Drug-resistant Tuberculosis

Very much an issue, and it’s spreading like wildfire

New strains of tuberculosis (TB) threaten efforts to eradicate one of the world’s deadliest diseases. An alarming study published in the March edition of the U.S. Centers for Disease Control and Prevention’s Emerging Infectious Diseases journal reveals the discovery of the first cases of totally drug-resistant TB in South Africa. These findings come on the heels of the discovery of virtually untreatable strains of TB in the hospital wards of Mumbai, India last year.

TB, a bacterial lung disease, infected an estimated 8.7 million people in 2011, according to the most recent statistics from the World Health Organization (WHO). While inactive in the majority of those infected, the active form is transmitted through air. The disease is a leading infectious killer worldwide. Second only to HIV/AIDS, it kills one person every ten seconds. In those afflicted, it leads to severe weight loss, chronic coughing – often of blood-stained mucus – and destruction of lung tissues. Dr. Madhukar Pai, a leading McGill tuberculosis expert, explained that the disease is not only physically debilitating, but also accompanied by social stigma and a heavy economic burden.

Multi-drug-resistant TB (MDR-TB) encompasses strains of the bacteria that do not respond to two critical drugs used to treat TB, isoniazid and rifampicin. When an individual is infected with the drug-resistant bacteria, physicians have to resort to ‘second-line’ drugs for treatment, which, according to Pai, have many side effects, are more expensive, and are not readily available.

“The regular drug-sensitive TB requires a standard six month treatment, [and] it’s not inexpensive, like three days of antibiotics,” he explained. “[For MDR-TB] that treatment lasts two years…even if you give all of this stuff for two years, about 50 per cent of patients are dead.”

In the past five years, a subset of patients has begun developing extensively drug-resistant tuberculosis (XDR-TB), which is resistant to even more drugs and has worse survival rates. Although the WHO has not yet formally adopted the term totally drug-resistant TB (TDR-TB), the strains identified in India and South Africa are believed by researchers to be unresponsive to all known drugs.

While the contexts of India and South Africa are very different, Pai says drug resistance in TB has similar “underlying drivers in both countries.” In India, the mismanagement of patients, which pushes them from physician to physician, has been identified as an important culprit in exacerbating TB. Poor diagnostics and fake drugs, which make up 10 per cent of the total TB drug supply in India, also leave patients receiving ineffective treatment.

The crisis is further complicated in South Africa, where nearly one out of every five adults lives with HIV. The presence of “extensively drug-resistant TB plus HIV” Pai says, “is a complete disaster.”

In recent years, a combination of efforts, including vaccination campaigns and national control strategies, have been implemented to fight TB by the South African government. However, the fight remains at a standstill as the casualties rise. The TB vaccine of choice BCG (Bacillus Calmette–Guérin), developed ninety years ago, is only partially effective.  The rise of drug-resistant strains has prompted greater efforts to develop improved vaccines against the disease in order to protect people before they’re infected, but these efforts have led to disappointment. In February, MVA85A, which was touted at the first new TB vaccine in a century, failed clinical trials.

Meanwhile, control efforts have given mixed results. Some reports suggest that India’s current strategy to defeat TB may actually be promoting more deadly drug-resistant strains. In an interview with the Wall Street Journal, Dr. Zarir Udwadia, whose research team discovered totally drug-resistant TB in India, criticized the country’s strategy as “a futile exercise [that will] serve to amplify resistance.”

One of these strategies includes giving the same standard regimen of drugs to anyone suspected of having TB, without checking for resistance, which would entail additional costs. For some patients, these regiments do not work and only heighten the presence of drug-resistant strains. Similarly, in Eastern European countries, poor management of TB has only aggravated the problem. Other strategies have included quarantining. Notably, in South Africa, when extensively drug-resistant tuberculosis broke out, many patients were involuntarily detained in prison-like hospitals.

“It doesn’t work. They broke out,” Pai said. “Keep on doing the wrong thing and you end up with drug-resistant bacteria that don’t respond to any interventions.”

The broadest effort to combat TB, the Stop TB Partnership, consists of 1,000 international governmental and non-governmental organizations. The project aims to provide treatment for fifty million people and prevent 14 million deaths by 2015.  However, the economic crisis has led some countries to reduce or stop contributing to TB prevention programmes.

On March 21, McGill University launched its International TB Centre in an event attended by experts from across Canada. Dr. Anne Fanning, researcher at the University of Alberta and the Chair of Stop TB Canada, described global efforts against TB, local efforts against TB particularly in Inuit communities, and scientific research as three areas that need serious attention.

“[All of this] needs the support of the government of Canada,” she emphasized.

Pai similarly believes that all countries need to take TB more seriously. He warned that the chronic underfunding of these programs across the world might only lead to compounded costs for everyone later.

“In today’s day and age there is no sense in thinking of global health as a problem that doesn’t bother us or affect us.” He said, “TB anywhere is TB everywhere.”