Amsterdam institute for Immunology and Infectious Diseases

Over 80% of individuals affected with tuberculosis (TB), the world's deadliest infection, do not exhibit a persistent cough, contrary to common perception. TB primarily spreads through coughing and inhalation. A study conducted by Amsterdam UMC and the Amsterdam Institute for Global Health and Development (AIGHD) analyzed data from over 600,000 individuals in Africa and Asia. Results revealed that 82.8% of TB patients did not manifest a persistent cough, with 62.5% showing no coughing at all. This research was recently published in The Lancet Infectious Diseases, in this article Professor Cobelens provides insights into the findings.

"We were already aware of the significant disparity between the 10.6 million TB patients and the 7.6 million officially registered with health authorities in 2022," notes Professor Cobelens, Global Health professor at Amsterdam UMC and a senior fellow at AIGHD. "Our findings shed light on a potential explanation for the marginal decline in TB cases in Africa and Asia, despite extensive efforts in diagnosis and treatment. A persistent cough often triggers diagnosis, yet its absence in 80% of TB patients suggests either delayed or missed diagnoses, likely after TB transmission has occurred."

Abundance of bacteria

Researchers examined data from national TB monitoring systems in 12 countries, revealing that, besides the lack of a persistent cough, over a quarter of TB patients exhibited no symptoms at all, with these trends more prevalent among women. Notably, a quarter of TB patients without a persistent cough had considerable bacterial presence in their sputum, indicating high contagiousness.

X-ray screening

"Summarizing these findings underscores the need to reevaluate TB diagnosis methods," emphasizes Professor Cobelens. "Current approaches overlook numerous TB cases, especially in resource-limited settings. Hence, there is an imperative to shift focus towards X-ray screening and the development of affordable, user-friendly diagnostic tests."

Unfinished tasks

This collaborative study involved researchers from Asia, Africa, and the World Health Organization, including Makerere University in Uganda. Bruce Kirenga, Director of Makerere's Lung Institute and a university lecturer in pulmonary medicine, echoes Professor Cobelens' call for reassessment. "The scarcity of cough in most active TB cases demands urgent exploration of more objective screening methods. While X-rays offer a solution, research into alternative biomarkers is warranted."

Kirenga adds, "These findings also impact TB prevention strategies, emphasizing the importance of treating TB infection to avert its progression to full-blown disease. In this regard, a persistent cough remains the simplest screening tool, highlighting the need for further advancements."

Read the scientific publication in the Lancet Infectious Diseases here.