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Until only a few decades ago, tuberculosis (TB) was one of the most dreaded diseases in the United States and around the world. Its victims suffered slow, painful deaths from respiratory failure or from an infection their weakened immune systems could no longer resist. The only recognized treatment was rest in “sanitariums,” special hospitals set up in rural areas where TB patients could breathe clean air and be isolated from the uninfected population.
The introduction of penicillin, the first modern antibiotic, in the 1940s was a major victory in the war against TB. This was the first drug that could actually kill Mycobacterium tuberculosis and restore TB patients to health. Since then, the disease has been successfully treated with a combination of four newer antibiotics - isoniazid, rifampicin, pyrazinamide and ethambutol - taken over two months, followed by a four-month treatment with isoniazid and rifampicin alone.
Drug treatment initially was very successful. The death rate from TB in New York City, once a hotbed of TB infection, plummeted from 197 deaths per 100,000 people at the turn of the century to only two deaths per 100,000 people in 1980. The number of newly reported cases of TB nationwide fell from 135,000 in 1947 to 22,000 in 1985.
But just when TB seemed to be heading the way of smallpox and polio into mankind's distant memory, the disease began to resurface with a vengeance. By 1992, the number of new cases in the United States had climbed to 30,000.
The World Health Organization (WHO), which in 1993 declared a global TB emergency, estimates that the disease claims nearly 3 million lives each year, more than any other infectious disease.
The forms of TB seen today, from the poorest developing countries to New York and other U.S. cities, are far more virulent than the forms treated so readily with penicillin a half-century ago. Even the newer, stronger antibiotics are proving to be no match for the disease. Multidrug-resistant TB is spreading throughout the world and accounts for nearly half the new cases and most of the relapses seen in the United States.
Multidrug-resistant TB is the product of incomplete treatment of infected individuals. Because patients usually feel better soon after beginning treatment, they may be tempted to stop taking their drugs before they have killed all the bacteria, often selling the expensive medications or giving them to sick family members. Patients who interrupt their treatment enable the most drug-resistant TB bacteria to survive and grow in their bodies, and go on to infect other people.
Ironically, it was the earlier victory against TB that fueled the disease's return in the 1980s and '90s. After the introduction of modern antibiotics, attention shifted to chronic diseases such as heart disease and cancer, and resources to fight TB dried up. By 1988, New York City's TB control budget stood at only $4 million, a tenth of the 1968 level.
“There are basically three reasons for TB's return to New York and other cities,” says Barry R. Bloom, an expert in TB research at the Howard Hughes Medical Institute at Albert Einstein College of Medicine in the Bronx. “The first is AIDS, which causes immunosuppression, making it far more likely that people infected with TB will develop active disease. The second is the disintegration of social structures and the resulting homelessness and overcrowded conditions in shelters, which are as good a way as any to make TB happen. The third is the crumbling of our public health system, especially the cessation of federal funding of state TB control programs in the early 1970s.”
Although there are other ways to combat TB, the most effective is directly observed treatment of individuals who already are infected with the disease. This approach, first used in Tanzania in 1977 and recommended by the WHO, requires health workers to watch their patients swallow each dose of medicine every day for at least the first two months, and preferably all six months, of treatment.
Widely publicized outbreaks of multidrug-resistant TB in New York hospitals and prisons in the late 1980s prompted the CDC and other agencies to renew funding for TB control in 1989. New York's TB program hired additional outreach workers to follow up each case for the duration of treatment and offered incentives such as subway tokens and food vouchers to encourage patients to participate. Today, nearly 40 percent of New York's TB patients are undergoing directly controlled treatment, compared with a national average of only 17 percent, and the incidence of TB in the city has already started to decline, falling by 15 percent from 1992 to 1993.
The CDC counted 24,361 new cases of TB nationwide in 1994, almost 4 percent fewer than in 1993. But public health experts worry that recent progress against TB may hold the seeds of its resurgence unless the renewed attention to the disease is permanent.
“Every so often there's a disaster that makes people take notice,” says Stephen S. Morse, a virologist at the Rockefeller University in New York City. “Suddenly we're back there doing surveillance of TB again, but we're always behind the need. The crisis appears, and then we respond to the crisis, which is not really a proactive response, nor is it efficient. Like everything else we do in infectious diseases, once the immediate crisis is over the system becomes a victim of its own success.”
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