Will rise of TB affect the U.S.?
A report found drug-resistant tuberculosis in several countries.
SCRIPPS HOWARD
To most Americans, if they think about it at all, tuberculosis is one of those relic diseases of the 19th or 20th centuries, one of myriad illnesses that became less fearsome in the age of antibiotics.
People seldom show up with TB in the medical shows on TV. No one writes self-help books for TB patients, since many of them tend to be underprivileged and abuse drugs or alcohol.
So perhaps not many people paid attention to a report from World Health Organization scientists earlier this month that concluded the extent of tuberculosis that is resistant to treatment from two or more of the most commonly-used antibiotics is greater than had been thought, and is particularly high in China, India and Russia.
Based on continuing surveillance in 79 countries, Dr. Mario Raviglione and colleagues reported in the medical journal The Lancet that they found drug-resistant TB in virtually every one of these countries, and estimate that there were 424,000 new cases in 2004, or more than 125,000 more cases than had been estimated before.
Why it's a concern
Now, that's still just a fraction of the tens of millions of people around the globe who are infected with TB every year, but the trend is worrisome, even for Americans, for several reasons.
Experts say roughly a third of the world's population is infected with TB, but in most people, the immune system keeps the germs in check.
Another recent study by French researchers discovered that TB can hide from both the immune system and the most powerful antibiotics in our fat cells, where it can remain dormant for years.
Only about 5 percent to 10 percent actually develop illness from the bacteria by having it become active in the lungs, frequently when their immune system is disrupted or damaged by the human immunodeficiency virus (HIV).
But this supposedly manageable disease killed 1.7 million people worldwide in 2004. And WHO estimates that as many as 50 million people worldwide may be infected with a drug-resistant strain of TB.
Reason for resistance
Drug resistance to TB generally occurs because patients don't stick with the drugs they're prescribed for the required six to nine months, either because they dislike the side effects of the drugs or for other reasons. Ending treatment early allows the individual TB bacilli that have natural resistance to multiply until eventually the majority of them are resistant.
If the bacteria become active and move to the lungs, a person with untreated TB typically spreads it to 10 or 15 other people each year.
It is possible to treat most strains of drug-resistant TB with more advanced drugs, but it requires taking the drugs for many months, even years, and demands that patients be closely supervised and monitored, even isolated in some cases. Treating resistant TB becomes even more complicated if patients have suppressed immune systems.
While the cure rate is 90 percent for nonresistant strains of TB, it drops to 50 percent in multidrug resistant strains.
Although the federal Centers for Disease Control and Prevention figures that about 1 percent of the TB cases in this country are multidrug resistant, and the WHO study found that incidence was declining slightly in the U.S., Americans are hardly out of harm's way.
Here in the U.S.
More than 73 percent of the multidrug cases reported in the U.S. each year occur in people who were foreign born, so if the rate of drug resistance is on the rise globally, the trend is likely to follow in this country.
Scientists have recently reported an even more extensive drug-resistant TB strain, which has been found among people also infected with HIV in South Africa.
Even in the United States, people with the most extremely resistant strains are 64 percent more likely to die than patients who had a multidrug resistant strain, the CDC says.
"Our study findings emphasize the importance of implementing sound tuberculosis control activities to prevent further creation of drug-resistant tuberculosis," Raviglione said. "Otherwise, extensive resistant-strain TB is bound to keep emerging as a fatal variant, especially in areas with high incidence of HIV."