TAILIEUCHUNG - PULMONARY TUBERCULOSIS IN ADULTS

M. tuberculosis is carried in airborne particles, called droplet nuclei, of 1–5 microns in diameter. Infectious droplet nuclei are generated when persons who have pulmonary or laryngeal TB disease cough, sneeze, shout, or sing. Depending on the environment, these tiny particles can remain suspended in the air for several hours. M. tuberculosis is transmitted through the air, not by surface contact. Transmission occurs when a person inhales droplet nuclei containing M. tuberculosis, and the droplet nuclei traverse the mouth or nasal passages, upper respiratory tract, and bronchi to reach the alveoli of the lungs (Figure ) | SECTION 5 CLINICAL PRESENTATIONS OF TUBERCULOSIS CHAPTER 29 Pulmonary tuberculosis in adults Christopher J Hoffmann and Gavin J Churchyard BACKGROUND The World Health Organization WHO defines pulmonary tuber culosis TB as tuberculous disease that involves the lung paren chyma. Tuberculosis involving the trachea is often also included in the definition. Extrapulmonary TB is disease involving any part of the body other than lung parenchyma including other structures within the thorax such as the pleura pericardium and perihilar lymph nodes. This distinction is most important from a public health per spective because patients with untreated pulmonary TB pose an infectious risk to the rest of the community whereas the risk to the community from extrapulmonary TB is minimal. Thus patients with pulmonary TB who also have extrapulmonary involvement are clas sified as cases of pulmonary TB by the WHO. In addition to classification by location TB has traditionally been classified as primary or postprimary disease. Primary infection includes the symptoms and complications arising from the first con tact between host and the bacillus and is most clearly defined by conversion from a negative to a positive tuberculin skin test TST . In the minority the primary complex results in local progression or distant disease in the majority the complex resolves. Postprimary TB disease usually follows the primary infection by years occurring through reactivation or reinfection. Other nearly synonymous terms with postprimary TB include reactivation TB recrudescent TB endogenous reinfection and adult type progressive TB. In years past primary TB was considered a disease of children and post primary TB a disease of adults. In the era of human immunodefi ciency virus HIV distinctions between primary and postprimary TB have become increasingly blurred as primary TB is often seen in HIV infected adults. This chapter focuses on the clinical presentation of pulmonary TB and its complications. The

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