Travelers Carry TB Worldwide
By Robert Preidt - HealthSCOUT Reporter
If you travel for extended periods to countries with high rates of tuberculosis (TB) your risk of becoming infected with the TB bacterium is about equal to that of the native population, Dutch researchers say.
And people who return home infected with TB risk reestablishing the disease throughout countries that now enjoy extremely low TB rates, warn the same researchers.
A study out of Holland examined 656 Dutch travelers before and after visiting places like Central America, sub-Saharan Africa and Southeast Asia where the annual rate of TB infection is at least 1 percent. Travel stays ranged from three to 12 months.
Twelve of the 656 travelers, or 1.8 percent, returned home infected with the Mycobacterium tuberculosis bacterium. Health-care workers were 3.7 times more likely to have become infected with the TB bug than non-health-care workers.
Results of the study appear in the Aug. 5 issue of the British medical journal The Lancet.
TB is responsible for between 2 million and 3 million deaths around the world each year. Most people infected with M. tuberculosis have latent TB. That means they carry the germ but do not have symptoms of illness.
In some people, especially those with weakened immune systems, the TB germ can become active. This is called TB disease and it can result in damage to the lungs and other organs. It can also cause death if not treated with appropriate medications.
It's when TB is in its active phase that the germ can be spread to others, usually through a patient's cough, which sends TB germs airborne for others to breathe.
Rates higher than thought
Dr. Frank Cobelens, lead author of the study, says gathering data of this sort is vital because it forms the basis of prevention policies. "Until now we had no idea about the quantity of the risk for travelers to get infected with TB," he says. "In this case I think TB is an infection worth paying attention to. The [incidence rates] were higher than we expected."
Cobelens says a list issued last month by the Centers for Disease Control and Prevention profiling people at high risk for TB does not include travelers. But he thinks it should.
"The risk is much larger for people who travel," says Cobelens. "This means travelers could contribute to the pool of latent TB infections in low incidence countries."
Dr. Lee Reichman, a tuberculosis expert at the New Jersey Medical School in Newark says that having an excellent TB control plan in the U.S. and other industrialized countries only goes so far.
"We've been doing a spectacular job of controlling TB in the U.S.," says Reichman. "But to protect against TB anywhere, you have to prevent it everywhere, and this study makes that conclusion even more apparent."
Reichman would like to see more U.S. dollars spent to fight TB in poorer countries. "TB is the largest killer of any single infection worldwide," he says. "Controlling TB overseas controls TB in the United States. So our efforts [to battle TB abroad] are really self-serving and we shouldn't be ashamed of that."
Thanks to antibiotics developed in the 1940s, TB was thought to have been virtually wiped out by as little as 20 years ago. But cases have been on the rise across the globe due mostly to the effects of HIV on people's immune systems.
A small number of TB strains have developed resistance to certain antibiotics. In these cases, combining different antibiotic drugs has proven effective.
What To Do
In you're planning a lengthy stay in a country with high rates of TB, then getting a skin test before and after your travels is an excellent screening tool, says Reichman.
Both latent TB and active TB disease can be treated with antibiotics. However, the earlier you see a physician the better because treatment for latent TB will prevents M. tuberculosis from becoming active later on.
A vaccine for TB called BCG is also available, often as part of an immunization cocktail for 5 or 6 other diseases. According to Reichman, however, its effectiveness is seriously in question. So talk to your doctor about this option before making any decisions about strategies to lower your TB risk.
To learn more about tuberculosis, visit the New Jersey Medical School online. Another source of tuberculosis information is offered through the Columbia University Department of Informatics.
SOURCES: Interviews with Frank G.J. Cobelens, M.D., Ph.D., epidemiologist, division of infectious diseases, tropical medicine and AIDS, Center for Tropical and Travel Medicine, Academic Medical Center, Amsterdam, Netherlands; and Lee B. Reichman, M.D., executive director of the New Jersey Medical School National Tuberculosis Center, Newark, N.J.; Aug. 5, 2000, The Lancet

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