The burden of TB amid the climate crisis

July 31, 2025

Medical MRI Scan on digital screen — Image: © da-kuk | iStock

Extreme weather events, the increasing threat of antimicrobial resistance, and other global challenges are impacting the prevalence and fight against tuberculosis. Open Access Government examines the burden of TB, looking at the origins and drivers of this ubiquitous disease

Tuberculosis (TB) is an infectious bacterial disease that affects approximately ten million people each year. Although the disease is both preventable and curable, more than a million people are estimated to die each year as a result of infection.

TB is spread through the air or via water droplets, typically through close contact with contagious individuals. About a quarter of the global population is estimated to have been infected with the bacteria Mycobacterium tuberculosis, but only around 5-10% of those infected eventually develop symptoms. Many infected people have what is referred to as ‘latent TB’, whereby the disease lies dormant in their system; the bacteria are surrounded by granulomas – small immune cells – that prevent the disease from spreading, and thus the carrier exhibits no symptoms and is not contagious. Conversely, if a person’s immune system is compromised, they can develop ‘active TB’ and thereby become contagious and susceptible to illness.

Although tuberculosis is more prevalent in low- and middle-income countries, it is found in every country and can affect individuals of all ages. Additionally, case numbers in high-income countries have been increasing; for instance, in England, cases rose by 13% in 2024 compared to 2023, surpassing the levels seen before the COVID-19 pandemic. The World Health Organization (WHO) reports that TB is likely the leading cause of death from a single infectious agent worldwide, a position it regained after being surpassed by coronavirus disease (COVID-19) for three years.

Who is most at risk from TB?

TB is the primary killer of individuals living with HIV and is a significant contributor to deaths resulting from antimicrobial resistance (AMR). Other at-risk groups include people with diabetes, a weakened immune system, who use tobacco, excessive alcohol, or suffer from malnourishment.

Over 80% of TB cases and deaths occur in low- and middle-income countries. Figures from the WHO indicate that in 2023, the highest number of new TB cases was reported in the WHO South-East Asia Region (45%), followed by the African Region (24%) and the Western Pacific Region (17%). Approximately 87% of new TB cases arise from the 30 countries with the highest TB burden, with more than two-thirds of the global total stemming from Bangladesh, China, the Democratic Republic of the Congo, India, Indonesia, Nigeria, Pakistan, and the Philippines.

Around 3.6 billion people, mainly in Africa and Southeast Asia, live in areas that are highly vulnerable to climate change and therefore face a significant burden of TB. This region accounted for about 69% of the global incident cases of TB in 2023.

How does climate change impact TB?

The link between population health and the health of the planet is a topic that is increasingly being addressed by policy leaders worldwide. So much so that for the first time, health led the conversations at the 28th United Nations Climate Change Conference (COP28). Shifting environmental conditions – from wildfires, flooding, and air pollution – can have far-reaching impacts on people’s lives as well as the burden of TB. For communities already facing socioeconomic and healthcare inequities, this makes disease spread and access to vital diagnostics and treatment all the more challenging.

In a recent WHO report, authors identified three significant pathways contributing to TB’s transmission and progression as a result of environmental changes: migration and displacement, food and water insecurity, and health system disruption. Increased migration and displacement as a result of climate factors can hinder access to healthcare and increase TB transmission due to greater exposure; food and water insecurity means communities’ immune function can become impaired, therefore making them more susceptible, and reduced access to healthcare means delays in diagnosis and poorer health outcomes.

Early intervention is crucial for managing many transmissible diseases. As climate disasters become more frequent, health systems must be strengthened to be resilient and ensure that supply chain infrastructures can endure disruptions, allowing care to reach those who need it. It is projected that climate change will lead to an estimated 250,000 deaths globally each year between 2030 and 2050 due to increased cases of malnutrition, malaria, diarrhoea, and heat stress.

The global response

The World Health Organization’s post-2015 End TB Strategy, which was adopted by the World Health Assembly in 2014, aims to eliminate the global tuberculosis (TB) epidemic as part of the broader Sustainable Development Goals. Since the year 2000, global efforts to combat TB have contributed to saving an estimated 79 million lives annually. To achieve the target of reaching 90% of individuals with TB prevention and care services by 2027, an annual funding of $22 billion is required. International donor funding is therefore vital.

Further efforts to encourage collaborative efforts in the fight against TB included the inaugural Health Day, co-hosted by the COP28 Presidency, WHO, and other partners. This event focused on the connection between climate change and human health, the health benefits of climate mitigation, and the importance of strengthening health system resilience. Global leaders endorsed a declaration calling for action to address the health impacts of climate change.

It is clear that to effectively address the multifaceted challenges of climate change and its impact on health, international collaboration across various sectors will be crucial in mitigating the TB epidemic.