Worldwide, tuberculosis of the lung is a major health problem. TB should always be considered in children from endemic areas, as well as those at risk of immunodeficiency or taking immunosuppressive agents. Once diagnosed, TB is a notifiable disease and contact tracing is required so that those exposed to the patient undergo tuberculin testing and CXR screen-ing. BCG vaccination appears to be protective against miliary spread, but is no longer routinely given.
Mycobacterium tuberculosis is spread from person to person by droplet infection. Once inhaled, some bacilli remain at the site of entry and the rest are carried to regional lymph nodes. The bacilli multiply at both sites; the primary focus along with the regional lymph nodes are collectively described as the primary focus. Organisms can then spread via the blood and lymphatics. The pathological sequence after infection is as follows.
· febrile illness;
· erythema nodosum;
· phlyctenular conjunctivitis.
· in most cases progressive healing of primary complex;
· effusion: focus may rupture into pleural space;
· cavitation: focus may rupture into bronchus;
· coin lesion on CXR: focus may enlarge;
· regional lymph nodes may obstruct bronchi;
· regional lymph nodes may erode into bronchus or pericardial sac;
· miliary spread.
· 2mths: isoniazid, rifampicin, and pyrazinamide. Often ethambutol added as a 4th drug.
· Then 4mths: isoniazid and rifampicin.
· 3mths: isoniazid, rifampicin, ethambutol and pyrazinamide.
Then 12–18mths: isoniazid and rifampicin.