Tuberculosis (TB) is one of the world’s deadliest infectious diseases, claiming millions of lives each year. Despite considerable medical advancements over the last century, TB remains a major global health challenge, particularly in low- and middle-income countries. Explore the nature of tuberculosis in this article, alongside its history, current prevalence, challenges in controlling its spread, and ongoing efforts to eradicate the disease.
What is Tuberculosis
Tuberculosis (TB) is a bacterial infection caused by Mycobacterium tuberculosis, primarily affecting the lungs. It is transmitted through airborne particles that spread when an infected person coughs, sneezes or speaks. TB is most easily transmitted in crowded and poorly ventilated environments¹, such as hospitals, prisons and nursing homes. Although the disease occurs worldwide, its prevalence is higher in regions such as Asia, Africa and Latin America². The incidence of newly diagnosed TB in Singapore is 1156 cases (in 2024) according to Ministry of Health.
Types of Tuberculosis
Tuberculosis can be classified into several types based on its location and severity. While TB commonly affects the lungs (pulmonary TB), it can also affect other organ systems, such as the lymph nodes, kidney or spine. This form is known as extrapulmonary TB. Although it is less contagious than pulmonary TB, it is often more challenging to diagnose, and considered more dangerous due to the possibility of rapid progression³.
In terms of severity, tuberculosis can be categorised as follows:
- Latent Tuberculosis: Latent tuberculosis refers to when Mycobacterium tuberculosis bacteria that are present in the body but remain inactive. During this stage, the immune system works to control the infection by containing the bacteria within a protective barrier known as the granuloma⁴ or in the lymphoid system. Individuals with latent tuberculosis are asymptomatic and are not contagious. Latent TB is diagnosed by a blood test which has replaced the skin test done previously (PPD/Mantoux Test).
- Active Tuberculosis: Active tuberculosis occurs when the immune system is unable to contain the tuberculosis infection, resulting in an active disease. Unlike latent TB, individuals with active TB experience symptoms like cough, fever, weight loss etc, and are capable of transmitting the disease to others. This stage requires prompt medical treatment and often develops after a period of latent tuberculosis, although it can also occur directly in some cases.
Symptoms of Tuberculosis
The general symptoms that accompany a pulmonary tuberculosis infection include:
- Persistent cough
- Coughing up blood or sputum
- Fatigue
- Shortness of breath
- Chills
- Fever
- Night sweats
- Chest pain
- Loss of appetite
- Weight loss
- Malaise
It is important to note that the symptoms of tuberculosis often depend on the organ or system affected. As such, individuals with extrapulmonary TB may experience symptoms specific to the affected area. For example, someone with TB meningitis might present with headaches, sensitivity to light and other neurological signs.
History of Tuberculosis
Tuberculosis was discovered more than a century ago, on 24 March 1882⁵, by Dr Robert Koch. However, it is estimated that the disease has existed for over 3 million years. One of the earliest, undisputed evidence of TB is linked to bison in Wyoming, which lived over 17,000 years ago⁵. Tuberculosis doesn’t exclusively infect humans, but also affects animals, particularly mammals such as sheep, goats, pigs, cats and dogs.
Throughout history, tuberculosis has been known by various names, including “phthisis” in Ancient Greece, “consumption” in Europe and North America, and the “white plague” in the 1700s due to the extreme pallor it caused in patients. Koch’s groundbreaking discovery of Mycobacterium tuberculosis was a monumental step forward in understanding the contagious disease, laying the foundation for efforts to develop effective treatments.
From the 17th to 19th century, TB reached epidemic levels in Europe, causing nearly one in four deaths⁶. This alarming mortality rate spurred medical research, eventually leading to the development of the Bacille Calmette-Guérin (BCG) vaccine administered in 1921, which became widely used to prevent TB. The introduction of streptomycin in 1944, followed by other antibiotics, revolutionised TB treatment and significantly reduced fatalities.
Despite these advancements, tuberculosis remains a major global health concern, with millions of new cases reported each year, particularly in developing countries, further compounded by the rise of drug-resistant tuberculosis strains that continue to pose a serious threat. Efforts to combat TB are ongoing, with a focus on improving prevention, diagnosis and treatment to slowly and steadily eliminate the disease.
Global Prevalence of Tuberculosis
Tuberculosis claims over 1.3 million lives worldwide each year⁷, making it the world’s deadliest infectious disease. Although it was temporarily surpassed by COVID-19 in global mortality, the illness recently reclaimed its position with approximately 8.2 million people diagnosed in 2023⁸—the highest number recorded since monitoring began in 1995.
