As the global fight against tuberculosis falters, a more formidable threat is quietly advancing: Extensively Drug-Resistant Tuberculosis, or XDR-TB. With critical funding drying up to find and treat drug-resistant cases, the world is veering off course from the U.N. Sustainable Development Goal to eliminate TB by 2030—barreling instead toward a looming, preventable public health emergency.

XDR-TB is a severe form of TB that doesn’t respond to the most powerful medicines usually used to treat the disease. It develops when regular TB or drug-resistant TB isn’t treated properly, allowing the bacteria to become even more resistant over time—making the illness harder to cure and more dangerous to others.

TB strains identified in Cambodia between 2012 and 2017 already include the Beijing genotype, of which one is named XDR+, and resistant to all known treatments. This is indeed alarming.

In 2023, Cambodia reported 213 cases of drug-resistant TB—up from 127 the year before—a rise that likely reflects better detection and reporting, with support from international donors, rather than a sudden surge in infections. Encouragingly, treatment outcomes have steadily improved, with 83 percent of patients from the 2020 cohort completing treatment successfully, compared to just 64 percent in 2016.

But these hard-won gains are now at risk. The abrupt withdrawal of U.S. funding for TB surveillance in early 2025 has left a dangerous vacuum—just as extensively drug-resistant TB begins to spread, often undetected and untreated.

The $15 million cut by USAID was not symbolic—it dismantled TB defenses. Active case finding ceased in half the country. Around 100,000 people missed screenings, and 25,000 likely went undiagnosed including some 300 drug-resistant cases. Portable X-ray procurement and contact tracing ended. Preventive therapy for thousands was halted. And the backbone of Cambodia’s TB surveillance, Cam TBMIS, lost support.

Cam TBMIS is the National TB Program's tool for collecting case-based data, particularly for drug-resistant Tuberculosis (DR-TB). It's an electronic TB Management Information System (MIS) that was designed to replace a paper-based system, improving the efficiency and accuracy of TB data management.

This is not a temporary setback. It’s a systemic unravelling, one that jeopardizes human lives.

Weak Health Systems and Overcrowded Prisons

TB kills over a million people annually. But XDR-TB raises the stakes. Treatment takes up to two years, a substantially longer period than the standard 6-month regimen for drug-susceptible TB, with severe side effects and success rates hovering around 39 percent.

In Cambodia, health systems are still weak and uneven access to care mean that missing even one case of TB can have serious consequences for the entire country. It's estimated that more than 40 percent of people with TB in Cambodia go undiagnosed. This shows a major gap in the country’s ability to detect and track the true scale of the disease.

There are many reasons for this. Some people don’t seek medical care when they first show symptoms. Others live in areas where TB testing or treatment isn’t available. Even when care is available, it isn’t always easy to reach or affordable. Many people with TB symptoms turn first to private clinics, which often aren’t connected to the national TB program. This can delay diagnosis and treatment—and in some cases, it means cases aren’t reported at all.

The situation is made worse by two major risk factors: the spread of HIV and overcrowded prisons.

In Cambodia’s prison system, TB is four to six times more common than in the general population. Poor ventilation and overcrowding make it easy for the disease to spread. Many prisoners already carry latent TB when they arrive, and they may leave prison with drug-resistant forms that were never properly diagnosed or treated. Once released, they can pass the disease to others—especially if they don’t continue treatment.

HIV is another serious concern. It weakens the immune system, making it easier for TB to become active and harder to treat. Many people with TB in Cambodia are also living with HIV, although the exact number varies between studies. These patients are especially vulnerable. If their TB isn’t diagnosed quickly or treated correctly, they can get very sick and die. Managing both diseases together is also harder. HIV can make it difficult to take TB medications consistently or handle the side effects.

This dangerous combination—HIV and TB—creates the perfect conditions for XDR-TB to develop and spread. When care is delayed or interrupted, and when people are already weakened by other illnesses, drug-resistant TB becomes even harder to control.

The Knock-On Effects of Neglect

Treating XDR-TB puts intense pressure on Cambodia’s already limited health system. The regimens are longer, come with severe side effects, and cost far more than treatment for drug-susceptible TB. In 2015, there were only 65 airborne isolation beds available across the country, making effective care not just difficult—but nearly impossible.

Although the exact number of isolation beds in Cambodia as of 2025 remains unclear, the country had made important strides in expanding its capacity to treat Multi-Drug Resistant TB (MDR-TB) through community-based programs—shifting away from an overwhelming dependence on hospital isolation beds. But that fragile progress is now at risk.

The abrupt gutting of USAID funding led to the dismissal of approximately 5,000 community health workers and 200 field staff from KHANA, a key NGO in Cambodia’s TB response. These frontline workers were not just numbers—they were lifelines, providing vital education, screening, and treatment support in 27 districts across nine provinces. Their sudden absence has left countless communities exposed, with no safety net to catch them. TB services have been interrupted, and with them, the hope of containing the spread of this devastating disease.

For families, the economic burden is equally harsh. Despite free TB services, the indirect costs—travel, lost income, nutrition—are often catastrophic. A Cambodian study showed MDR-TB expenses can exceed three times a household’s annual income. For XDR-TB, the financial impact is even worse, pushing families into debt or forcing them to abandon treatment altogether.

When treatment is delayed or incomplete, bacteria evolve. Each failure increases the chance of even more resistant strains emerging. This is how “pan-resistant” TB—resistant to all drugs—becomes a global reality. Cambodia’s weak detection system, under-resourced due to U.S. cuts, gives drug-resistant TB and XDR-TB a perfect environment to thrive and spread.

The crisis is deepened by a growing loss of public trust. When patients watch friends die despite being "on treatment," or are turned away from clinics due to understaffing or medication stockouts, they lose faith in the system. Many delay seeking care—or turn to unregulated providers. These delays not only prolong infectious periods but also increase the risk of drug resistance.

Yet Cambodia had been making meaningful strides. It had graduated from the WHO’s list of high-burden TB countries. It pioneered community-based care for MDR-TB, introduced digital systems for case notifications, and participated in global research initiatives like CAM-ShORRT to pilot all-oral treatment regimens.

The data from CAM-ShORRT was poised to strengthen the global evidence base and inform drug-resistant TB treatment in countries grappling with limited resources, high disease burden, and fragile health systems. But that progress rested on a precarious foundation—one heavily dependent on international aid to sustain research, diagnostics, and access to treatment.

The sudden withdrawal of U.S. funding laid bare the fragility of Cambodia’s tuberculosis response infrastructure. Without swift, sustained reinvestment—and a firm financial commitment from both international donors and the Cambodian government—the country risks becoming one of the centers of a global resurgence, not only of TB but of its most lethal and drug-resistant strains. And TB doesn’t respect borders—what festers in Phnom Penh today could easily surface tomorrow in Singapore, Sydney, or San Francisco.

Extensively drug-resistant TB (XDR-TB) is not just a public health issue—it’s a global security threat. If COVID-19 taught the world anything, it’s that hesitation in the face of infectious disease can be catastrophic. Delayed action costs lives. TB — especially in its drug-resistant forms—requires the same level of urgency, coordination, and funding we saw mobilized during the pandemic.

The world pledged to end TB by 2030, but that goal is slipping further out of reach with the emergence of XDR-TB. The next pandemic might not come from a novel virus—it could be an old enemy, a once-treatable bacterium that evolved in the shadows while we looked away.