Commentary: We’re losing ground in the global fight against tuberculosis

SINGAPORE: Most of us are likely more concerned by the diseases of modern living such as cardiovascular disease, diabetes and dementia. Few realise that tuberculosis (TB) has been the world’s deadliest infectious disease for decades – claiming over 1 million lives every year, briefly surpassed only by COVID-19.

The number of deaths has resumed its slow decline thanks to global efforts. But the United States’ recent drastic foreign aid cuts now threaten to reverse close to three decades of gains – and trigger a global health crisis.

The US has played an outsized role in global TB control, through its foreign aid agency USAID which is being gutted by the Trump administration.

USAID began its global TB control programme in 1998, providing funding and support to high-burden TB countries. When the Global Drug Facility for TB was launched in 2021 to procure high-quality anti-TB drugs and diagnostics for low- and middle-income countries, USAID also played a crucial funding role to ensure access.

In 2024 alone, the US directly contributed an estimated US$406 million for TB control – nearly a quarter of all global donor funding. It is also the largest donor to the Global Fund to Fight AIDS, Tuberculosis and Malaria that provides over 60 per cent of all donor funding for TB. For now, the silver lining is that US contributions to the Global Fund have not yet been officially cut.

WHAT THIS MEANS FOR ASIA

Asia, in particular, will feel the impact. The top five high-burden TB countries account for over half of all cases worldwide, and all are in Asia: India (26 per cent of global cases in 2023), Indonesia (10 per cent), China (6.8 per cent), the Philippines (6.8 per cent) and Pakistan (6.3 per cent).

The US supports TB control efforts to varying degrees in Cambodia, Indonesia, Myanmar, Philippines, Vietnam, Bangladesh, India and Pakistan. For some of these countries, the combined USAID and Global Fund contributions exceed domestic TB control budgets.

Their and other low- and middle-income countries’ heavy reliance on US foreign aid means – as World Health Organization Director-General Dr Tedros Adhanom Ghebreyesus warned on Mar 17 – that they are “facing crippling breakdowns in their [TB] response”.

Already, nine countries have reported failing supply chains for anti-TB drugs. The consequences are a short- and medium-term rise in TB cases and deaths as health workers are laid off, diagnosis rates fall, and the supply of anti-TB drugs becomes intermittently interrupted. Drug-resistant TB cases may also increase significantly.

These countries cannot easily cover the funding shortfall by reallocating funds from other health programmes such as HIV, malaria, childhood vaccination and nutrition – these are often supported by the US and also facing similar cuts. Governments now face terrible choices in these health priorities.

SINGAPORE IS NOT IN THE CLEAR

The unfolding TB crisis in the broader region is unlikely to bypass Singapore, even though it has a well-established and successful TB control programme.

Local TB incidence has decreased by over tenfold since pre-independence years to 28.9 cases per 100,000 population in 2023. Singapore has never received foreign funding for TB control since independence.

But Singapore is heavily reliant on migrant workers. Most domestic helpers and workers in construction, marine shipyard and process sectors come from high-burden TB countries. A significant proportion of the skilled foreign workforce, including nurses, also hail from these countries.

When TB control programmes deteriorate in these countries, the risk of import and spread in Singapore also increases.

Currently, migrant workers are screened for active TB disease with a chest X-ray as part of their medical examination prior to being issued their work permits. This screening is repeated every two years that they spend in Singapore as a condition for work permit renewal.

When abnormalities are detected, further evaluation is conducted for TB and other lung diseases. Suspected TB cases are either treated at the National TB Care Centre at Tan Tock Seng Hospital or repatriated.

It is likely that there is considerable over-diagnosis and over-treatment of TB in this population – out of an overabundance of caution.

REVISITING THE RISKS OF LATENT TB INFECTION

However, Singapore does not currently screen migrant workers for latent TB infection.

Unlike influenza or measles, virtually all individuals infected by the bacterium do not immediately develop TB disease. Their immune systems suppress but are not able to eliminate the bacterium.

The majority will remain well and in this state for the rest of their lives, oblivious to the infection. However, about one of every 10 such individuals will develop symptomatic disease , when their immune system weakens or even when they are under psychosocial stress. At this stage, unless diagnosed and treated early, they may spread TB to others.

Although there are tests and effective treatment for latent TB, the former are expensive, generally exceeding S$90 (US$67). Prior evaluations have shown that screening for latent TB will not be cost-effective for migrant workers coming to Singapore unless they stay on for many decades.

This may need to be re-evaluated if – as is likely – TB rates rise in the region, particularly if more cases of drug-resistant TB appear.

A COLLECTIVE FIGHT

The US administration’s foreign aid cuts are currently undergoing judicial challenge in the federal courts. But even in the unlikely scenario that these cuts are eventually reversed, the damage has already been done.

We are likely to see the past decade’s progress in global TB control reversed, and the aspirational goal of TB elimination become more Sisyphean.

There may still be reason for optimism. The global resolve to eliminate TB remains strong, and thus may yet be translated into regional cooperation and proactive policies. Singapore can contribute, not just by continuing to drive down local TB incidence, but also by sharing expertise and investing more in research and innovation.

Ultimately, collective action and sustained commitment is necessary in the fight against TB. Infectious diseases don't stop at borders – neither should our response.

Professor Hsu Li Yang is Director, Asia Centre for Health Security at the Saw Swee Hock School of Public Health, National University of Singapore.