06 August 2008

Quick tests = fewer TB deaths

A rapid diagnostic test for multi drug-resistant tuberculosis (MDR-TB) is being rolled out. But what does that really mean for patients, the public and the Department of Health?

A rapid diagnostic test for multi drug-resistant (MDR) tuberculosis is being rolled out by the Department of Health (DoH), the Minister of Health, Dr Manto Tshabalala-Msimang, announced earlier this month in Durban.

But what does that really mean for patients, the public and the DoH?

We know that tuberculosis is one of South Africa's biggest public health problems, with over half a million cases expected this year. We also know that the high prevalence of HIV is fuelling the spread of TB, as HIV-infection increases the risk of acquiring active TB tenfold.

"More than 60% of TB patients in South Africa are co-infected with HIV, presenting unique challenges for patient management, disease control efforts and infection control," according to a joint statement from the Medical Research Council (MRC), Foundation for Innovative New Diagnostics (FIND), the National Health Laboratory Services (NHLS) and the DoH.

To complicate this already sticky situation, the tuberculosis bacteria has developed strains that are resistant to first-line medication (MDR-TB), and second-line medication (extensively drug-resistant [XDR] TB).

"Spread of MDR-TB and XDR-TB to vulnerable populations such as HIV co-infected individuals can have devastating consequences – aside from the much reduced possibility of cure, HIV infected patients who contract MDR-TB or XDR-TB may develop complications more easily and as a result the death rate is very high."

Advantage of speeding up diagnosis
Until now, the diagnosis of MDR-TB could involve a laboratory time lag exceeding two months, and a total lag from time of testing of four months or more.

"Using existing technology, diagnosis of drug-resistant TB can take up to four months, during which time a patient remains highly infectious and often in the community, thus also spreading this form of TB to others," said Tshabalala-Msimang at the launch of the new test.

With the new rapid diagnostic test, results will be processed within seven days.

"This has revolutionised the diagnosis and therefore the management of drug-resistant TB, with benefits to individual patients as well as public health generally," said Tshabalala-Msimang.

Indeed this new technology's benefits stretch through all spheres affected by the disease. For the individual a rapid diagnosis results in earlier treatment, increasing their chance of cure and survival.

On the community level, it could help control infection of MDR-TB. Regular TB-medication is ineffective against MDR-TB infection, and patients remain infectious until they receive the appropriate medication. Bringing the diagnosis date forward by several months can save hundreds, and even thousands, of people who might have been exposed to the germ during that time, from this risk.

Often MDR-TB patients are removed from communities and placed in TB hospitals, once again removing the risk of infection from the community.

For the DoH the benefits of this new test are twofold. Rapid diagnosis of MDR-TB could greatly improve the efficacy of their TB-control strategy by reducing infection. Consequently the DoH will save millions on costs, as the treatment for MDR-TB costs R25 000 for drugs alone. "Including hospitalisation and other costs, treatment of MDR-TB could cost the DoH up to R100 000 per patient," said Dr Lindiwe Mvusi the DoH's TB program manager.

"Furthermore, utilisation of this test in the field is envisioned to reduce overall laboratory costs to the National Tuberculosis Control Program," said Dr Gerrit Coetzee, head of the National TB Reference Laboratory of the NHLS.

Making history
For this new diagnostic test to be approved, a demonstration study under field conditions involving 20 000 TB patients at risk of MDR-TB was conducted in four provinces in South Africa.

Outcomes of this study showed that the test has the potential to "revolutionise the control of MDR-TB", and as a result of this study, its use in TB control programmes in developing countries was endorsed by the World Health Organization last month.

Scientists from MRC, FIND and NHLS have combined efforts with national and provincial departments of health to demonstrate the new test, called the 'line probe assays'.

When will it be fully functional?
According to Mvusi the rapid diagnostic test is already fully functional in the four provinces where the study took place and a work plan in being finalised for the implementation of the new test method in five more provinces.

Said Tshabalala-Msimang: "Officials from the DoH, together with colleagues from the NHLS and the MRC are now working on the diagnostic algorithms (problem-solving procedure), and the implementation plan to ensure that all provinces have access to this test and that training is conducted on the revised TB diagnostic algorithms."

Specialised laboratory facilities and specially trained personnel are required to perform the test. "We need to upgrade the existing infrastructure, and personnel have to undergo specialised training. But all things considered, we envision this new procedure to be fully operational in all provinces by the beginning of next year," Mvusi concluded.

- (Wilma Stassen, Health24, July 2008)

Read more:
Breakthrough TB test in SA
TB: SA gaining ground, says Manto


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