About 10 million people contract and more than one million die each year from tuberculosis, most in countries far from the rich West. But yesterday’s World Tuberculosis Day serves as a reminder that this highly curable disease is a global problem – which is getting worse. The Covid-19 pandemic shows that infectious diseases do not respect borders, and TB remains a stubborn feature of Western cities, not just developing countries. With 150 cases per 100,000 people, parts of London in the recent past had higher TB rates than Iraq or Rwanda, areas of New York like Sunset Park or West Queens in 2019 were six times higher than the national average, and French experts last years, they were again worried about “hot spots” in northern Paris.
Three things solve this problem. Before it becomes active and contagious, usually attacking the lungs, TB can rest for years. Experts estimate that approximately one in four people alive today – approximately two billion – carry latent TB and about 10 percent of them will develop active TB during their lifetime. This means that the 10 million people who develop active TB each year are just the tip of the iceberg. The world has many people who tolerate active TB – and it is teeming with latent TB cases that are constantly becoming contagious.
Another problem is that Covid-19 made us look away from the ball. As the world concentrated on testing and searching for the SARS-CoV-2 pathogen, testing and searching for TB declined sharply. Deaths from this bacterial disease dropped from 1.7 million in 2000 to 1.2 million in 2019. But our recent neglect means that the number of TBs is expected to increase again. The partnership of governmental and non-governmental groups Stop TB estimates that we could easily face an additional 1.4 million deaths and 6.3 million active cases in the next five years. It is safe to assume that the number of additional, new latent TB cases is many times higher.
Third, we have to fight this expanded reservoir of latent TB just at the moment when the world is airing again after various waves of locking caused by Covid-19. People around the world will travel again and gather to study, do business or enjoy socializing again. As the world begins to boom again, millions of people will develop active TB after months or years of carrying a latent disease undetected in their bodies. Their symptoms can be mild and go undiagnosed and untreated for months. The World Health Organization (WHO) estimates that such patients can infect 10-15 other people over the course of a year.
The combination of these factors means that 1,500 Stop TB partnership organizations fear that the fight against TB could be withdrawn in five to eight years. WHO governments want to reduce annual TB deaths by 90 percent from 2015 levels, and annual new cases by 80 percent by 2035 – by screening for latent TB and preventing cases from becoming active, testing and treating active cases and seeking contacts. If the Stop TB warnings prove correct, its decisive actions in recent years will be reversed.
Fortunately, the main work of the WHO, Stop TB and their partners, working under the auspices of the United Nations, means that this worst case scenario is not a deliberate conclusion. The world can redouble its anti-TB measures to identify and treat people with TB and rapidly reduce the recently increased fund of undiagnosed cases. This would require a strong return to checking and treating latent cases, as well as intensified testing for active cases along with community engagement and contact seeking. This means that we must ensure that as many latent and active TB patients as possible get access to the right treatment as soon as possible.
Ironically, there are two legacies of our response to Covid-19 that should give us hope for TB. Many healthcare systems now have unprecedentedly large testing and monitoring infrastructures that we can use to test for TB. Equally, ordinary people around the world have understood, supported, and even passed disease tests over the past year. This “test mindset” allows governments to create an unprecedented momentum to test campaigns against latent TB. TB is one of the oldest infectious diseases whose traces were found in the mummies of the ancient Egyptian pharaohs. It has haunted humanity for millennia. We still have a chance to finally put it under control.
Photo: ThitareeSarmkasat, Getty Images