AIDS, drug resistance complicate TB fight

Washington -- Tuberculosis is still among the most curable infections on the planet, say those engaged in the fight against the disease. Yet it will kill more than 2 million people this year, and it infects one-third of the world's population.

Although TB is most prevalent in Asia, Africa and parts of Eastern Europe, no nation is immune in these times of high mobility.

After more than a decade of falling rates, TB's decline is slowing in the United States, according to the Centers for Disease Control and Prevention. New surveillance data show that 14,871 people with active TB disease live in the United States, the largest numbers in California, Florida and Texas. More than half of those infected are foreign-born.

Among this population, rates were nearly nine times higher than the rate of those who are U.S.-born. CDC data also indicate that disparities in TB rates persist among racial and ethnic minority populations, thus highlighting the need to target these groups for treatment.

Left untreated, each person with active TB disease will infect on average between 10 and 15 people every year, according to the World Health Organization. The ease with which the airborne infection can spread means widespread vigilance is required, stressed health officials.

"To control TB anywhere, you have to control it everywhere," said Lee B. Reichman, MD, MPH, founding executive director of the New Jersey Medical School National Tuberculosis Center, speaking to congressional staffers during a March 30 briefing.

Dr. Reichman also presented worldwide tolls from several attention-grabbing diseases to provide a dose of reality for weighing a disease's impact on public health. In contrast to the estimated 2 million TB deaths that occur annually, last year witnessed 813 deaths from SARS and 244 from Ebola. Since, Sept. 11, 2001, there have been five lives claimed by anthrax. And no deaths resulted last year from smallpox.

"TB is not a sexy disease, but it is lethal," he said.

Joint HIV/AIDS and tuberculosis infection is driving the TB death toll in many countries, particularly in southern and eastern Africa. The situation will likely worsen in eastern Europe, India and China in the years ahead, WHO reported recently.

But TB treatment is effective for those with HIV/AIDS, said Joanne Carter, DVM, legislative director for RESULTS, a worldwide organization that lobbies on a range of health, hunger and poverty issues. Dr. Carter urged congressional staffers to link U.S. funds directed toward AIDS treatment with the effort to treat TB. The effort would not be very costly, she predicted, and it would produce a large "bang for the buck."

Also troubling to those on the front lines is a recent upsurge in the number of cases that have become resistant to the two most powerful anti-TB agents in common use, isoniazid and rifampicin, said Dr. Reichman.

Cost of resistant strains

Treatment for resistant TB bacilli can take up to 24 months, as opposed to the six months generally required to treat nonresistant strains.

Treatment is also as much as 100 times as expensive, can carry side effects some equate to those of chemotherapy and requires complex diagnostics that are often unavailable in developing countries.

"Self-servingly, we have to control TB," said Dr. Reichman, pointing to Israel as an example of what can happen when large numbers of people emigrate to a nation. Israel now cares for more people with drug-resistant TB than almost any nation in the world, about 14% of new cases diagnosed from 1999 to 2002 were resistant. Many of those arrived with infections acquired in the former Soviet republics where TB is widespread.

Drug-resistant TB is caused by inconsistent or partial treatment, when patients do not take all their medicines regularly for the required period because they start to feel better, because physicians and other health care workers prescribe the wrong treatment regimens or because the drug supply is unreliable.

"Doctors are often our worst enemies," said Dr. Reichman. Treatment is often improper, especially in such settings as Soviet prisons.

A recent WHO document stressed the need to combat "super" resistant TB, or strains that are resistant to all known drugs.

However, there are some promising developments including stepped-up efforts to identify new treatments as well new vaccines and diagnostics, said Joelle Tanguy, director of advocacy and public affairs for the Global Alliance for TB Drug Development.

For example, the Bill and Melinda Gates Foundation recently gave nearly $83 million for vaccine development to Aeras Global TB Vaccine Foundation which has launched a phase II trial of one vaccine.

A new drug that has the potential for being effective against drug-resistant strains is expected to be reviewed by the Food and Drug Administration later this year for approval for testing in humans.

WHO promotes the TB control strategy known as directly observed therapy. It said the majority of the world's people live in parts of countries served by a DOTS program. DOTS ensures that the full six-to-eight-month treatment course is followed, and it has been rated as one of the most cost-effective of all health interventions.