Working towards solutions for drug-resistant TB

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​Tuberculosis (TB) is the most common cause of death in South Africa and a national public health emergency.

Professor Keertan Dheda, UCT. (Michael Hammond)

There are four main antibiotics for treating TB; but, resistance to these has built up over the years. 

Multi-drug-resistant TB (MDR-TB) has resistance to the two main antibiotics and extensively drug-resistant TB (XDR-TB) has resistance to four of the key anti-TB antibiotics. Totally drug-resistant TB (TDR-TB) is one step further, a super resistant form of the disease. 

“These TB strains lead to high death rates, are almost impossible to treat, spread rapidly and — despite forming a small proportion of the caseload — its management consumes more than 50% of the national TB programme budget,” says Professor Keertan Dheda, professor of respiratory medicine, director of the Lung Infection and Immunity Unit and head of pulmonology at the University of Cape Town. 

The work of Dheda and his collaborators is improving the understanding of the diagnosis, treatment, transmission and control of TB. It cuts across South Africa, Africa and the world. 

A key finding saw Dheda and his team identify drug-susceptibility patterns in patients with highly drug-resistant TB. It showed precisely which drugs are still useful and means treatment can be fine-tuned.

Treatment failure has also been defined. “In general with incurable TB cases, only about 20% respond to treatment and 10-12% have a successful outcome. The research showed a time point beyond which treatment is futile,” says Dheda. This is now used in clinical practice and provides evidence-based information for national resource allocation.

His research has shown that advanced diagnostic technologies don’t have to be restricted to central laboratories. Conducted by minimally-trained healthcare workers, the tests can be deployed, when appropriate, in peripheral health outposts and TB hotspots such as prisons. It reduces result time from two days to two hours.

Other research validates the use of intensive case finding where the healthcare system goes out into the community to find TB cases. Dheda says that currently more than half of drug-resistant TB is undiagnosed. 

The problem of drug-resistant TB in healthcare workers, already in short supply in the country, has been highlighted. For the first time we now know that highly drug-resistant TB is six times higher in healthcare workers than the general population, suggesting that it is contracted at work. This research output played a seminal role in prioritising the national rollout of infection control measures. 

In fact, a large body of his research has impacted on both national and international policy formulated by the WHO and the South African National TB Programme.

Dheda has been widely published, including several times in the prestigious The Lancet. It was through that channel, in January 2014, that he described the scale of the incurable TB problem in South Africa. It is the first time this had been done.

He holds three patents. The Smart Mask monitors the spread of incurable TB and can pinpoint location via GPS, the number of people around the subject using CO2 levels and whether the user is wearing the mask through temperature-based sensitivity. There is also cough frequency monitoring technology. Anonymous data is sent to researchers by SMS.

The other two patents focus on diagnostic testing and alternatives to using sputum (which is often unobtainable in HIV-infected persons). 

Dheda says that the current treatment for MDR-TB has a success rate of less than 50%. A new study funded by the South Africa Medical Research Council will test several new drugs. These need a much shorter treatment time, are far less toxic and there are no injections. 

“This is the first time that this novel regimen for drug-resistant TB is being tried internationally,” says Dheda. If successful, it will change how drug-resistant TB is managed globally.

This supplement has been paid for by the Mail & Guardian’s advertisers. Contents and photographs were supplied and approved by the NSTF.

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