A strain of tuberculosis that is resistant to all existing TB drugs has emerged in Mumbai, India.
"We currently have 12 confirmed cases, of which three are dead," says Zarir Udwadia of the Hinduja National Hospital and Medical Research Centre in Mumbai, and head of the team whose diagnoses of four cases has just been published.
The emergence of the disease in such a densely populated city is a major concern as it could spread so easily. "We know one patient transmitted it to her daughter," Udwadia told New Scientist. "It's estimated that on average, a tuberculosis patient infects 10 to 20 contacts in a year, and there's no reason to suspect that this strain is any less transmissible," he warns.
For patients, the outlook is grim. "Short of quarantining them in hospitals with isolation facilities till they become non-infectious – which is not practical or possible – there is nothing else one can do to prevent transmission," says Udwadia.
The worry is that if it continues spreading, TB will become incurable again and patients will have to rely on their immune system, rather than medical intervention, to overcome the illness – a scenario last seen a century ago.
The World Health Organization is urgently organising a meeting to review the evidence and decide what steps to take next. "This is a problem that was predicted," says Paul Nunn, coordinator of the STOP TB department of the WHO in Geneva. "It's a wake-up call for countries to accelerate provision of proper care, particularly for multidrug-resistant patients," says Nunn.
"It's very worrying, but kind of inevitable, given the gradual emergence of resistance," says Ruth McNerney, a TB researcher at the London School of Hygiene and Tropical Medicine. "It's like watching a slow-motion horror movie unfold."
Multidrug-resistant (MDR) TB, which is resistant to the mainline treatments isoniazid and rifampin, emerged in the early 1990s. In 2006, extensively drug-resistant (XDR) strains emerged, defying all the expensive second-line treatments too.
Now, the focus may switch to totally drug-resistant (TDR) tuberculosis. The first two cases of TDR were reported in Italy in 2007. Then, 15 patients with TDR were reported in Iran in 2009.
The Indian report is the first since then. Udwadia blames the emergence of totally untreatable TB on poor management of the MDR strain. "Years of mismanagement of MDR-TB at government and private care levels resulted in amplification of the level of resistance till we finally ended up with this untreatable strain," he says.
He adds that while India has made huge strides in controlling conventional TB through its national programme, it has failed to provide the same level of support and treatment for patients with MDR-TB – not least because the drugs can cost between $2000 and $12,000 per patient. Treating conventional TB costs just $20 per patient.
Patients with MDR-TB – of which there were 110,000 in India in 2006 – must turn to private practitioners for help. They seldom receive proper treatment, though. Udwadia surveyed 106 private practitioners in a Mumbai suburb and found that only five of them would prescribe the correct prescription if approached by a MDR-TB patient.
Nunn agrees that this is a major problem in many countries, calling on governments to accelerate and boost programmes to diagnose and treat MDR-TB, despite the cost.
He thinks it is possible that drugs such as clofazimine and thioacetazone might yet be able to treat the new form of TB, but they have serious side effects. Thioacetazone strips the skin off patients with HIV, for instance. So the best response is for countries to step up surveillance and treatment for MDR-TB.
"We must wake up the politicians," says McNerney. "Do we wait until it starts to come to the UK and the US on airplanes, or do we act now?"
Journal reference: Clinical Infectious Diseases, DOI: 10.1093/cid/cir889