How do we fight an airborne, infectious disease that we haven’t been able to effectively track?
We have a fairly solid sense of how much drug-susceptible tuberculosis exists today. More than 1.4 million people die, and 9 million new people contract TB each year around the globe.
But drug-resistant TB has slipped under the surveillance radar for decades, with a price. The lack of data is making it difficult for advocates, researchers, and storytellers to explain to the public just how threatening and deadly the current drug-resistant TB epidemic is right now.
Take India, which has the second-highest TB burden in the world. As of 2011, the World Health Organization believes around 73,000 people in India have multidrug-resistant TB right now; the Wall Street Journal reports 100,000. But tallies from India are coming from ‘limited sub-national areas.’ There are no nation-wide surveys of drug resistant TB cases in the country as of yet and India reported no data at all for how many people have been tested for drug-resistant TB.
Even worse (and more confusing)? The WHO estimates that just 6% of TB patients who actually had drug-resistant TB in 2011 were diagnosed as such. If this is true, then given India has 3.1 million TB cases, that means there’s around 2.9 million people in India who have drug-resistant TB and don’t even know it.
Dr. Ramanan Laxminarayan of the Public Health Foundation of India and the University of Princeton has been studying drug resistance for more than a decade. When I cocked an eyebrow at him about the high rates of DR-TB cases in India, he cocked an eyebrow right back.
“I mean, fine. You point fingers at India, but the fact is everyone missed this,” he said, ‘this’ meaning the capability and growth of drug-resistant TB. Dr. Laximinarayan has been researching drug-resistance for years; he’s not unused to explaining its potential. “But the bugs are smart, I mean, you hit them with one thing and they’re going to figure out how to become resistant.”
TB patients wait for their treatment at a DOTS Centre near New Delhi, India. Several
of these patients have drug-resistant TB.
So far, TB has done just that.
Drug-resistant TB is just what is sounds like: strains of Mycobacterium tuberculosis that do not respond to treatment.
Multidrug-resistant TB (MDR-TB) is unaffected by at least the two most powerful treatments (isoniazid and rifampicin).
Extensively drug-resistant TB (XDR-TB) does not respond to even more TB medications.
The WHO says we don’t have enough data to make conclusions about MDR-TB and XDR-TB trends.
But the three dozen infectious disease scientists, policy makers, advocates and researchers I spoke with about DR-TB agreed: new resistant strains of TB are posing a serious and growing danger now more than ever before.
And for the most part, the world outside of the TB-focused institutions — meaning most of the world — have not paid mind.
Why aren’t we talking about drug-resistant TB?
It could be chalked up as a research problem: since the data is so sparse, posing DR-TB as a global threat is a tough sell. A number of obstacles — poor lab infrastructure, patients hiding their disease to avoid societal stigma, lack of accurate diagnoses before a patient passes away, to name a few — make sleuthing out the actual number of cases we have in the world pretty difficult. Any estimates we do have on TB cases are likely far below the truth.
It’s a social problem: TB exists and thrives mostly among the poor, marginalized and malnourished; these communities have less access to health care, can go untested or undiagnosed, and can be very hard to survey. Patients don’t always want to tell their family, friends, or neighbors that they have TB, fearing the social rejection and fear surrounding the disease.
Sputum samples in a New Delhi lab await analysis.
It’s a scientific problem: drug-resistant TB is hard to test. Only recently has the sector developed a way to find out if a strain of TB will turn out to be resistant to the first-line drug treatments. So the most common way to treat drug-resistant TB right now is to put someone on a drug, then wait at least six months, as they take handfulls of pills per week, to see if they respond to them. As you’ll see from a young South African girl named Phumeza in the film below, this way of treatment can devastate — or even ruin — a life.
We’ve made some progress of late on surveillance: India recently labeled TB a ‘notifiable disease’, meaning doctors and patients and family members of patients are required to report cases of TB in their communities to the government if they’re aware of them. A recent rapid diagnostics machine called the GeneXpert has helped identify TB cases (and even some forms of drug-resistant TB cases) within as little as an hour’s time. These are a start. But across the world, new drug-resistant strains of TB continue to pop up everywhere, and the TB sector is well aware that their data is not telling the whole story.
An updated map of extensively drug-resistant TB (XDR-TB) incidence will show you a cluster of countries with XDR-TB; at first glance, you may think, “Ok, it’s not so bad, right? It’s not like XDR-TB is in every country in the world…” But experts told me that the map is more an indicator of our testing progress than it is of actual XDR cases. XDR isn’t necessarily limited to these countries; these are the 69 countries who have been able to submit data identifying XDR-TB:
This map is constantly changing to include more countries testing improves. The lack of reliable or definitive data makes it hard for global health professionals to gauge the gravity of the TB epidemic. But it also makes reporting on TB hard. How many caveats can you include in citing disease rate data before the whole thing seems irrelevant or not worth reporting until we really know?
TB has afflicted humans for centuries. It’s runner-up to HIV in the world’s most deadly infectious diseases. And yet, TB remains a relative blip on the global health agenda radar. Take the recent 66th World Health Assembly, for example, which brought together around 2,000 delegates from each of the WHO Member States for ‘intense discussions’ on global health priorities. The week-long gathering resulted in ‘key outputs,’ or what the WHO states are the most important diseases and health concerns on the globe. A glance over the agenda will show coronavirus, malaria, polio and other diseases called out specifically for discussion. Tuberculosis rests, as it tends to, snugly in the long list of other Millenium Development Goals, and with a cheery update: that TB cases and mortality rates across the world are declining, that treatment coverage is doing better than expected. Nothing about drug-resistant TB. Nothing about improving or reducing the incredibly long timeline of treatment (which has contributed to, if not caused, drug-resistance in the first place). Nothing about the need for new data or surveillance of DR-TB, nothing about improving diagnostics, and a blink of a mention of TB vaccines.
“Yes, the number of people with tuberculosis is going down slightly,” Aaron Oxley, Executive Director of a TB advocacy organization called RESULTS in the UK, told me in February. “But the number of people who have drug-resistant TB is going up, and nobody’s talking about it.”
Can the world afford to wait for the numbers that prove drug-resistance is a major global threat? From Anthony Fauci at the US National Institutes of Health to Khasim Sayyad, a local health worker in New Delhi, the experts I spoke with don’t think so.
Right now, we know at least 3-4% of TB cases in the world are drug-resistant. That feels like a minuscule amount, and if DR-TB stays there, it might be. But tuberculosis is an airborne disease. Beyond the current strains of DR-TB floating around right now, new and even more resistant strains are already popping up (XDR-TB). TB has already started evolving; it is outpacing the drugs we have to fight it.
“It would be extremely foolish for us to ignore MDR-TB at this point,” said Dr. Laxminarayan. “First the resistant strains are weaker than the non-resistant strains and then over time they pick up these other mutations which enables them to be just as fit as what they were with less resistance…”
He paused. “We would have an absolutely nightmare on our hands.”
The world is full of diseases that threaten us; it’s no surprise that we prioritize the ones that statistically affect the most people. But when it comes to an airborne, mutating superbug, can we afford to wait for the disease to affect many more?
Learn about drug-resistant TB in Chapter 2 of a four-part series on tuberculosis, supported by nonprofit Aeras, called Exposed:
See all the Exposed films at aeras.org/exposed.