This infectious disease remains a global health concern, and Leeds Teaching Hospitals NHS Trust is playing a key role in both treatment and research to improve patient outcomes.
What is Tuberculosis?
Tuberculosis (TB) is an infectious disease caused by bacteria from the Mycobacterium tuberculosis complex. It primarily spreads through the air when a person with TB in their lungs coughs or sneezes, releasing bacteria that others can inhale.
While TB can affect different parts of the body, the most common form impacts the lungs, leading to symptoms such as:
- A persistent cough lasting more than three weeks.
- Blood in phlegm.
- Unexplained weight loss.
- Night sweats and fever.
- Decreased appetite.
- Swellings in the neck.
Why is TB a growing concern?
TB symptoms can often be mistaken for other respiratory illnesses, especially since the COVID-19 pandemic. This confusion can delay diagnosis and treatment, increasing the risk of the disease spreading. Some people develop TB symptoms soon after exposure, while in others, the infection remains dormant for years before becoming active—this is known as latent TB.
A global crisis
TB is far from a disease of the past. It remains a serious global health threat, and the fight against it is far from over. As Dr. Tereza Kasaeva, Director of the WHO Global Tuberculosis Programme, pointed out, “TB has probably returned to being the world’s leading infectious disease killer” (WHO TB Report 2024). This statement underscores the scale of the ongoing crisis.
In 2023, 4,855 cases of TB were reported in England—an 11% increase from the previous year. While this rise is concerning, the overall rate remains relatively low at 8.5 cases per 100,000 people, keeping England below the World Health Organization’s threshold for a high TB incidence country. In Leeds, 8 people per 100,000 are affected by TB, and the city has seen a promising success rate in treating those who are diagnosed.
However, certain regions are bearing the brunt of the burden. A large portion of global TB cases comes from countries such as India, Indonesia, China, the Philippines, Pakistan, Nigeria, Bangladesh, and the Democratic Republic of the Congo, which collectively account for over two-thirds of all TB cases. In fact, the WHO has set a goal for 2027 to ensure that 100% of new TB diagnoses are made with rapid testing, up from the current rate of just 48%.
The TB-DILI study: Improving treatment and safety
TB is typically treated with a combination of four medications, known as the 4-drug treatment. While most patients complete their course without complications, some experience drug-induced liver injury (DILI), which can be detected through blood tests or symptoms such as jaundice.
- 53–57% of DILI cases occur within the first two weeks of treatment.
- 75–88% of cases occur within the first eight weeks.
When liver injury occurs, TB treatment is paused to allow recovery. But once the liver stabilizes, doctors must decide how to safely reintroduce treatment.
To help answer this question, Leeds Teaching Hospital is participating in the TB-DILI study, led by the Nottingham Clinical Trials Unit at the University of Nottingham.
Exploring safer treatment approaches
Once a patient’s liver recovers, doctors typically follow one of two approaches:
- Restarting all four drugs and completing the standard six-month treatment.
- Omitting pyrazinamide, a drug linked to liver complications, and extending the treatment to nine months.
Early research suggests that leaving out pyrazinamide may reduce the risk of further liver damage, making it a safer and less disruptive option. The TB-DILI study aims to determine the best approach for both patient safety and NHS treatment protocols.
The TB-DILI study is also examining how latent TB cases can develop liver injuries and how to manage those situations effectively. Participants in the study are typically identified by doctors working at TB clinics.
Currently, 4 participants at Leeds Teaching Hospital NHS Trust have been recruited to the active cohort and 4 to the latent cohort of the study. You can read more about the study.