VOA标准英语2012--Untreatable New Forms of TB Raising Alarm

Untreatable New Forms of TB Raising Alarm

The World Health Organization (WHO) lists 69 countries that have reported what is officially called "extensively drug-resistant" tuberculosis 1 (XDR-TB). It's a form of the mycobacterium that, like the one reported in India, isn't killed by first- and second-line anti-TB injectable drugs. The WHO says at least 25,000 cases of XDR-TB are reported worldwide every year.

Dr. Margaret Chan, WHO's director-general, views the emergence 2 of drug-resistant tuberculosis with alarm.

"Call it what you may, a time bomb or a powder keg. Any way you look at it, this is a potentially explosive situation," she said.

Officials say drug-resistant TB has been a growing problem in countries such as India and China because patients are frequently misdiagnosed and often receive inappropriate or inadequate 4 treatment with antibiotics 5. Misuse 6 of these drugs increases the danger that the target pathogen will gradually develop resistance to them.

Dr. Neeraj Mistry, a public health physician, says surveys show that very few Indian doctors are actually treating TB patients with the right drugs for the right length of time.

"The emergence of totally-resistant TB is a result of failed public health intervention 7 strategies," said Mistry. "When we deliver ineffective treatment regimens and when we don't have full adherence 8 and compliance 9 to treatment, it enables the emergence of resistance within the individual."

Experts say that with the current arsenal 10 of drugs failing to hold the line against TB, the need for new drugs and compounds has become more urgent. Preventing TB through vaccination 11 is one promising 12 strategy.

"The ideal would be to develop a vaccine 13 that works in all age groups. Everyone from newborn through the elderly," noted 14 Dr. Ann Ginsberg of the Aeras Global TB Vaccine Foundation.

Ginsberg and her colleagues are running clinical trials on two TB vaccines 15 they hope will provide long-lasting immunity 16 to TB and stop transmission of the disease. If all goes as planned, she says, the vaccine will be ready by 2020.

"The clinical development program for a TB vaccine is a very long process, and it's long because, first of all, it's the nature of the disease itself - people get infected with TB and often don't get sick for years," added Ginsberg. "So when you do a vaccine trial, you have to vaccinate 17 people and watch them for years to see whether or not they will get the TB. So that makes these clinical trials very long."

While the world waits for that TB vaccine, the WHO says a new line of TB drugs - fortified 18 with a new class of potent 3 anti-mycobacterial agents - could be available by the end of this year or early next.