24 March 2011

TB diagnosis breakthrough

Health Minister Aaron Motsoaledi today announced that the revolutionary GeneXpert MTB/RIF machine will be rolled out across the country.


Health Minister Aaron Motsoaledi today announced at the Prince Nshiyeni Memorial Hospital in Umlazi, KZN that the GeneXpert MTB/RIF machine: a revolutionary TB diagnosis machine that dramatically cuts lag time and test complexity, will be rolled out across the country. 

The machine could be the difference between life and death for millions of people.

The GeneXpert MTB/RIF is about the size of a coffeemaker and makes accurate TB diagnoses within just two hours. Simultaneously, it also tests for resistance to rifampicin, one of the major drugs used in the treatment of TB.

Why is this important?

Consider this: one in every three people in the world is infected with TB. South Africa ranked third in the world in terms of total numbers of incidence cases of TB in 2008, with a particularly high concentration in the Western Cape.

TB is more common among the poor, or people living in overcrowded areas, but it is not restricted to that demographic. If you share taxis, trains, or any enclosed space with someone who is infected, chances are you have been exposed to, or infected by it.

Being infected doesn't mean you are sick, coughing or wasting away. The TB bacteria can be dormant in your body for years, waiting for the day your immune systems is weakened when it takes hold, and doesn't let go.

 "Anyone exposed to TB runs the risk of converting to active TB in time, especially if they are HIV+ or immune-compromised for some reason (e.g. severe viral illness, occupational disease, cancer, chronic illness)," says Dr David Clark Deputy CEO of the Aurum Institute.

When that day comes, the GeneXpert MTB/RIF may turn out to be your best friend.

The current method of diagnosis is based on the sputum test where a sample of your sputum (phlegm-like substance coughed up from your gut) is collected. Ideally, it goes throughmicroscopy (looking for the TB bacilli under a microscope, which picks up between 40 and 60% of cases) and is cultured (grown in a special culture media, which takes two to six weeks). Due to limited resources this is not always possible, leading to misdiagnoses. "In the era of HIVespecially, not all samples that are TB infected are found to be positive under the microscope," says Clark.

The wait for culture results is problematic. "It is a long wait, during which time the patient continues to spread TB in the community," says Clark. The delay in results also means the patient is kept off treatment for an extended period, resulting in them becoming more sick.

"Certainly the earlier diagnosis is made the sooner people can be put onto curative treatment. But the benefits are more extensive than that," he explains. “Early treatment leads to less infection from people moving about in the community with active disease. Early successful treatment means less likelihood of the development of resistant TB (MDR-TB and XDR-TB)."

So in the two weeks you are waiting for a diagnosis, you are exposing your family, friends, colleagues and everyone else you get in contact with, to the TB bacteria. Research estimates that each person infected with TB infects 15 more people with this disease.

If the GeneXpert MTB/RIF were implemented, you can walk into a clinic, and know your TB status the same day. Start the appropriate treatment straight away, and you stop being infectious immediately.

Understanding the stats

South Africa, ranked by the World Health Organisation as one of the countries worst affected by TB in the world, would greatly benefit from the GeneXpert MTB/RIF.

"Since TB is at epidemic levels in our country, everyone stands to benefit from better diagnostics for TB," says Clark.

"There are economic benefits to earlier diagnosis and treatment, fewer people are off work, or unable to work or dead, leaving people behind who cannot cope. Early treatment leads to easier out-patient treatment instead of expensive hospital admissions. But most importantly, tackling TB decisively helps people move out of poverty into meaningful life."

A rapid diagnostic tool would also lighten the load of laboratory staff, freeing up resources previously spent on diagnostic, to actually work towards treating the disease.

Unfortunately, the GeneXpert MTB/RIF, being the first real development in TB diagnostics in 100 years, is expensive. It costs over R100,000 and the hardware used in each test costs over R100.

Realising the value of the device, activists are now calling for the price of the machine to be reduced to make it affordable to regions were the epidemic is most serious. The Bill and Melinda Gates Foundation and the WHO have also supported drug companies in making the GeneXpert MTB/RIF available to 116 low and middle-income countries, including South Africa.

Negotiations are underway and we are waiting to hear if and when the GeneXpert MTB/RIF will come to South Africa.

(Wilma Stassen, Health24, March 2011)

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