According to the World Health Organization (WHO) , the estimated incidence rate of tuberculosis in the Philippines is 320 per 100,000 people. The country ranks ninth among the 22 countries worldwide with high burden tuberculosis incidence, that account for 80% of the world’s TB case burden. In the Western Pacific region, we rank second in case notification and third in case density. Tuberculosis is the 6th leading cause of morbidity and mortality among Filipinos. Latest estimates show that 107 Filipinos die of TB each day (2003).

Tuberculosis is caused by Mycobacterium tuberculosis and is acquired after the inhalation of droplet nuclei laden with mycobacterium bacilli. Symptoms may include cough for more than 2 weeks, fever, weight loss, and hemoptysis. Sputum examination for acid fast bacilli (AFB) or direct microscopy is the most important diagnostic test to request for a patient clinically suspected of PTB. It is estimated that a positive test requires the presence of at least 104 bacilli per ml of specimen.

Definite diagnosis of PTB cannot be deduced from a single radiograph. Though cavitary lesions had higher positive sputum (57%) and culture yields (96%) when compared with non-cavitary lesions (12-32% and 70%, respectively), no radiologic findings were noted to consistently correlate with activity. Incorrect appraisal of disease activity based on radiographs alone was common. About 10-15% of culture positive TB patients were not diagnosed by x-ray. Forty percent of patients diagnosed as having TB on the basis of x-ray alone do not have tuberculosis. A positive PPD cannot make a diagnosis of tuberculosis disease activity in adults. A positive PPD only indicates infection , not distinguishing whether recent or remote, and not necessarily an active disease.

Tuberculosis treatment aims to cure , prevent death, prevent relapse, and prevent development of drug resistance. The basic principles of TB treatment include the following: (a) give the safest, most effective therapy in prescribed duration (b) choose multiple drugs to which the organisms are susceptible (c) never add single drug to a failing regimen (d) ensure complete adherence to therapy through DOTS. The National TB Control Program (NTP) began Directly Observed Therapy, Short course (DOTS) implementation in 1996. As of 2002, DOTS was available to 98% of the population. However , DOTS coverage within the private sector (which provides an estimated 30 to 50% of TB services) is much lower. Implementation of DOTS among private sector practitioners is very critical in reducing TB prevalence.

Tuberculosis produces pulmonary but extra pulmonary problems, as well. The course of the disease depends on the interaction between the host response and the virulence of the organism. The major defense against the tubercle bacillus is cell mediated immunity, which is effected primarily by means of macrophages and T lymphocytes. When host factors prevail, there is gradual healing. There is a tendency towards a more fulminant, disseminated and extrapulmonary disease in immunocompromised hosts. A variety of sequelae and complications may occur that may produce chronic symptoms. Hyae Young Kim,MD and co-workers has categorized these complications as follows: (a) parenchymal lesions which include tuberculoma, thin walled cavity, cicatrisation, end-stage lung destruction, aspergilloma and bronchogenic carcinoma (b) airway lesions, which include bronchiectasis, tracheobronchial stenosis and broncholithiasis (c) vascular lesions which include pulmonary or bronchial arteritis and thrombosis, bronchial artery dilatation, and Rasmussen aneurysm (d) mediastinal lesions, which include lymph node calcification and extranodal extension, esophagomediastinal or esophagobronchial fistula, constrictive pericarditis, and fibrosing mediastinitis e) pleural lesions, which include chronic empyema, fibrothorax, bronchopleural fistula and pneumothorax; and (f) chest wall lesions which include rib tuberculosis, tuberculous spondylitis and malignancy associated with chronic empyema. These various forms of sequelae and complications may result from both primary and post primary tuberculosis in pulmonary and extrapulmonary portions of the thorax. Once these complications have set in, surgical intervention may be indicated.

Parenchymal and airway lesions, namely cicatrisation, endstage lung destruction , bronchogenic carcinoma, broncholithiasis, and bronchiectasis, may produce chronic symptoms that if not debilitating may affect the patients’ quality of life.

Bronchiectasis, is an abnormality respiratory passages that may be caused by blocking of mucus. The weakened passages can become scarred and deformed , allowing more mucus and bacteria to accumulate. Symptoms include coughing, shortness of breath, abnormal chest sounds, weakness , weight loss and fatigue. Patients with bronchiectasis are often given antibiotics and bronchodilators. Daily postural drainage and chest clapping may allow patients to live a relatively normal life. Fatalities are uncommon but may result from massive hemorrhage.

Cicatrization atelectasis is a common finding after postprimary tuberculosis. Up to 40% of patients have a marked fibrotic response which manifests as atelectasis of the upper lobe, retraction of the hilum, compensatory lower lobe hyperinflation, mediastinal shift toward the fibrotic lung. Cicatrization atelectasis results from diminution of volume as a sequelae of severe parenchymal scarring.

Broncholithiasis, is a condition in which a peribronchial calcified nodal disease erodes into or distorts an adjacent bronchus. This results in airway obstruction. Broncholiths tend to be more frequent on the right side and obstructive changes particularly affect the right middle lobe. Evidence of airway obstruction including segmental or lobar atelectasis, mucoid impaction ,obstructive pneumonitis and obstructive hyperinflation with air trapping is noted.Symptoms commonly include cough , hemoptysis, recurrent episodes of fever, chest pain, dyspnea, wheezing and purulent sputum. According to Nauser et al, (Chest October 2000), patients with massive hemoptysis due to broncholithiasis are managed similarly with massive hemoptysis from other causes. No effective medical therapy for broncholithiasis is available. Not all cases require treatment,. However, if symptoms persist, either removal of the broncholith through bronchoscopy, which remain controversial, or through surgical resection may be indicated.

The DOTS clinic greatly improves the chance of the patient being cured. When treated adequately, a patient can be rendered non-infectious in as short as 2 to 6 weeks..Table 1 shows disease category and recommended treatment.

Table 1. Disease Categories and Recommended Therapy

TB Diagnostic Category	Type of TB Patient	Tx Regimen/Duration of Tx
Category I 2HRZE/4 HR	New pulmonary smear (+) cases New seriously ill pulmonary smear (-) cases with extensive lung lesions as assessed by TB diagnostic Committee New extra-pulmonary TB Concomitant HIV infection	Regimen 1: HRZE for 2 mos during the intensive phase; HR for 4 mos during maintenance phase
Category II 2HRZES/1 HRZE/ 5 HRE	Failure cases Relapse cases Return after default (smear +) Other ( smear + or smear -)	Regimen 2: HRZES for 2 mos then HRZE for 1 mo intensive phase; HRE for 5 mos as maintenace phase
Category III 2 HRZ (E)/ 4 HR	New smear (-) but with minimal pulmonary TB on radiograph as assessed by TB diagnostic committee	Regimen 3: Ethambutol may be omitted for non-cavitary smear negative, fully susceptible cases

References:
1.Nauser,Trenton , et al. , Massive hemoptysis due to broncholithiasis with fibrosing mediastinitis; Chest , October 2000
2 Snyder, Richard. Bilateral partial bronchial obstruction due to broncholithiasis treated with laser therapy; Chest Jan, 1998
3. Updates on the Management of Tuberculosis, Unilab Medical Education and Development (UMED)
4. Hyae Young Kim, Tuberculosis Sequelae and Complications of Tuberculosis, Radiographics 2001

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