Mycobacterium tuberculosis is a near-perfect predator. In 1882, Robert Koch, the physician who discovered the microbe, told a room full of scientists that it caused one in seven of all deaths. In 2023, after a brief hiatus, tuberculosis regained from COVID its status as the world’s deadliest infectious disease—a title it has held for most of what we know of human history.

Some people die of TB when their lungs collapse or fill with fluid. For others, scarring leaves so little healthy lung tissue that breathing becomes impossible. Or the infection spreads to the brain or the spinal column, or they suffer a sudden, uncontrollable hemorrhage. Lack of appetite and extreme abdominal pain can fuel weight loss so severe that it whittles away muscle and bone. This is why TB was widely known as “consumption” until the 20th century—it seemed to be a disease that consumed the very body, shrinking and shriveling it. On a trip to Sierra Leone in 2019, I met a boy named Henry Reider, whose mix of shyness and enthusiasm for connection reminded me of my own son. I thought he was perhaps 9 years old. His doctors later told me that he was in fact 17, his body stunted by a combination of malnutrition and tuberculosis.

The cure for TB—roughly half a year on antibiotics—has existed since the 1950s, and works for most patients. Yet, in the decades since, more than 100 million people have died of tuberculosis because the drugs are not widely available in many parts of the world. The most proximate cause of contemporary tuberculosis deaths is not M. tuberculosis, but Homo sapiens. Now, as the Trump administration decimates foreign-aid programs, the U.S. is both making survival less likely for people with TB and risking the disease becoming far more treatment-resistant. After decades of improvement, we could return to something more like the world before the cure.

[Read: The danger of ignoring tuberculosis]

Anyone can get tuberculosis—in fact, a quarter of all humans living now, including an estimated 13 million Americans, have been infected with the bacterium, which spreads through coughs, sneezes, and breaths. Most will only ever have a latent form of the infection, in which infection-fighting white blood cells envelop the bacteria so it cannot wreak havoc on the body. But in 5 to 10 percent of infections, the immune system can’t produce enough white blood cells to surround the invader. M. tuberculosis explodes outward, and active disease begins.

Certain triggers make the disease more likely to go from latent to active, including air pollution and an immune system weakened by malnutrition, stress, or diabetes. The disease spreads especially well along the trails that poverty has blazed for it: in crowded living and working conditions such as slums and poorly ventilated factories. Left untreated, most people who develop active TB will die of the disease.

In the early 1980s, physicians and activists in Africa and Asia began sounding the alarm about an explosion of young patients dying within weeks of being infected instead of years. Hours after entering the hospital, they were choking to death on their own blood. In 1985, physicians in Zaire and Zambia noted high rates of active tuberculosis among patients who had the emerging disease now known as HIV/AIDS. TB surged globally, including in the U.S. Deaths skyrocketed. From 1985 to 2005, roughly as many people died of tuberculosis as in World War I, and many of them also had HIV. In 2000, nearly a third of the 2.3 million people who died of tuberculosis were co-infected with HIV.

[Read: Tragedy would unfold if Trump cancels Bush’s AIDS program]

By the mid-1990s, antiretroviral cocktails made HIV a treatable and survivable disease in rich communities. While a person is taking these medications, their viral levels generally become so low as to be undetectable and untransmittable; if a person with HIV becomes sick with tuberculosis, the drugs increase their odds of survival dramatically. But rich countries largely refused to spend money on HIV and TB meds in low- and middle-income countries. They cited many reasons, including that patients couldn’t be trusted to take their medication on time, and that resources would be better spent on prevention and control. In 2001, the head of the U.S. Agency for International Development had this to say when explaining to Congress why many Africans would not benefit from access to HIV medications: “People do not know what watches and clocks are. They do not use Western means for telling time. They use the sun. These drugs have to be administered during a certain sequence of time during the day and when you say take it at 10:00, people will say, ‘What do you mean by 10:00?’” A 2007 review of 58 studies on patient habits found that Africans were more likely to adhere to HIV treatment regimens than North Americans.

In the mid-2000s, programs such as PEPFAR and the Global Fund finally began distributing antiretroviral therapy to millions of people living with HIV in poor countries. PEPFAR, a U.S.-funded initiative, was especially successful, saving more than 25 million lives and preventing 7 million children from being born with HIV. These projects lowered deaths and infections while also strengthening health-care systems, allowing low-income countries to better respond to diseases as varied as malaria and diabetes. Millions of lives have been saved—and tuberculosis deaths among those living with HIV have declined dramatically in the decades since.

