There were three great pandemics in the 20th century. The influenza pandemic of 1918 and the HIV pandemic during the 1980s and 1990s get the most attention. But the third, tuberculosis, was the deadliest by far and in many communities, it’s not yet over.
TB has much to teach us about the tools that can help to eradicate the current pandemic, and what happens when those tools aren’t even tried. The disease killed more than one billion people between 1800 and 2000. Although it is caused by a bacterium rather than a virus, the disease shares some frightening similarities with this current coronavirus.
The pathogen that causes TB is airborne, transmitted from person to person in households and social spaces. People with TB spread the bacteria to new individuals when they breathe. Only half of those with TB display symptoms, allowing the deadly disease to spread undetected. And like today, the most vulnerable people are hit the hardest — older people, those with underlying conditions and people living in poverty.
A century ago, TB was a terrifying reality for people all over the world. One in every nine deaths in the United States in 1906 was caused by tuberculosis (adjusted to our current population levels, this would be the equivalent of 540,000 Americans dying of TB every year). The disease killed as many people as cancer and diabetes, causing profound damage to economic and social life.
Yet by the 1970s, rates of tuberculosis had dropped markedly in the US and other wealthy countries. How was this achieved? With the help of diagnostic treatments, the US pursued a successful strategy called “search, treat and prevent”. The key innovation wasn’t drugs (although antibiotics helped eradicate the disease, the first antibiotic treatment for TB was demonstrated in the 1940s, by which time cases of the disease had already fallen to around a fifth of 1906 levels). What made a huge difference was a community-based approach where people joined together to stop the spread of disease.
The first step was freeing the sick of social and financial burdens. This allowed them to come forward for testing, care and support, without having to keep working and spreading the disease in the process. To this day, some of the only free health services available to everyone in the US are those relating to tuberculosis.
Health authorities in the US went door to door searching for those who were sick and tracing people they had contacted. They treated sick people with food, medicine and shelter, and offered preventative therapies to stop others from becoming sick. Free TB care was only made possible through stable financing and community support, and cooperation between governments, employers, unions, faith groups and communities. Government financing and a community-based strategy were the key advances that made it possible to eradicate TB.
But in many poor countries struggling with the pernicious legacy of colonialism, concerns about the cost of treatment trumped overwhelming scientific evidence. Instead of identifying and treating cases of TB across the population, these countries treated only the sickest and most infectious people. Focusing on the most extreme cases made sense, but it did little to stop the spread of the disease among asymptomatic carriers. In poorer countries, the results have been devastating: TB is the biggest infectious killer of adults globally, and continues to kill on average 4,000 people every day, mostly outside wealthy countries.
These different approaches to treating TB can teach us much about the right and the wrong way to stop Covid-19. One of the main things we learned from TB is that epidemics can’t be beaten in hospitals alone. Eradicating a disease like this has to take place in the community. Treating Covid-19 will depend on community testing, either across a population or by using methods of cluster sampling. There are multiple ways to curb community transmission of the disease – from face masks that prevent people from spreading particles that carry germs, to physical distancing measures and self isolation. We should also be examining how existing technologies, such as germicidal ultraviolet lighting and vaccines that we already have at our disposal could help protect against the transmission of Covid-19.
Crucially, we shouldn’t wait for a killer app or a vaccine to treat the coronavirus. Effective antibiotics weren’t discovered until years after TB had receded in affluent countries. Covid-19 might be different; if it behaves like other coronaviruses, those who have been infected may become immune. But the quest for a “silver bullet” shouldn’t detract from interventions already known to work.
The fight against tuberculosis showed that treating a pandemic only in one part of the world isn’t enough to eradicate a disease. An estimated two-thirds of tuberculosis cases in wealthy countries today originate in places where a comprehensive response to TB was never implemented. Defeating a pandemic requires a global commitment.
But the key to a successful community-based strategy isn’t just case-finding or quarantine, though they will both play a role. It’s trust. Why is trust so important? With TB, as with Covid-19, more than half of the people with the disease exhibit no symptoms. If people do not come forward to be treated, and don’t consent to be tested, or if they are unable and therefore unwilling to remain isolated, the process of treating the disease can’t even begin.
People must be able to trust that they won’t individually bear the catastrophic health expenses incurred from fighting the virus. This means providing housing and employment support for everyone who needs to isolate, and ensuring that people who are sick or isolating don’t forgo their wages to do so. If the economic and social risks of Covid-19 aren’t shared across the population, the next wave of the pandemic could be dramatically worse. It’s only through mutual trust that we will find those infected with coronavirus, help the sick recover and halt its spread.
Ensuring that countries across the world have the resources to pursue a strategy of testing, treating and preventing the virus will be far less costly than the effects of another outbreak on the global economy. We know from history that this is the only way to stop the virus in its tracks.
• Salmaan Keshavjee is the director of the Harvard Medical School Centre for Global Health Delivery. Aaron Shakow is a research associate in global health and social medicine at Harvard Medical School. Tom Nicholson is a research associate at Duke University’s Sanford School of Public Policy