Causes and risk factors
Mycobacterium tuberculosis bacteria enters the lungs through inhalation of droplets released into air [sneeze, cough, sputum, spit by tuberculosis infected person]. A person may remain asymptomatic even if he inhales the bacteria as it remains inactive. However a person with lowered immunity [e.g. HIV] may get tuberculosis symptoms. Droplet particles enter the periphery of lung and is engulfed by macrophages. It leads to formation of granuloma which limits the bacterial replication. Granuloma is characterised by central caseous necrosis. This forms primary lesion called as ghon’s focus. The primary lesion and involvement of lymph nodes is called as ghon’s complex. If immunity is not established secondary focuses occur via blood or lymph to other organs like kidney, liver, bones, brain, etc. causing miliary tuberculosis. Drug resistance, Immigration from high prevalence areas of TB, social deprivation, poverty, ineffective control programs, lack of access to health care are some of the predisposing factors.
Clinical presentation
TB may be pulmonary or extra pulmonary. Patient with Latent tuberculosis is asymptomatic. Primary pulmonary tuberculosis is characterised by self limiting febrile illness but clinical manifestations occur if there is hypersensitivity reaction or progressive infections. It is characterised by chronic cough, haemoptysis, low grade fever, weight loss, loss of appetite, night sweats. Anaemia and leucopoenia may be present. Post pulmonary tuberculosis include cough with haemoptysis, pyrexia of unknown origin, pleural effusion, pneumonia, pneumothroax. Progressive primary disease occurs after course of initial illness or after latent period of several weeks or months. Infections spreads via blood to form millet shaped lesions called as miliary tuberculosis. Chronic complications of post pulmonary tuberculosis consist of massive haemoptysis, obstructive airway disease. Tuberculosis may spread to other organs i.e. extrapulmonary sites causing lymphadenitis, tubercular meningitis, gastrointestinal tuberculosis, pericardial disease, genitourinary disease. New varieties of MDRTB multi drug resistant TB and XDRTB extensively drug resistant TB are becoming common.
Investigation
Medical history by the patient and Clinical examination by the doctor helps in diagnosis. Mantoux tuberculin test [though not much reliable technique] is done for screening of high risk patients. A chest x ray and multiple sputum cultures for presence of acid fast bacilli are initial evaluation methods. Clinical samples of sputum, pus, tissue biopsy are obtained for identification of mycobacterium tuberculosis bacteria. An Xpert MTD/RIF rapid, fully automated nucleic acid amplification test has been introduced recently for rapid diagnosis of TB.
Treatment
Antimicrobial or anti tubercular drugs is the treatment for tuberculosis. Multiple drug therapy is highly effective treatment. DOT [directly observed therapy] reduces the chances of relapse as it is a supervised therapy. Newer drug regimen is advised for MDR TB and XDR TB. Prevention is done with BCG vaccination at birth.
Other Modes of treatment
The other modes of treatment can also be effective in treating tuberculosis. Homoeopathy is a science which deals with individualization considers a person in a holistic way. This science can be helpful in combating the symptoms. Similarly the ayurvedic system of medicine which uses herbal medicines and synthetic derivates are also found to be effective in treating tuberculosis.
Recent updates
MDR TB i.e. multi drug resistant TB is a form of TB that is not responding to the standard treatment which is hampering efforts for control and management of TB. It is also threatening WHO’s target for elimination of TB by 2050.
Facts and figures
2 billion people – one third of world’s population are infected with TB bacilli. TB is curable but kills 5000 people every day. Global TB incidence is growing at 1% every year because of the rapid increase in Africa. Africa carried greatest proportion of MDR TB. In 2013, 9 million people fell ill with TB; an estimated 4, 80,000 people developed MDR TB; number developing MDR TB tripled between 2009 and 2013. 1.5 million died with TB among them 5, 10,000 were woman. TB death rate dropped 45% between 1990-2013. 22 countries showed sustained decline in TB cases over the past 20 years. Extensively drug resistant TB – XDR TB has been reported by 100 countries in 2013. On an average 9% of people with MDR TB have XDR TB.
