The public health threat presented by XDR TB was only widely realised after reports of an outbreak at a rural hospital in [b]Tugela Ferry, KwaZulu Natal[/b], in 2006. Daneel Knoetze writing in [s]Groundup[/s] reports that 53 patients at the hospital were diagnosed with the disease. All but one of them died. Government figures now show that from 2004 to 2012 annual multi-drug resistant TB (MDR TB) diagnoses in [b]SA[/b] more than quadrupled to 14,161 cases. Annual XDR TB diagnoses have increased 18 times to the 2012 figure of 1,545. In each case, only about half of these patients were treated for drug-resistant TB.
XDR, like multi-drug resistant (MDR), TB describes strains of the TB bacteria which are resistant to two of the most important conventional TB antibiotics. In addition, XDR TB strains are resistant to two other medicines which can be effective for treating MDR TB.
The [b]World Health Organisation (WHO)[/b] estimated that 480,000 people developed MDR TB globally in 2013, of whom fewer than 100,000 started treatment. But treatment is lengthy, running for up to two years, and the treatment regimens are poorly tested. The medicines can have terrible side effects such as hearing loss, psychosis and kidney problems. By contrast, the six-month regimen for treating drug-susceptible TB, that most patients still get, is thoroughly tested and works well.
It is a gap that [b]SA’s Department of Health[/b] wants to close and in March, Dr Norbert Ndjeka, the department’s director for TB and HIV, outlined a strategy for achieving this by decentralising treatment. This, Ndjeka hopes, will allow more patients to be treated in their communities – because of the state’s limited capacity for hospitalising patients.
The inefficacy of the current drug regimens remains an unaddressed problem, though. Ndjeka’s figures show that success rates, after two years of treatment, are low: approximately 40% for MDR TB and 20% for XDR TB.
Knoetze says the evidence on the effectiveness of drug-resistant TB regimens recommended by the WHO and used in SA and other poor countries is insubstantial. Yet the investment in research is far short of what is needed, warns the [b]US[/b]-based [b]Treatment Action Group (TAG)[/b] in its recent report on TB funding trends between 2005 and 2013. The actual global investment in developing new drugs in 2013 was only $255m, and total worldwide TB research expenditure was less than $700m, far short of what experts say in needed to make serious progress against the disease. TAG has warned of the pharmaceutical industry’s ‘long good-bye’ from the field. The private sector spent 31% less in 2013 than it did in the record year of 2011. Several companies exited TB research entirely, a trend started by [b]Pfizer[/b] in 2012.
‘Drug development in the pharmaceutical industry is driven more by the market than need for new and better treatments,’ says Marcus Low, of the [b]Treatment Action Campaign (TAC)[/b].
‘When it comes to “third world” diseases – be it Ebola or drug resistant TB – there is a lack of investment, because those affected are generally poor. Pharmaceutical companies maximise profits by developing patented drugs. They are accountable to their shareholders, not to patients in need.’
The dearth of investment is coupled with a lack of urgency in fast tracking promising experimental drugs for drug-resistant TB through the stringent clinical trials generally needed for a drug to be approved. Three in particular – linezolid, delamanid and bedaquiline – have shown promise.
Knoetze says treatment activists, like the TAC and TAG, are now lobbying for patients with drug-resistant TB to get access to such drugs before they are approved by regulatory authorities like the [b]Food and Drug Administration[/b] in the [b]US[/b] and the [b]Medicines Control Council[/b] in [b]SA[/b]. This is known as pre-approval access or compassionate use.