The New York Times - September 5, 2006
Lawrence K. Altman

The meeting in Johannesburg on Thursday and Friday is being held in response to recent reports of a small but growing number of cases of the deadly strains, known as XDR-TB (for extreme drug resistant tuberculosis).

"XDR-TB poses a grave public health threat, especially in populations with high rates of H.I.V." with few health care facilities, the health organization, a United Nations agency, said today.

The meeting will include officials from South Africa, from other African countries and from the United States Centers for Disease Control and Prevention. The goal is to help South Africa control an outbreak that has killed 52 of 53 patients with XDR-TB and that was reported at the International AIDS Conference in Toronto last month. The deaths occurred on average within 25 days, even in those patients who were taking anti-retroviral drugs.

The resistant strains have been identified in all regions of the world in recent months, most often in Asia and countries of the former Soviet Union.

The meeting also aims at determining whether some marketed drug, or a new combination of standard drugs, can be identified to still be effective against XDR-TB.

Tuberculosis experts do not know what gave rise to the XDR-TB outbreak in Tugela Ferry in rural KwaZulu-Natal Province, but misuse of anti-tuberculosis drugs is the most likely explanation, said Paul P. Nunn, a W.H.O. tuberculosis expert who is expected to be at the meeting.

"Whatever the practice is, it must be changed," Dr. Nunn said.

Dr. Mario C. Raviglione, who directs the World Health OrganizationÆs tuberculosis program, said in an interview that "nobody at the moment can be considered an expert" about the XDR-TB problem.

But he said that the XDR-TB situation is "extremely scary."

When the U.S. Centers for Disease Control last year asked tuberculosis labs worldwide to take a look at specimens for XDR-TB, the results were alarming.

In a paper published this summer in Morbidity and Mortality Weekly, researchers reported that 15 percent of samples in South Korea had extreme drug resistance, 19 percent in Latvia, as well as 14 percent in the East European/West Asia region. In the United States, 4 percent of sample were XDR.

"XDR TB has emerged worldwide as a threat to public health and TB control, raising concerns of a future epidemic of virtually untreatable disease," the researchers said.

Extreme drug resistance is defined as strains of tuberculosis that are impervious to at least 3 of the 6 second-line drugs available to treat TB, and some are impervious to all 6.

The officials at the W.H.O. meeting will also try to identify and recommend the best ways to handle the disease, possibly including these approaches:

* strengthening standard measures like use of masks, gowns and other measures to protect health workers from acquiring XDR-TB and prevent further spread of the strains.

* improving steps to ensure prompt diagnosis and treatment of tuberculosis cases and monitoring the incidence of new XDR-TB infections.

* developing and upgrading laboratories in poor countries to do tuberculosis testing.

* seeking details about two unreported outbreaks of possible XDR-TB over the last 10 years that W.H.O. officials have heard about informally.

The lack of effective drugs brings doctors back to the pre-antibiotic era, when the limited treatment measures included chest surgery. For patients whose tuberculosis was confined to one lung, surgeons could remove a portion of a lung or a whole one, but without assurance of cure.

If the strain keeps spreading it could exceed by "hundreds of times" the outbreak of drug resistant tuberculosis in New York City in the 1990Æs, Dr. Raviglione said. That outbreak was brought under control by adopting strong measures, including observation of infected patients to make sure they took their drugs properly.

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Elisabeth Rosenthal contributed reporting for this article.

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