Despite its staggering death toll, TB is often regarded as a forgotten disease, largely because it rarely makes headlines. However, it disproportionately affects populations in high-burden countries, with India, Indonesia, China, the Philippines, and Pakistan accounting for 56% of the global TB burden⁸. This disparity is mainly due to TB thriving in countries with “low socioeconomic conditions”, where poverty, overcrowding and limited access to healthcare facilitate its spread.
Challenges in Controlling Tuberculosis
Highlighted below are some common challenges in trying to control tuberculosis worldwide:
- Drug Resistance: Certain strains of TB have developed drug resistance, making treatment more difficult. This can occur when the bacteria adapt to existing antibiotics or when medication is not taken correctly. The World Health Organisation (WHO)⁸ considers multidrug-resistant TB a public health crisis.
- Risk Factors: Immunocompromised individuals, such as those with HIV, patients on long-term steroid therapy, individuals with chronic medical conditions, and the elderly, are more vulnerable, making TB harder to control. Smoking and alcohol abuse are also risk factors for tuberculosis.
- International Travel: The impact of international travel and migration facilitates the spread of TB across borders, contributing to its global reach.
- Healthcare Gaps: Developing countries, which are often high-burden TB regions, frequently face limited resources in terms of diagnosis and treatment, making it challenging to control the spread of the disease.
- Global Attention: There is a lack of global awareness and action, particularly in countries where the necessary technologies and drugs to combat TB are available. This limits the international response to the disease.
- Insufficient Funding: Low- and middle-income countries which bear 98% of the global TB burden⁸ face severe funding shortages, hindering efforts to eradicate TB.
Efforts to Combat Tuberculosis
A multifaceted, global and coordinated response is needed to combat tuberculosis. While significant progress has been achieved in the development of vaccines, antibiotics and diagnostic tools, it is apparent that challenges linger, especially in high-risk areas where poverty, overcrowding and limited access to healthcare are pervasive.
Increased funding, improved healthcare infrastructure and international collaboration are necessary to address drug-resistant strains and ensure better access to treatment for all. In addition, public health initiatives, awareness campaigns, and ongoing research are key to advancing TB control efforts, aiming for the eventual eradication of this deadly disease. The WHO’s End TB Strategy, for instance, plays a pivotal role in these efforts, aiming to reduce TB deaths by 90%, cut new cases by 80%, and ensure that no family is burdened with catastrophic costs due to TB by 2030⁹. Still, the road to eliminating TB is long, and continued vigilance is required to make meaningful progress in the fight against tuberculosis.
If you would like to find out more about TB, contact our infectious disease specialists who can help and are willing to share more about the diagnosis, treatment options and prevention strategies today. Alternatively, visit our page here to learn more about the disease, as well as relevant information available to help combat tuberculosis.
References
- Global Tuberculosis Programme, Social Determinants. World Health Organization. https://www.who.int/teams/global-tuberculosis-programme/populations-comorbidities/social-determinants. Accessed 19 November 2024.
- TB Risk and People Born in or Who Travel to Places Where TB is Common. CDC. https://www.cdc.gov/tb/risk-factors/country.html. Accessed 19 November 2024.
- Extrapulmonary TB. TB Online. https://www.tbonline.info/posts/2016/3/31/extrapulmonary-tb/. Accessed 19 November 2024.
- Clinical Overview of Latent Tuberculosis Infection. CDC. https://www.cdc.gov/tb/hcp/clinical-overview/latent-tuberculosis-infection.html. Accessed 19 November 2024.
- History of world TB day. CDC. https://www.cdc.gov/tb/worldtbday/history.htm. Accessed 19 November 2024.
- Glaziou P, Floyd K, Raviglione M. Trends in tuberculosis in the UK. Thorax. 2018;73(8):702-703. doi:https://doi.org/10.1136/thoraxjnl-2018-211537. Accessed 19 November 2024.
- TB Is the Deadliest Infectious Disease. So Why Haven’t You Heard of It? Partners In Health. https://www.pih.org/article/tb-deadliest-infectious-disease-so-why-havent-you-heard-it. Accessed 19 November 2024.
- Tuberculosis resurges as top infectious disease killer. WHO. https://www.who.int/news/item/29-10-2024-tuberculosis-resurges-as-top-infectious-disease-killer. Accessed 19 November 2024.
- The End TB Strategy. World Health Organization. https://www.who.int/teams/global-tuberculosis-programme/the-end-tb-strategy. Accessed 19 November 2024.