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112: INVISIBLE ENEMIES
room with the doors and windows shut tight against drafts. When he was twenty-three, he did the same for his youngest brother. In those long hours, Keats both breathed in countless numbers of Mycobacterium tuberculosis, the germ that causes the disease, nad learned firsthand the details of how he himself would die.
It has been estimated that in Keat's day, the beginning of the nineteenth century, one quarter of all Europeans died young of tuberculosis. At that time, the creative were considered especially vulnerable: one could hardly claim to be an artist without a bloody handkerchief. The poet Lord Byron, who did not have the disease, once went so far as to wish he could die of tuberculosis because, he said, the ladies would all say, "Look at that poor Byron, how interesting he looks in dying!"
Of course, once Byron was dead, the ladies would not matter, but part of the allure of tuberculosis was that dying went on for years: the thin, flushed, and feverish look was considered roman-tic, and one was not always too sick to enjoy being so perceived. But this slow, creeping death is also what has made tuberculosis so terrible. Like its relative leprosy, tuberculosis reproduces much more slowly than most germs. This made it difficult to diagnose, concealed the fact that it is contagious, and made it hard to study in the laboratory. Tuberculosis is stealthy: after it enters a body, the germ will wait as long as it takes, ten days or fifty years, for the moment the host is weak enough to attack. When tuberculosis does attack, the infected person feels tired, gradually more and more so, but does not know why. Tuberculosis gives no outward sign of its presence until too late. before we learned how to probe the body for evidence of the disease with X rays and skin tests, the bright red spot of coughed-up blood was the first definitive sign, and by then tuberculosis was well established.
More than five decades after a cure for the disease was found, tuberculosis, known as TB for short, kills more people than any other single germ besides HIV. It is the largest single cause of death from infectious disease in the United States. Worldwide, two million people die from it each year; over eight million become infected. In little more than the time it takes you to read this sentence, another person will die of TB.
HIDING PLACES
The doctor who rushed to Keat's bedside that snowy evening could do very little. Both doctor and patient understood that the bright red color of blood on the pillow meant it was oxygen-rich blood from an artery, freshly bleeding into the lung. But nei-ther could tell for sure how badly damaged the lungs were, or what caused them to bleed so. The doctor could order no X rays, and he did not even have a stethoscope in his bag to explore the lungs sucking air into Keat's thin chest. The stethoscope had just been invented and was still considered and eccentric instrument. To examine the lungs, the doctor could either place his cold ear against Keat's hot, feverish chest and listen, or he could tap on Keat's skin, moving down each side of his chest in a line of taps, until he heared the hollow drumlke sound of healthy lungs give way to a dull thud where the lungs were too congested to breathe.
From this examination he concluded that the poet's lungs were fine. The germ fooled the doctor, even it it did not fool Keats. The doctor pulled out his surgical lancet, pierce Keat's arm, and applied the current therapy for such a fever: he allowed Keats to bleed. In fact, this treatment could only have further weakened Keats's body and helped tuberculosis along. The doctor could not find and attack the tiny enemy Keats breathed in years before.
The rod-shaped bacilli that cause tuberculois, each just two millionths of a meter long, can travel comfortably in the tiny moist particles that ride in one's breath. These droplets, carrying one to three bacilli each, are small enough to float in the air and