EXTENSIVELY DRUG-RESISTANT TUBERCULOSIS: ASSESSING THE RISK

[Snowy Owl]

EXTENSIVELY DRUG-RESISTANT TUBERCULOSIS: ASSESSING THE RISK

Rapid spread of disease alarms experts

http://www.theglobeandmail.com/servl...IDE21/TPStory/

STEPHANIE NOLEN
May 21, 2007

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DURBAN, SOUTH AFRICA<!-- /dateline --> -- The public-health world has been alarmed since the early 1990s about what's called multidrug-resistant (MDR) tuberculosis.
Drug resistance emerges when people are prescribed the wrong drugs or do not complete a course of treatment, which allows for the natural selection of bacteria that are resistant to the drugs.
<!-- /Summary -->MDR is found all over the world, with the fastest growth in cases in China and Russia. It is curable in about half of cases, but patients must take highly toxic drugs for as long as two years to get rid of it. (The other half of people die of the disease within a few years.)
But XDR tuberculosis is something else altogether. The bug is resistant to both the main class of antibiotics used to treat TB, and to at least one of the second class of drugs, which are injectable antibiotics.

This leaves almost no option for treating it. People with HIV have proved utterly defenceless to its spread.

"This is an absolute emergency," Mario Raviglione, director of Stop TB at the World Health Organization, said last month.

"It is the most urgent thing I have seen in my 15 years of working in tuberculosis: a highly resistant strain that is now killing HIV-positive people and is spreading very rapidly.

"Nobody is moving fast enough," Mr. Raviglione added.

XDR has been identified in 35 countries, including one case in Canada and 49 in the United States. It poses a far greater risk than HIV or bird flu because of its transmissibility.

Paul Nunn, an expert on tuberculosis at the WHO, described the possibility of a "nightmare scenario" occurring at next year's International AIDS Conference in Mexico City, at which 20,000 participants are expected, a quarter of them with HIV: "Now imagine someone who doesn't know they have XDR gets on a plane, gets off in Mexico City, 10,000 feet up where everybody is breathing hard ..."

In the past few months, XDR has been identified in every one of South Africa's provinces, in rural villages and in city centres, and TB experts say there is no question that it is also spreading across other countries in southern Africa. However, those countries do not have the infrastructure to diagnose it, and so deaths from XDR are going unrecorded.

Just as AIDS treatment is finally beginning to reach into all corners of South Africa and its neighbours, there is a very real possibility that XDR could spread quickly and cause a massive wave of deaths among people with HIV, by far the most vulnerable group.

New twists on an old illness
Multidrug-resistant tuberculosis is found all over the world, with the fastest growth in cases in China and Russia, and the more serious extensively drug-resistant tuberculosis has been identified in 35 countries, including one case in Canada and 49 in the United States.


Prevalance of MDR tuberculosis among new cases

<TABLE><TBODY><TR><TD>less than 0.9%</TD><TD>1.0% - 2.9%</TD><TD>3.0% -6.4%</TD><TD>more than 6.5%</TD></TR><TR><TD>Mexico</TD><TD>Canada</TD><TD>United States </TD><TD>Equador </TD></TR><TR><TD>Spain</TD><TD>Brazil</TD><TD>Peru</TD><TD>Latvia</TD></TR><TR><TD>Russia</TD><TD>Chile</TD><TD>Argentina </TD><TD></TD></TR><TR><TD>Georgia </TD><TD>Portugal</TD><TD>South Africa </TD><TD></TD></TR><TR><TD>Bangladesh</TD><TD>Germany</TD><TD>Czech Republic</TD><TD></TD></TR><TR><TD></TD><TD>United Kingdom</TD><TD>South Korea</TD><TD></TD></TR><TR><TD></TD><TD>Thailand</TD><TD></TD><TD></TD></TR></TBODY></TABLE>
SOURCE: WORLD HEALTH ORGANIZATION

[Gert van der Hoek]

Re: EXTENSIVELY DRUG-RESISTANT TUBERCULOSIS: ASSESSING THE RISK

World health agency warns of surge in drug-resistant TB

About 420,000 of the estimated 8.8 million new cases of tuberculosis in the world are now resistant to many standard anti-tuberculosis drugs.

Tuberculosis may reach the point where most new cases in some countries are resistant to many drugs unless far greater efforts are made now to stop the spread of the infection, World Health Organization officials said on 5 June.

That chilling forecast is based in part on the organization's analyses showing that on average, a patient infected with drug-resistant tuberculosis in 2004 is resistant to more drugs than a similar patient with that diagnosis in 1994, Dr Paul P Nunn, a TB expert for the organization, said at a news conference.

The case of Andrew Speaker, the Atlanta man with extremely drug-resistant tuberculosis who took commercial flights for his wedding in Greece and honeymoon in Europe and set off an international health scare, has focused attention on the disease, and prompted the news conference.

Health officials say that Speaker's was not an isolated case because the extremely resistant form has been reported in 37 countries. With the growth of international travel, health officials say that TB anywhere is TB everywhere. About 420,000, or 5%, of the estimated 8.8 million new cases of tuberculosis in the world are now resistant to many standard anti-tuberculosis drugs, Dr. Mario C. Raviglione, who directs the WHO's tuberculosis department, said in an interview.

About 30,000 of the 420,000 cases are extremely drug-resistant, meaning they are resistant to first-line and a number of second-line drugs.

Raviglione said the organization had begun to undertake statistical modeling studies to estimate how prevalent drug-resistant tuberculosis might become. Outcomes from such studies depend on a number of variables and none have been published.

"It is possible that in some settings drug-resistant tuberculosis could completely replace standard tuberculosis," Raviglione said. That possibility is greatest in settings where poor public health services and laboratory facilities mean that no one knows the number and proportion of tuberculosis cases that are susceptible and resistant to drugs. In such areas, many people do not know they have tuberculosis.

An area of great concern is Africa, where AIDS patients often develop tuberculosis. Other areas are China, Eastern Europe and India. Coughing, sneezing, singing and other activity spread the tuberculosis bacteria in the air. Anyone can become infected, but prolonged exposure is usually required.

http://www.livemint.com/2007/06/06131329/World-health-agency-warns-of-s.html