Tuberculosis: What You Need to Know

This week, a man infected with tuberculosis who took two trans-Atlantic flights against his doctor's orders sparked global concern, highlighting the challenges associated with detecting and containing this potentially deadly disease.

Caused by the bacteria Mycobacterium tuberculosis, TB is spread through the air from person to person. In most cases, it is treatable with a course of medications.

But an increasing presence of drug-resistant strains — such as in this case — underscores the need for heightened efforts in containing the disease.

Doctors say that everyone from health workers to air travelers is potentially at risk of TB. But they say the best way to ensure your health is to know how the disease is transmitted, and to seek help immediately if you suspect that you have been infected.

How Common Is TB?

According to a report released by the World Health Organization in March, it appears that the rate of TB infection worldwide stabilized in 2005. However, the actual number of people who suffer from the disease is still on the rise worldwide.

There were an estimated 8.8 million new TB cases in 2005, 7.4 million of which were in Asia and sub-Saharan Africa.

Most recent figures from the WHO suggest that a total of 1.6 million people worldwide died of TB in 2005. At this rate, nearly 4,500 people die from the disease every day.

Though TB is less prevalent in industrialized countries, it is not just a disease of the developing world. Around 14,000 U.S. cases were reported to the Centers for Disease Control and Prevention in 2005.

In addition to those with active tuberculosis, an estimated 10 million to 15 million people in the United States are thought to have "latent" TB, which shows no symptoms or signs of infection. It is thought that about 10 percent of these infected individuals will develop active tuberculosis at some point in their lives.

How Does Exposure Lead to Disease?

On average, disease researchers say, it takes eight hours of contact with someone who has TB to become infected.

As the average travel time of both of the flights on which the infected man was a passenger were about eight hours, health officials with the CDC say there's a risk -- albeit small -- that people on the flight may have been exposed to the antibiotic-resistant TB.

Air filters on the plane would likely have prevented the bacteria from traveling throughout the cabin; however, the CDC has strongly recommended that people next to the passenger, two rows in front and two rows behind, get checked for the disease.

It is important to remember that not everyone who is exposed to TB develops active tuberculosis. In many cases, an individual's immune system can keep the bacteria under control for years, or even for a lifetime.

What Is Drug-Resistant TB?

As the overall number of TB cases continues to grow throughout the world, so has the number of TB cases that don't respond to conventional medications.

According to the WHO, each year there are 420,000 cases of multidrug-resistant tuberculosis, or MDR-TB, which lead to 66,000 deaths.

And in addition to MDR-TB, there is extensively drug-resistant tuberculosis, or XDR-TB. This strain is resistant not only to the two first-line drugs, but to three or more of the six classes of second-line drugs.

This XDR strain is the one carried by the man now being held in isolation.

Few, if any, of the current therapies work against this strain, making it a growing problem worldwide.

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