TB declines in United States, but fight escalates globally

Control efforts are hampered by long treatment regimens and the difficulty of convincing people to be screened after exposure.

By Victoria Stagg Elliott, amednews staff. April 16, 2001.

When two suburban Chicago residents were recently diagnosed with tuberculosis, James Gallai, MD, executive vice president of field operations of the Suburban Cook County Tuberculosis Sanitarium District, sent in the ground troops. Their mission: to screen the other 1,000 residents of the building where the TB patients lived. Dr. Gallai's organization sent out mailings, set up on-site clinics and laid out donuts to try to attract neighbors' attention.

In the end, only 37 out of 1,000 people showed up. Dr. Gallai's organization has certainly had other, more successful attempts, most commonly in workplaces where the employer requires screening. But this case illustrates one of the biggest difficulties of eliminating TB, he said. People don't think they are at risk.

TB totals
Links

There are about 20,000 cases of active TB annually in the United States, a number that has been declining about 7% a year since 1992. Another estimated 10 million to 15 million people carry TB, with a 10% lifetime risk of developing the active form of the disease. This risk increases significantly if the immune system is compromised by HIV or other factors.

As in the rest of the country, the number of cases in Chicago declined significantly in 1999, according to statistics released at a March hearing held in honor of World Tuberculosis Day. But, warn public health officials, it also plunged in the 1960s and 1970s, only to reemerge in the late 1980s and early 1990s, spurred on by a lack of efforts to control the disease and the emergence of HIV and AIDS.

"We could pat ourselves on the back, stop paying attention and move on and let TB control efforts fade into the background," said Bill Paul, MD, deputy commissioner for communicable disease with the Chicago Dept. of Public Health. "The problem is that the last time we did that, it didn't work and TB came back."

According to an Institute of Medicine 2000 publication, Ending Neglect: The Elimination of Tuberculosis in the United States, the nation is at a critical junction in the fight against the disease. Elimination is feasible, the study said, but more aggressive and decisive action will be required, and new tools are needed to improve diagnosis and treatment.

"This country has entered a dangerous phase in which the disease has retreated to specific communities where it can lie dormant and resist detection," said Morton Swartz, MD, chair of the IOM group that wrote the report. "Without decisive steps to identify and treat the undetected case, the disease could come back with a vengeance and exact a heavy price."

Efforts to eliminate it, though, are stymied by long, complicated treatment regimens, inefficient screening techniques that have not changed in decades and an influx of new infections from overseas.

Treatment for active tuberculosis can involve a patient's taking as many as 16 pills a day for as long as a year. Half-treated cases may mean the patient is contagious longer, can infect more people and can develop drug-resistant infections. Public health departments usually arrange for therapy to be observed by a health care professional. In some cases, though, this requires steps including court orders and cash payments to convince people to finish their medicine.

"Directly observed therapy is expensive but it's effective," said John L. Wilhelm, MD, MPH, commissioner of the Chicago Dept. of Public Health. "But shorter courses of medicines would make it much easier."

Screening, if you can get people into the clinic, is also far from efficient. A skin test can result in a false-negative if the person has recently been infected or is immunocompromised. There are also no tests to distinguish between those who will progress to the active form of the disease and those who won't.

"Existing diagnostic tests are slow, cumbersome and often expensive," said Gordon Perkin, MD, director of the Global Health Program at the Bill and Melinda Gates Foundation, in a statement. "We need tests that are low cost, with high sensitivity, and that can be used in the field." The foundation awarded $10 million to the World Health Organization specifically for the development of new diagnostics.

"Tuberculosis is a global problem," said Dr. Gallai. "And when we reduce it overseas, we will reduce it further here."

As is the case with 40% of U.S. cases, the two people with TB in the Chicago suburb were foreign-born. Although domestic numbers for TB have gone down, the same is not true in the rest of the world.

According to the WHO, the number of TB cases globally increased to 8.4 million in 1999, up from 8 million in 1997 -- an increase accounted for by the 20% growth in incidence in Africa. Ninety percent of cases occur in developing nations.

In an attempt to lower these numbers, the organization recently launched the Global TB Facility to procure TB drugs for countries that cannot afford them and to improve adherence to its directly observed therapy, short course -- DOTS -- program.

DOTS, meant to be a blueprint for controlling the disease, is controversial. Critics charge that the direct observation requirement is so time intensive, costly and disruptive to patients' lives that it may actually make compliance less likely.

Most recently, a study published in the March issue of The Lancet examined tuberculosis patients in Pakistan and found similar cure rates between those patients whose therapy was directly observed vs. those who self-administered treatment. Although the researchers conceded that observation was good for some, they questioned whether it was good for all.

Nonetheless, Canada has already agreed to provide $10 million of the $50 million annually that the WHO says it needs for the program.

In the United States, legislation was introduced in the House of Representatives in March that would provide $260 million for global TB control efforts. Additional legislation calls for new funding for the TB control activities at the Centers for Disease Control and Prevention as well as expansion of TB research efforts at the National Institutes of Health.

Many say, however, that what is missing is the private sector. Medication and screening technologies for TB have hardly changed in decades.

"Because tuberculosis was decreasing, there hasn't been much interest from commercial pharmaceutical companies either in developing new antibiotics or vaccines," said Dr. Swartz. "Commercial companies want growth diseases that they can make a profit on."

ADDITIONAL INFORMATION:

TB totals

10 million to 15 million - People in the United States who may have latent tuberculosis
10% - Chance those with latent tuberculosis will develop the active, communicable form of the disease
18,361 - Active cases of TB in the United States in 1998
1.1% - People with multidrug-resistant TB in 1998
31% - Decrease in TB from 1992 to 1998

Source: Centers for Disease Control and Prevention