Still, tuberculosis is great at exploiting any advantage that humans hand it. During the coronavirus pandemic, disruptions to supply chains and TB-prevention programs led to an uptick in infections worldwide. Last year, the U.S. logged more cases of tuberculosis than it has in any year since the CDC began keeping count in the 1950s. Two people died. But in some ways, at the beginning of this year, the fight against tuberculosis had never looked more promising. High-quality vaccine candidates were in late-stage trials. In December, the World Health Organization made its first endorsement of a TB diagnostic test, and global health workers readied to deploy it.

[Read: America can’t just unpause USAID]

Now that progress is on the verge of being erased. Since Donald Trump has taken office, his administration has dismantled USAID, massively eliminating foreign-aid funding and programs. According to The New York Times, hundreds of thousands of sick patients have seen their access to medication and testing suddenly cut off. A memo released by a USAID official earlier this month estimated that cases of multidrug-resistant tuberculosis will rise by about 30 percent in the next few years, an unprecedented regression in the history of humankind’s fight against the disease. (The official was subsequently placed on administrative leave.) Research on tuberculosis tests and treatments has been terminated. Although the secretary of state and Elon Musk have assured the public that the new administration’s actions have not disrupted the distribution of life-saving medicine, that just isn’t true. A colleague in central Africa sent me a picture of TB drugs that the U.S. has already paid for sitting unused in a warehouse because of stop-work orders. (Neither the State Department nor DOGE employees responded to requests for comment.)

Last year, roughly half of all international donor funding for tuberculosis treatment came from the U.S. Now many programs are disappearing. In a recent survey on the impact of lost funding in 31 countries, one in four organizations providing TB care reported they have shut down entirely. About half have stopped screening for new cases of tuberculosis. The average untreated case of active tuberculosis will spread the infection to 10 to 15 people a year. Without treatment, or even a diagnosis, hundreds of thousands more people will die—and each of those deaths will be needless.

By revoking money from global-health efforts, the U.S. has created the conditions for the health of people around the world to deteriorate, which will give tuberculosis even more opportunities to kill. HIV clinics in many countries have started rationing pills as drug supplies run dangerously low, raising the specter of co-infection. Like HIV, insufficient nutrition weakens the immune system. It is the leading risk factor for tuberculosis. An estimated 1 million children with severe acute malnutrition will lose access to treatment because of the USAID cuts, and refugee camps across the world are slashing already meager food rations.

For billions of people, TB is already a nightmare disease, both because the bacterium is unusually powerful and because world leaders have done a poor job of distributing cures. And yet, to the extent that one hears about TB at all in the rich world, it’s usually in the context of a looming crisis: Given enough time, a strain of tuberculosis may evolve that is resistant to all available antibiotics, a superbug that is perhaps even more aggressive and deadly than previous iterations of the disease.

[Read: Resistance to the antibiotic of last resort is silently spreading]

The Trump administration’s current policies are making such a future more plausible. Even pausing TB treatment for a couple of weeks can give the bacterium a chance to evolve resistance. The world is ill-prepared to respond to drug-resistant TB, because we have shockingly few treatments for the world’s deadliest infectious disease. Between 1963 and 2012, scientists approved no new drugs to treat tuberculosis. Doing so stopped being profitable once the disease ceased to be a crisis in rich countries. Many strains of tuberculosis are already resistant to the 60-year-old drugs that are still the first line of treatment for nearly all TB patients. If a person is unlucky enough to have drug-resistant TB, the next step is costly testing to determine if their body can withstand harsh, alternative treatments. The United States helped pay for those tests in many countries, which means that now fewer people with drug-resistant TB are being diagnosed or treated. Instead, they are almost certainly getting sicker and spreading the infection.

Drug-resistant TB is harder to cure in individual patients, and so the aid freeze will directly lead to many deaths. But giving the bacteria so many new opportunities to develop drug resistance is also a threat to all of humanity. We now risk the emergence of TB strains that can’t be cured with our existing tools. The millennia-long history of humans’ fight against TB has seen many vicious cycles. I fear we are watching the dawn of another.

This article has been adapted from John Green’s forthcoming book, Everything Is Tuberculosis.

