentations. But it may be asymptomatic for a long period of time. Urinalysis shows pyuria and hematuria without bacteria in majority of cases (commonly called sterile pyuria).

Skeletal Tuberculosis:- It is usually reactivation of hematogenous site or extension from a nearby lymph node. The most common sites are spine, hips and knees. • Spinal tuberculosis is called Pot's disease or tuberculosis spondylitis.

Tuberculosis Meningitis:- It is commonly seen in children and immuno-compromised people particularly patients with HIV. More than half have evidence of disease in the lungs. Patients with TB meningitis present with headache, behavioral changes and nuchal rigidity for about two weeks or more. Patients may have cranial nerve paralysis and seizure.

Pericardial Tuberculosis (TB pericarditis): It is frequently seen in patients with HIV. Patients usually present with fever, retro-sternal pain, cough, dyspnea and generalized edema because of pericardial effusion. Cardiac tamponed may appear later Constrictive pericarditis may develop as a complication of TB pericarditis even after treatment and patients can present with symptoms and signs of right sided heart failure.

Diagnosis Clinical suspicion is very important for the diagnosis of tuberculosis. Patients who have suggestive symptoms and signs for tuberculosis should undergo further tests. • AFB Microscopy :Sputum examination is extremely important in patients who have sputum production. AFB stain should be done 3 times in 2 consecutive days (spot - early morning -spot). Sputum smear is said to be positive when at least 3 AFB are seen. Smear positive TB is diagnosed when at least 2 smears are positive or one smear positive plus suggestive chest x-ray finding

Mycobacterial culture Chest x-ray ESR

Note. In keeping with good clinical and public health practice, diagnostic criteria for PTB-should include: A at least three sputum specimens negative for AFB, and A radiographic abnormalities consistent with active PTB, and No response to a course of broad-spectrum TB antibiotics, and Decision by a clinician to treat with a full course of ant tuberculosis chemotherapy.

History of previous treatment of TB In order to identify those patients at increased risk of acquired drug resistance and to prescribe appropriate treatment, a case should be defined according to whether or not the patient has previously received TB treatment.

• New: a patient who has never had treatment for TB or who has taken ant tuberculosis drugs for less than 1 month. • Relapse: a patient previously treated for TB who has been declared cured or treatment completed, and is diagnosed with bacteriologically positive (smear or culture)tuberculosis.

Treatment after failure: a patient who is started on a re-treatment regimen after having failed previous treatment. • Treatment after default. A patient who returns to treatment, positive bacteriologically, following interruption of treatment for 2 months or more.

• Transfer in. A patient who has been transferred from another TB register to continue treatment. Other. All cases that do not fit the above definitions. This group includes Chronic case, a patient who is sputum-positive at the end of a re-treatment

Case definitions Tuberculosis suspect. Any person who presents with symptoms or signs suggestive of TB, in particular cough of long duration (more than 2 weeks) • Case of tuberculosis. A patient in whom TB has been bacteriologically confirmed or diagnosed by a clinician.

• Definite case of tuberculosis: a patient with positive culture for the M.tuberculosis complex.

TB treatment category Patients Recommended Treatment /Regimen Category 1 • New smear positive PTB • Smear –ve PTB with extensive TB • Sever forms of extra pulmonary TB DOTs short course HRZE/S for 2 months + HR 4 MO or HE 6 MO Or H3R3 for 4 MO Category 2 • Relapse • Treatment Failure • Return after Default Retreatment 2HRZES/ 1HRZE 5ERH Category 3 • Smear negative PTB with limited • EPTB less ever form • Children between 7 and 14 years old with any type of TB, who are not seriously ill 2HRZ or 2H3R3E3 Category 4 • Chromic cases 2nd line an TB drug.

Anti Tuberculosis Chemotherapy Aim of Treatment of Tuberculosis • To cure the patient from the diseases and prevent death and complications • To decrease transmission of Tuberculosis Treatment of tuberculosis has two phases, • The intensive (initial) phase: combination of 3 or more drugs is given for 2months. In the retreatment regimen it continued for 3 months. This is to decrease the bacterial load and make the patient non-infectious rapidly.

• Continuation phase: Two or three drugs used for 4 -5 months • Continuation phase: Two or three drugs used for 4 -5 months. This phase follows the intensive phase and the aim is to achieve complete cure.

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