Tuberculosis: Still Striking

by Food and Drug Administration (FDA)

A general practitioner, now retired, recalls his early experiences as an intern in a Washington, D.C., hospital after World War II: "At that time, all the interns had to do a rotation in the TB annex, where there were six floors of very sick people. They did a lot of surgery in those days to remove diseased lungs, a lot of pneumothorax [artificial collapse of a lung to allow it to heal]. Besides good hospital care, there wasn't a great deal more we could do for tuberculosis patients."

The TB annex no longer exists. The building still stands, but the rooms were turned over long ago to patients with more pressing medical problems.

But the problem of tuberculosis, dormant for a number of years, is beginning to worry public health officials again. Out of a population of approximately 250 million Americans, the nearly 24,000 cases of tuberculosis reported in 1989 to the U.S. Centers for Disease Control in Atlanta, Ga. doesn't sound like a particularly scary statistic. What concerns public health authorities is that after decades of declining figures — 22,201 cases in 1985, the lowest annual total in 60 years — the number of TB cases has slowly begun to creep up again. Society's problems — AIDS, poverty, homelessness, alcohol, and drug abuse — and other factors are reversing the previous downward trend and reviving memories of the days when TB was a major health threat.

In the 19th century, this formidable enemy claimed more lives in this country than any other disease. The number of Americans who contracted TB declined sharply after 1900 due to a better understanding of the disease and improved hygiene, but the death rate was still high: TB was responsible for 5 million deaths in the first half of the 20th century. As late as 1954, more than 110,000 beds were devoted to the care of TB patients alone in the United States. With a few exceptions in research institutions, today there are none.

The great TB sanitariums, such as those in Saranac Lake, N.Y., and Glen Lake, Minn., shut their doors forever to TB patients in the 1950s and 1960s. These institutions and others like them both here and in Europe were established in the late 19th and early 20th centuries to combat a disease for which the only known treatment was a regimen of fresh air, nutritious diet, and bed rest. The theory was that given half a chance, the body would fight the disease itself. It worked for some of the people fortunate enough to be able to stay in these "magic mountains," as writer Thomas Mann called them, but more died than lived.

The discovery of streptomycin in 1944 and isoniazid (INH) in 1951 made the long, expensive "cure" unnecessary and put TB sanitariums and hospitals out of business. It was at last possible to successfully treat a disease — in most cases at home rather than in the hospital — that had been around since prehistoric times.

Airborne Transmission

TB is usually caused by repeated exposure — usually at home or at work — to droplets contaminated with tubercle bacilli (a species of rod-shaped bacteria) that are expelled into the air when a person with active pulmonary TB coughs, sneezes, or even sings, speaks or laughs. The TB bacteria (Mycobacterium tuberculosis) in these excretions are so tiny that they dry out and float on air currents and may survive for long periods in an enclosed space.

Contrary to popular belief, TB is not likely to be transmitted through personal items belonging to those with TB, such as clothing, bedding, or other items they have touched, according to the American Lung Association.

Even when exposed to TB, most people who breathe in the bacteria don't become infected. Of those who do, most don't develop active disease; instead, the TB bacilli may lie dormant in the cells lining the lungs' air sacs, where the body may wall them up in tiny, hard, grayish capsules, or tubercles. (TB can spread to other parts of the body, but the most common site is the lungs.) From then on, a lifelong balance between the infection and the infected may be maintained. If the body's resistance is lowered because of aging, illness, fatigue, malnutrition, alcoholism, or other factors, this balance may be upset, allowing bacteria to break out of the tubercles and enter the bloodstream, causing active TB.

It is estimated that 10 to 15 million Americans are among the 1.7 billion people worldwide who are TB carriers but are not infectious to others. About 90 percent of TB cases in this country occur when a dormant infection awakens and develops into active TB; only 10 percent result from a newly acquired infection. Of all infected people, 5 percent will develop the disease within a year, while another 5 percent will develop TB later on in their lives.

TB experts still don't know why most people who have been infected with the TB organism don't ever develop active disease, why some people develop active disease immediately, and why most cases occur among people who became infected earlier.

TB Cases Rise

The current epidemic of the human immunodeficiency virus (HIV) is one of the main reasons for the increase in new cases. People with both TB and HIV infections are at substantially greater risk of developing active tuberculosis than are people infected with the TB organism but who are not HIV-infected. The World Health Organization estimates that worldwide, about 3 million people with HIV infection are also TB-infected. Those with HIV infection who come from areas where TB is endemic, such as parts of Latin America, sub-Saharan Africa, and southeastern Asia, are at high risk for TB.

The growing numbers of homeless are also contributing to rising statistics. Up to 6.8 percent of America's homeless have active TB, and about 50 percent have latent TB infection, according to CDC. Observers say, therefore, that homeless shelters may provide a fertile breeding ground for the disease.

About the Author

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