What is Tuberculosis?
Tuberculosis is an infection, a bacterium called "mycobacterium tuberculosis," behaving much like a persistent pneumonia. Though once a major killer around the world, the use of antibiotics had significcantly reduced its occurrence in America. However many social changes (AIDS, older population, homeless people, immigrant crises) have borugh about a resurgence of new cases of TB.
Most cases of T.B. are actually reactivations of infections acquired in the distant past. At the time of the primary exposure, the infected droplets from the sputum of an active case are breathed in, and deposited in the lungs where they rarely cause significant disease, and are successfully contained by the body's defenses. Some cases of primary exposure are serious (especially in young children) but this is unusual. Only years later, perhaps during a time of physical stress, aging, debility, or ingestion of an immune suppressing drug, does the active disease reappear.
Most cases of tuberculosis appear slowly, over weeks or months, although an occasional case of sudden pneumonia or spinal infection may be seen rarely. Weight loss, fever, night sweats (many of the symptoms of some cancers as well) are common. A cough productive of sputum and sometimes blood is a later sign, as are chest pain and breathlessness. In some cases, the germs will have spread to other organs, including the kidneys, brain, liver and almost any other location. Swollen lymph nodes are often seen. Because of the diverse and unpredictable nature of the disease, it can be exceedingly difficult to diagnose if not considered directly.
Diagnosis:
If the symptoms are mostly respiratory, a chest x-ray is often the best clue to diagnosis, as the germ causes highly typical changes in the lungs.
Cultures of the sputum is the primary method of diagnosing active TB of the lungs. Sometimes specimens from the lung must be obtained by bronchoscopy. Elsewhere in the body, a biopsy or culture of some body fluid is often the only means of diagnosis. Often the physician is surprised to find tuberculosis. Persistent and unexplained pus or white cells in the urine on rare occasions is caused by tuberculosis, as is intestinal infection.
More commonly, tuberculosis is diagnosed some time between exposure and symptom occurrence by means of a simple skin test applied routinely to patients under age 35. A positive test indicates prior primary infection, although all signs of the disease are usually absent, and even the chest x-ray is normal. This represents the mildest form of the "disease," and is easily treated with a course of antibiotics to prevent furhter disease. In many cases treatment is not even necessary. The skin test may miss an occasional case, as it is blocked by even trivial intercurrent viral illness or other common fevers and illness. In addition, the test may rarely be falsely positive from past exposure to germs similar to tuberculosis, but of no medical concern.
The untreated patient with active disease (as opposed to inactive infection or simple exposure) may develop progressive weakness, spreading infection, organ involvement and death. The slow but relentless course has led to the archaic but apt term "consumption." Occasionally, bizarre and complex symptoms may occur, and alternate diagnoses such as depression or cancer are entertained for long periods before the correct diagnosis is made.
Treatment:
There are numerous drugs available to treat tuberculosis in virtually any stage and, properly managed, well over 90% of patients should be cured.
Unfortunately the courses of treatment for this slow growing germ are prolonged, ranging from 9 to 24 months. The ideal treatment setting is the office, and the ideal patient to treat is the one whose only manifestation is a routinely detected positive skin test, with a negative chest x-ray. In this event, the usual treatment is the drug isoniazid, given for one year. This reduces the risk of later active infection to the minimal level possible, is quite safe, inexpensive, and rarely causes side-effects.
Health care workers and others at risk may continue to receive skin testing indefinitely. Complicated decisions weighing the relative risks of treating inactive disease versus risk of treatment itself are beyond the scope of this discussion, but may vary widely. In actively ill patients there is no disagreement that treatment is indicated and quite effective. One of the biggest problems is getting patients to comply with their doctor's advice for 18 months of therapy. In active disease, combinations of isoniazid, rifampicin, and ethambutol (usually the first two) are commonly used, and the trend is toward shorter course of around 9 months. In any event, careful follow-up and repeat cultures are important.
Tuberculosis has become, within this century, a highly curable, easily detectable, and usually mild disease, compared to the monstrous and inexorable consumption of yesterday. The biggest obstacles preventing eradication of the disease entirely are the failure of patients to seek medical care in a timely fashion, to comply with medical regimens, and to obtain careful follow-up surveillance, as well as the societal problems which allow these circumstances to persist and the inevitable shortcomings of some members of the medical community who manage the disease.
