2009-3-24
This is the VOA Special English Health Report.
Tuberculosis killed one million three hundred thousand people around the world in two thousand seven. In addition, almost half a million people who were infected with tuberculosis and with H.I.V. also died. Those were listed as H.I.V. deaths.
An estimated one-third of all people are infected with tuberculosis. But the body's natural defenses are usually strong enough to prevent an active case. Even so, the bacteria remain in the body. If the immune system weakens at any point, they begin to spread and then attack.
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| A doctor at a clinic in South Africa looks at a patient's X-ray as part of a TB exam |
The bacteria that cause TB usually settle in the lungs. They spread through the air when the person coughs or sneezes or even sings and talks.
One of the most important things is to identify cases quickly -- especially drug-resistant cases, which are increasing. The patients need to be kept away from other people and begin treatment as soon as possible.
Multidrug resistant tuberculosis, or MDR-TB, will not get better with antibiotics normally used for tuberculosis. So doctors must use stronger, "second line" drugs when the first ones fail. Extensively drug-resistant tuberculosis, or XDR-TB, will not respond to any of those drugs but might still be treatable.
Now, researchers say they have found a much faster way to identify drug-resistant TB. The study's lead author is Graham Hatfull at the University of Pittsburgh in Pennsylvania. He says current tests can sometimes take weeks in rural and poor areas of the world. By that time, the patient may already be dead.
The scientists used viruses called bacteriophages to speed the process. These viruses attack bacteria. The researchers injected them with a gene that produces a green glow of light. They also injected some with first line antibiotics and others with second line drugs.
Then they combined the bacteriophages with TB bacteria. If the bacteria glow, it means they are drug resistant. The researchers say a clinic worker could identify the glow with equipment available in many clinics. Test results would not have to wait for the bacteria to grow in a laboratory far away.
For now, the test itself needs more testing. But Professor Hatfull is hopeful this will take months and not years.
Researchers from the Albert Einstein College of Medicine in New York also took part in the study, financed by the Howard Hughes Medical Institute. The findings appear in the journal PLoS ONE, published by the Public Library of Science.
And that's the VOA Special English Health Report, written by Caty Weaver. I'm Steve Ember.