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A bazooka in the fight against TB

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GeneXpert MTB/RIF test provides hope for clinicians and laboratory workers trying to manage TB.

The battle against tuberculosis (TB) has a bazooka in its armaments with the GeneXpert MTB/RIF test that provides hope for clinicians and laboratory workers trying to manage the disease.

GeneXpert is a simple cartridge-based diagnostic test that automates sample processing on sputum, providing real-time results.

Identified as the first-line test to diagnose active TB throughout South Africa, the test provides a diagnosis in less than two hours, both of TB itself and of resistance to the drug rifampicin, a surrogate marker of multi-drug resistance and one of the first-line drugs in TB treatment.

This means that people can be tested, diagnosed and started on multi-drug resistant treatment on the same day — a far cry from the up to three month waiting period for smear-negative TB suspects prior to the introduction of GeneXpert.

Rifampicin-resistance is a good indicator of multi-drug resistant TB (MDR-TB), an additional complication in what has long been one of the world's worst killer diseases. MDR-TB is a severe form of TB that is difficult to diagnose. Being multi-drug resistant, it is challenging and costly to treat. TB is known to be a disease of poverty, linked to several socio-economic factors. TB prevalence in people with HIV is high and HIV negative individuals have a 10% life-time risk of developing TB. HIV positive sufferers have a 10% yearly risk for developing TB.

Out of South Africa's population of 50-million people, 500 000 contract TB each year.

In 2011, 5 643 people were treated for MDR-TB. South Africa has the third highest TB burden in the world (after India and China) and the fifth highest drug-resistant TB burden.

The national department of health's director for the drug-resistant TB division of the national TB programme, Dr Norbert Ndjeka, said the main benefit of GeneXpert is early diagnosis.

"The earlier we can diagnose TB sufferers, the sooner they can be put on effective treatment. This is the best way to cut TB transmission. Late diagnosis affords TB sufferers an opportunity to infect more people while waiting to be diagnosed and treated.

"Accurate diagnosis and effective treatment renders TB sufferers non-infectious, which is safe for communities," said Ndjeka.

The head of molecular medicine and haematology at Wits University and the national priority programmes of the National Health Laboratory Service (NHLS), Professor Wendy Stevens said South Africa has managed a record rollout of the GeneXpert instruments since their introduction in March 2011, with 143 instruments covering 100 sites across the country.

More than 800 000 tests were performed over the last 18 months. "The rollout involved an initial pilot phase, with one high-burden district in every province identified and tested. "The success of the project has been overwhelming. Some 125 more devices will be placed over the next six to nine months, boosting the number of instruments implemented to about 265. Their further placement in or close to clinics will ensure our treatment interventions follow through."

Stevens said one of the challenges facing the NHLS and the national department of health going forward was the training of thousands of laboratorians and clinicians on how to conduct and interpret results from the GeneXpert.

"The success of broad-range awareness campaigns on TB have resulted an increasing number of people coming forward for testing, which places pressure on facilities and testing sites. "South Africa's challenge is sheer volume. The challenge facing the rest of Africa will be financial constraints around equipment costs.

"Sourcing donors is one thing, but achieving long-term sustainability is a far greater challenge," said Stevens.

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