The Founders knew that Americans, for better or worse, had an insatiable desire for overseas trade. “They are as aquatic as the tortoises and sea-fowl,” observed John Adams, “and the love of commerce, with its conveniences and pleasures, is a habit in them as unalterable as their natures.” As early as 1785 he foresaw that Americans would be compelled to form “connections with Europe, Asia, and Africa,” and he advised that “the sooner we form those connections into a judicious system, the better it will be for us and our children.” Thomas Jefferson would have preferred to cease all commerce with the rest of the world and rely on the simple virtues of the “yeoman farmer,” but he knew this was impossible. “Our people have a decided taste for navigation and commerce … and their servants are in duty bound to calculate all their measures on this datum.” Even that much-caricatured “Jacksonian,” Andrew Jackson himself, as president never fired a shot in anger but negotiated more trade agreements with foreign powers than any of his predecessors.

The American love of trade made using the practice as a weapon against other nations difficult. When Jefferson forgot his own lesson and tried to embargo trade with Great Britain in 1807 in response to the British navy’s abuse of American merchants on the high seas, his efforts backfired, stirring talk of secession in the New England states that conducted most of that trade. It turned out to be easier to get Americans to support a shooting war with Great Britain than a trade war.

Donald Trump is now learning the hard way how vulnerable America is when it comes to trade wars. This is not because the United States doesn’t in theory hold the strongest hand. The American market is the most desired in the world, and any restriction on access to that market should hurt other countries more than it hurts the United States. The ratio of international trade to GDP for the U.S. is roughly 25 percent, compared with more than 60 percent on average for all other nations. In Germany, foreign trade tallies up to 90 percent of GDP. That ought to make the country vulnerable and give the United States leverage. In practice, however, Americans have proved time and again that they have a very low threshold of pain when it comes to trade wars. Jefferson was not wrong to believe that Britain depended heavily on American trade when he launched his embargo in 1807; what he did not anticipate was that his own citizens would cave before Britain did.

[Read: How Republicans learned to love high prices]

The problem is, or at least has been up until now, democracy, and, more specifically, electoral politics in a federal system where narrow, local interests can have broad national political impact. A trade dispute might harm only one sector of the economy, but if that sector happens to coincide with a crucial voting bloc, it can put the United States at a disadvantage in a contest with a nominally weaker power.

A good example of this came during World War I, before the United States had entered the war and Woodrow Wilson was trying to navigate his way through British blockades and German submarine attacks on transatlantic shipping while desperately trying to preserve American neutrality. The United States was far less reliant on international trade then; it was only 11 percent of GDP. But as Wilson learned, even damage to particular sectors of the economy could threaten political upheaval. Although his personal inclinations were pro-British, for instance, London’s threats to blockade cotton as contraband of war infuriated the Democrats’ key southern constituency. Wilson’s secretary of the Treasury, William Gibbs McAdoo, recalled spending “more sleepless nights thinking about cotton” than about anything else during his time in office. The rest of his sleepless nights were spent worrying about finding markets for midwestern grain, much of which had been purchased by Germany and other European nations prior to the war. These specific sectors, because they involved states and regions essential to national political coalitions, had influence on American decision making that exceeded their overall importance to the American economy.  

[Read: Trump’s most inexplicable decision yet]

Trump must believe, as Jefferson did, that the world needs America more than America needs the world, and he may be right—in theory. The problem is that individual voting blocs mean more to him than carrying out a consistent trade war, as he has repeatedly demonstrated during both terms in office. In his first term, the damage done to farmers by his tariffs on imports was sufficiently threatening politically that he had to spend much of the money gained by the tariffs to compensate the farmers for their losses. His vacillations and emendations in his latest rounds of tariffs this year have been similarly motivated by his desire not to alienate Republican voters in particular states—northern-tier states that rely heavily on trade with Canada and automaking states that stand to lose badly from tariffs on auto parts, steel, and aluminum crossing the Mexican and Canadian borders. It is no accident that among the Europeans’ first retaliatory tariffs have been those against Harley-Davidson and American whiskey. Other nations may know their history better than Trump does and have figured out that tariffing sectors of the economy that hit Trump voters can have an impact beyond their dollar value. The United States is a nation split down the middle politically, so marginal voting groups can have a huge effect. This significantly vitiates the American advantage.

It would be one thing if Trump’s supporters were willing to suffer economic hardship in order to show their support for the MAGA way. As Senator Tommy Tuberville of Alabama put it, “There’s going to be some pain with tariffs,” but “no pain, no gain.” The problem for Trump is that, so far, as in the past, even his own voters don’t have much tolerance for pain.