Tuberculosis: What You Need to Know

May 30, 2007 — -- 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.

In fact, the number of countries in which XDR-TB has surfaced has recently nearly doubled from 19 to 35 in a single year. Some of these outbreaks have occurred in European nations.

Worse, while the test for TB infection takes several days at most, the test to determine infection with XDR-TB can take between six weeks and 16 weeks, according to the CDC.

How Do I Know If I Have TB?

The most common symptoms of tuberculosis are fever, chills, night sweats, weight loss, fatigue, loss of appetite and coughing up blood.

Since most of those exposed to the disease will first pass through a latent phase, they will usually be symptom-free shortly afterward, and they will not be contagious during this time.

If you think you may have been exposed to tuberculosis, you can visit your doctor for a skin test that will reveal in 48 hours to 72 hours whether you have been infected.

If the test is positive and you do not have symptoms, your doctor will prescribe a course of medications that you will take over the next nine months or so. These medications decrease the chance that you will get active tuberculosis in the future.

If your doctor believes that you have active tuberculosis, you will most likely be hospitalized and placed in an isolated room while doctors conduct further tests.

The isolation period for preliminary tests is at least three days, but it can stretch to two weeks or more if your test results are positive.

Is TB Curable?

In most cases, the answer to this question is yes. Treatment for active tuberculosis consists of four drugs to be taken anywhere from four months to a year, or even longer.

However, resistant strains of tuberculosis such as XDR-TB cannot be treated with regular medications. Even when these patients are treated with the best medications available, half of people with MDR-TB, and almost all with XDR-TB will die.

So far, these resistant infections have been very rare in the United States. The best way to avoid resistant TB is to make sure that everyone with TB gets the full course of appropriate treatment.

If you or someone you know has been exposed to tuberculosis, or has any of the symptoms discussed above, you should contact your doctor or the local health department to get tested.

Reports from Dr. Sami Beg and Beata Casanas contributed to this piece.