Expanding screening as a key strategy for tuberculosis elimination

Global health is in my blood. Both of my parents are physicians, and as a student I spent my summers working in refugee camps. There I saw people with life expectancies in the 40s because of infectious diseases. I saw tuberculosis and HIV everywhere I worked.

But the truly life-changing moment came when I was part of a research project in Cape Town looking at the predictors of mortality in a TB hospital. And it wasn’t co-infection with HIV, it wasn’t age, it wasn’t malnutrition – it was none of the things we expected. It was the misdiagnosis of TB.

Very well-meaning doctors without the proper diagnostic resources were sending patients to the hospital believing they had TB, and these patients were dying from whatever their primary disease was. And not only did the person who didn’t receive the right therapy die, but the person who needed that bed and didn’t get it probably died as well. That changed my whole life – it’s when I knew that diagnosis was all there is.

When I was recruited to be the Chief of Occupational Health at the Palo Alto VA, a position I help for 15 years, my condition of hire was that we never do the TB skin test again, and that we’d switch 100% to the QuantiFERON TB test.

People who weren’t born in the U.S. and had a BCG vaccine as a child may well show a false positive with a skin test (1), so why would we do a test that we know doesn't work? People were getting positive TB tests and doing nothing about it because they didn't believe the result – they wouldn’t get latent TB treatment, and they wouldn’t get tested again. So we were doing exactly the opposite of what you need to do if you want to prevent TB.

The consequence of the wrong diagnoses

With the tuberculin skin test TST, latent tuberculosis was being overdiagnosed by more than 50%, meaning it was almost a coin toss as to whether a result was accurate. And that wrong diagnosis puts a huge burden on people – telling someone they have a disease that could kill them or their child one day. It’s terrifying.

So now when we say “I have a test that can tell whether or not it’s your vaccine that's giving you the positive test, and I can give you the answer in two days and a treatment that's just 12 days of antibiotics” – that’s a game changer.

When we have educated healthcare professionals and the resources to do the right diagnostic and follow that up immediately with the new short course therapies, nobody else even needs to know. So people can now just take care of themselves, be proud of themselves, and feel stronger and safer knowing this isn't something they have to keep an eye on for the next 20 years.

The old treatments for latent tuberculosis of nine to 12 months of daily isoniazid (INH) were sometimes dangerous, causing liver damage or death, but we're in a whole new era with an accurate diagnostic and therapy as short as 12 once-weekly doses that's effective, safe and has high compliance.

It’s also getting less and less expensive and costs a trivial amount when compared to treating the active disease and all the infections that come with that.

In the United States, public health has done an incredible job in bringing down rates of active TB, but we don't really know the rates of latent TB because we still rely so much on skin testing. It's a huge achievement that in a country this big and this diverse we have an active TB rate of just 2.5 per 100,000 (2), but we need to be doing targeted testing for latent tuberculosis.

And the way to do that should never be to target a population of individuals and treat them differently – it's to look at the model of success from healthcare, and translate that into other professions.

Bringing down the rates of latent TB

According to the Centers for Disease Control and Prevention (CDC), all U.S. health care personnel should be screened for TB upon hire (3). That’s had great results, so why aren’t we widening that out? Most people in America are employed, and most will have an occupational health professional who they’re potentially interacting with more than their primary care doctor.

If we can look at other occupations where the rates – or risks – of transmission are higher and ask those employers to do one-time TB testing on hire like we do in healthcare, it could change everything. As well as the huge public health gains, it keeps workers and customers safe and protects employers from possible worker compensation claims. Why has legislation and regulation focused almost exclusively on healthcare and corrections workers, when we know from CDC data that a huge percentage of active TB occurs in employees outside of those roles. It seems absurd.

We can look at the occupations that had higher transmission rates for COVID –  another airborne respiratory disease – and start introducing TB testing into occupational health there. If we identify these people while they're young and healthy then we’re not waiting 20 years until they reactivate and infect other people, and we will get to elimination in the U.S.

Operationally it makes sense – we don't send everybody to the public health department, we use the occupational health specialists who are already in place. They’re already doing pre-employment physicals on people, so we just add the TB test to that. It’s a game changer not just for the employees’ own health and the safety of the public, but also for the company itself. We could eliminate it in a profession –  meat packers, airline pilots – and it would be a domino effect.

So what’s stopping us? Right now what’s lacking is regulation, education and funding – who makes the rules, who pays for the testing, and who pays for the treatments. So our policy-makers really need to understand the public health imperative of testing workers before they sit in that cockpit or shared office or enclosed space.  

We eliminate in this location, this profession, until we get all the dominoes across America to fall, and meat and poultry processing plants would be a great place to start. There have been repeated active TB outbreaks involving ten or more cases for decades, but it came into sharp relief when COVID ravaged those workers at a far higher rate than the general population – at one large plant the risk was found to be 70 times higher (4). It’s not difficult to work out why – these are people working in hot, humid areas with poor air quality and loud machinery that means yelling at close range to make yourself heard. So why aren’t we doing more to protect their health? It’s scandalous.

Meat and poultry workers also tend to be non-U.S. born, with some plants hosting workers from more than 40 countries. Universities and the tech industry also often recruit from very high-burden regions, so targeting those sectors could also pay real societal dividends.

So what we need to do is move away from reacting to active TB – we could easily have caught most of those people while they were at work.

Life’s too short for inefficiencies

The Global End TB Strategy is aiming for 90% reduction in deaths by the end of the decade and an 80% reduction in incidence (5). I don’t know if we’ll achieve that, but I’d love to see it happen.

What I can do, however, is address the situation North America. If we test and treat appropriately for latent TB, then we can eliminate active TB in the U.S. But it’s more than the right diagnosis – you have to get that diagnosis efficiently. It doesn't make sense to waste people’s time and money – just do the right test the first time, then treat.

I'm a huge believer in policy as a way to change the world. When you can put a policy in place that’s effective and guarantees the best use of resources, it feels good. Life’s too short for inefficiencies. 

So I know we can eliminate TB in the United States – but it has to be with the right diagnostic used in the right population, the right setting, and followed immediately by the right treatments. I have no doubt we can do it, but it's going to take a paradigm shift.

I’d like to see the language change so we’re not always talking about treating latent TB. Public health is about prevention, and what we’re talking about is preventing active TB.

We can eliminate it, and I'd like to be part of that.