- 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
- 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
- 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
- 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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