Tuberculosis in the age of global travel

While tuberculosis (TB) is no longer a widespread epidemic in many developed countries, it has by no means disappeared. Increasing global mobility and the expanding use of immunosuppressive therapies are creating new conditions conducive to the resurgence of this infection, challenging long-held assumptions about who is at risk of TB, and why. As a result, reliable screening is essential to protect vulnerable patients and safeguard public health.

In this article, we speak with Dr. Giuseppe Togni, PhD, Scientific Director of Infectious Serology and Microbiology at Unilabs Coppet, Switzerland, about the critical role of diagnostic accuracy in screening for latent diseases such as tuberculosis.

Why TB remains a global health issue

The World Health Organization (WHO) ranks TB among the leading causes of death worldwide, particularly in regions with limited access to healthcare. Southeast Asia accounts for nearly half of global cases, followed by Sub-Saharan Africa, where HIV co-infection accelerates transmission.

While TB remains more common in low- and middle-income countries, Dr Togni notes that the infection continues to pose a risk even in highly developed nations. “We live in a globalised world where more people travel than ever before. Say, for example, you go to Asia or Africa for a beautiful vacation. You could return feeling healthy, yet unaware that you contracted TB while away and that it now lies dormant in your system. Years later, if you develop a chronic illness requiring immunosuppressive drugs, you could suddenly test positive for TB. TB isn’t just a disease of developing countries. It’s a disease of movement, of migration, and of modern medicine itself.”

This reality, he argues, underscores why testing remains essential, even in countries with strong healthcare systems.

Switzerland’s TB strategy

While Switzerland does not operate a blanket TB screening programme for all residents or visitors, targeted testing is carried out for specific high-risk groups. These include individuals undergoing immunosuppressive treatments, such as patients with autoimmune diseases, as well as those who are expected to begin certain therapies, including organ transplant recipients. In these cases, compromised immunity can cause a latent infection to become active.

Switzerland also screens migrants arriving from regions with high TB prevalence. For these groups, the process typically begins upon arrival or during initial medical assessments. Based on a questionnaire-based risk score, additional evaluations, such as a TB test, may be arranged. Special attention is given to children under the age of five, who have a significantly higher risk of developing active disease if they carry a latent infection.

Finally, screening is offered to people who have been in contact with someone diagnosed with active TB. The aim is simple: to identify latent infections early and prevent transmission before it begins.

Why precision in testing matters more than ever

The consequences of a false-negative TB result can be severe, particularly for immunocompromised patients. Dr Togni explains that missing a latent infection can delay or prevent prophylaxis, increasing the risk of reactivation under immunosuppression. “Even a small risk of false results can directly affect whether prophylaxis is started or withheld. Accurate screening is therefore not a technical luxury; it is a patient-safety imperative.”

To modernise TB diagnostics, Dr Togni established a strategic partnership between Unilabs and QIAGEN, a leading provider of Sample-to-Insight solutions, to advance infectious disease diagnostics across Europe. Through this collaboration, Unilabs offers the QuantiFERON-TB Gold (QFT) test, which identifies latent TB by analysing T-cell responses and incorporates robust internal controls, including baseline (nil) and mitogen checks, to distinguish true negatives from immune-suppressed responses. “Understanding the immunology behind these assays—particularly the distinct contributions of CD4⁺ and CD8⁺ T-cell activation—enables clinicians and laboratories to better interpret borderline or unexpected results in high-risk patients,” he says.

As global mobility and medical complexity continue to increase, Dr Togni emphasises that maintaining a commitment to high-precision TB diagnostics will be essential to preventing reactivation, guiding treatment decisions, and ultimately reducing the global burden of tuberculosis.