South African Press Association - November 7, 2007
Ben Maclennan

Usdin, a biologist working for MSF's campaign for access to essential medicines, was speaking in Cape Town, South Africa today where she was attending a symposium organised by the campaign on TB diagnostics.

"The fact of the matter is, it's estimated that half the world's population is infected with TB, so two million people a year are dying of the disease, nine million are getting sick a year," she said in an interview.

"It's on the scale of a global health emergency.

"These are numbers that we have to move from the kind of written-on-paper number, to...the fact that we need to be moving very quickly to try and address the problem."

She said that in the developed North, TB was taken extremely seriously.

If a person in the United States had a skin test which showed he or she might have been exposed to TB, enormous resources were mobilised to diagnose and give preventive treatment.

By contrast some 80 percent of South Africans showed tubercular positive in skin testing, which gave an indication of the difference in the magnitude of the problem in the developed and developing worlds.

She said most TB cases were in resource-poor settings, while the bulk of resources available for diagnosing and caring for TB cases was in resource-rich settings.

"Here in South Africa there's an enormous prevalence of TB, compounded by co-infection with HIV. The majority of patients are not getting access to the most simple, basic kinds of testing."

According to MSF, TB is the leading cause of death among people who are HIV positive. Without treatment, it says, about 90 percent of them will die within months of contracting the disease.

"The tests are inadequate in that they're slow - patients have to wait a long time to get their results - they're not sensitive enough, and they're often not adapted to where the patients are," Usdin said.

Some tests were feasible only in a laboratory setting and were either very expensive or required special equipment, operated by trained technicians in a controlled environment.

"For an organisation like MSF, whose patients are often out in the field, for us to get those kinds of diagnostic capabilities to where our patients are, it's an enormous challenge, and there are no really well-performing tools that can do that job," Usdin said.

TB was never easy to diagnose, regardless of who the patient was, or where the test was being carried out.

Most settings were able to do microscopy - a relatively simple test, examining a spit sample from a patient.

The problem was that though the test had been around for 100 years, it did not work very well.

"At best, in the very very best lab, with the most experienced hands, the best...equipment, you can detect 30, or 40, or maybe 50 percent of the patients who actually have TB," she said.

Culturing a sample was a more sensitive test, but there was a shortage of human resources to do all the testing needed.

"Then the culture techniques that exist today, you can only do in a very well-supported lab. Well-supported means you have air conditioning, running water and enough trained technicians, you have the money to buy the equipment that you need.

"All of that means, if you have a patient in front of you and you're worried they might have TB and you need to do something for that patient, your options are significantly limited already about what you can do for that person.

"So we need better tests. We need tests that can be performed more quickly.

"We also need tests that can handle the volume of samples, and that can handle people that are HIV positive, where the chances of diagnosing TB are reduced but the probability of having TB is enormously increased."

The "tragic thing" about TB was that a person could contract it even if they were doing fairly well on the HIV side of the scale, on antiretrovirals with a stable CD4 count.

Unlike HIV, where activists were pushing for everyone to get access to the same diagnostics and treatment whether they were in developed or developing countries, TB was poorly diagnosed everywhere.

Part of the reason was that in the North, TB was such a rare disease that there had been no interest in developing new tools.

"TB is fundamentally a disease of poverty. So if you're poor, you're more likely to have TB, you're less likely to have access to early diagnosis and treatment.

"For that reason I think there's been a [focus] in world attention on other issues. Nobody's really looking as hard as they should for good diagnostics.

"The perfect test does not exist yet."

She said some work was being done, and ogranisations were trying to stimulate research and development, but there were difficulties with the kinds of tests being developed.

"What we really need are tests that are able to be used where most of the patients are."

And although TB had been around for so long, little was known about its basic biology.

"So we're sort of playing catch-up to even get the basic knowledge that we need to develop a new test. It's an enormously complex and difficult problem, because the organism is so clever at doing what it does, making us sick.

"But the fact of the matter is that we can do better. And it's our moral responsibility to be doing the best we can, now.

"And the longer we wait to do right, the more the problem is compounded, the worse it gets - there's more MDR [multi-drug-resistant TB], there's more XDR [extreme-drug-resistant TB], more patients are getting sick."

She said: "The more patients that fly around the world coughing in aeroplanes, the more people in the North and the West are concerned about catching TB themselves, I think the more people will start to talk about what a global health emergency it is."

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