Tuberculosis - Not a Dying Disease 肺結核從來沒有消失

Pulmonary tuberculosis is an infectious disease caused by slow growing bacterial species known as Mycobacteria. The name of this germ is borrowed from its characteristics of slow growing, indolent and can present as spore keeping bacteria alive in long term in adverse temperature and humidity condition similar to fungus. The air borne ability of the mycobacteria spore give it as much infectious concern as influenza. However, the man to man transmission ability is far lower than virus. Also the amount of infectious load is much higher than virus to cause clinical disease. For example, exposure to droplet transmitted virus like measle may cause successful disease transmission if only ten or a little more viral particle is inhaled by susceptible individual. In tuberculosis, intense exposure to hundreds of spores may not end up in clinical disease. However, as mycobacteria tuberculosis is ubiquitous in most human inhabitated area. Avoidance of it is much difficult.

Tuberculosis is still endemic disease in Hong Kong. Although treatment of such disease has made so much advancement that curing this disease is now mainly an out-patient managment problem.  A few decades ago, if young men or women has been infected with tuberculosis, the treatment of such is still old fashioned resting and sunlight and good nutrition. Housing in a sanatorium or convaslescent environment is only method to prevent spread of disease in densely potpulated cities. Paradoxically this air borne bacteria has much less infectivity potential if high ceilings, good ventilation and well space out beds in room with natural ventilation.  Few staff in such sanatorium will be infected due to working environment unless the nurse or doctor has overworked too much to have low immunity.

Are healthy individual always resistant to tuberculosis?  The answer may be yes and no. For malnourished and alcoholic, reactivation of tuberculosis and primary infection is likely. But for healthy individual, reaction to latent tuberculosis may be  exaggerated causing destruction of lung or granuloma formation.  Reactivation of tuberculosis or persistent of infection may also related to hormone, age and genetic make up.

Nowadays treatment of tuberculosis is effective and comprehensive. Different class of drugs has good effect on it. Investigation to underlying immune deficiency is necessary but rarely postive in endemic area like HK. But confusion with lung cancer shadow is much of a concern too. Therefore, if lung shadow has shown poor response to antituberculosis chemotherapy, excision biopsy is necessary in high risk individual like smokers of patients with strong family history of cancer.

Hong Kong has good system of treating pulmonary tuberculosis. Chest clinic offer walk in CXR and consultation if persistent cough for more than 2 weeks.
Supervision of tuberculosis treatment ensure good compliance. Expert of tuberculosis are easily found in governemnt services.

Sometime, thoracic surgeon may encounter cases mimmicking lung cancer. Final pathology turn out to be tuberculosis. The patient may be complaining about that. However, for lesion as big as a pseudo tumour, it is essential to remove it surgically even if good response to tuberculosis is found. Because if the lesion is left, confusion with later lung pathology or causing hemoptysis or bronchiectasis change may be as harmful as cancer itself.
For fit individual removal of granuloma of destryoed lobe by tuberculosis give better quality of life. Of course, to high risk indivdual lke patient with significant coroanary disease or renal failure, option for medical treatment alone is better suited then.