Tuberculosis: suspicion, precautions and screening

Tuberculosis travels through the air from a patient whose diagnosis has not been made yet, so the protection a nurse gives is suspicion acted on before anything is confirmed -- a cough that has outlasted an ordinary chest infection, sputum that has turned blood-streaked, drenching night sweats, fever, and appetite and weight that have fallen away over weeks, in a patient whose history raises the risk through close contact with an infectious case, through immunosuppression and above all HIV, through crowded or institutional living, undernutrition, smoking or substance use, or through coming from or travelling to a place where the disease is common, is enough to start airborne precautions while the investigations are being arranged rather than after they return, because the patient nobody has suspected is the patient who infects people, and because the disease can settle outside the lungs and still be missed in someone whose complaint was never respiratory; the precautions themselves are a hierarchy and not a single act -- the facility triages and separates the person with signs of the disease instead of leaving them to wait among others, the patient is put in a single room with the door kept closed and the air handled as engineering provides, drawn inward and exhausted outside or filtered with enough air changes to dilute what is in it, staff put on a fit-tested particulate respirator before entering and remove it after leaving, the patient wears a medical mask whenever the room is left or someone must be close, because the mask protects everyone else from the patient rather than the patient from everyone else and gives its wearer almost no protection against particles that hang in the air, transport and procedures are kept to what is necessary and timed so that fewer people are exposed, and the treatment itself is begun promptly because a patient on effective treatment is a patient who stops transmitting; the tests are then read for what they actually report -- a tuberculin skin test read by measuring the raised induration rather than the redness, and an interferon-gamma release assay, both detect that the immune system has met the organism and neither says whether there is disease now or whether this patient is infectious, a negative result does not clear a patient whose picture fits and is least trustworthy where immunity is impaired, and prior BCG is not a reason to explain a positive result away, while what settles infectiousness is the sputum examined by microscopy and by a rapid molecular test, and what settles disease is that picture together with imaging; and the precautions come off on stated criteria -- effective treatment under way, the patient improving, and the agreed run of negative sputum results -- never because the patient looks better, never because treatment has merely been started, and never because the room is wanted for someone else, with the case notified to the health authority and the household and close contacts traced and screened so the next case is found before it spreads, and with the nurse's own protection treated the same way: assessed and tested when hired, evaluated and tested after an unprotected exposure and again after the window it takes to show, and screened for symptoms each year where a latent infection was left untreated, rather than tested over and over on a routine that no exposure ever prompted.