Five years ago, both the World Health Organization (WHO) and United Nations committed to ending tuberculosis by 2035. Today their focus has shifted considerably toward a different infectious disease. The inability to eradicate tuberculosis amid a formidable array of medical and public health resources serves as a cautionary tale for other endemic diseases such as influenza and Covid-19. However, just as our unfinished quest to eradicate tuberculosis should inform our expectations around the current pandemic, the reverse is also true. Valuable lessons have emerged in the past year that we can use to improve efforts to contain not just tuberculosis, but other infectious diseases.
Tuberculosis is still the leading cause of death from an infectious disease in adults around the world, with more than 10 million people being infected and around 1.4 million people dying each year. Although global health efforts have saved an estimated 63 million lives from tuberculosis since 2000, the annual rate of infection and mortality reduction appears to be insufficient. Not to mention Covid-19, its lockdowns, and the increasing amount of healthcare resources being directed away from tuberculosis and towards the pandemic has only made the situation worse.
Tuberculosis diagnosis is often delayed due to passive case finding, which requires infected individuals to be aware of their symptoms and to have access to health facilities. It is also troublesome as biological sampling can be non-representative, and conventional diagnostic methods aren’t always accurate. About half of tuberculosis cases are detected by smear microscopy, which requires culturing the organism for as many as 6 weeks.
Treatment distribution is still an obstacle to ending tuberculosis. Two new tuberculosis therapies, Sirutro and Deltyba, deliver cure rates of up to 80%, which is significantly higher than older treatments. However, prices have become a flashpoint because the drugs are often used in conjunction with other therapies, raising the overall care costs even higher. The prices were so high, that the Indian government had to rely on donations from the Stop TB Partnership’s Global Drug Facility, a non-profit. Since patents on these drugs prohibit alternative manufacturers from providing lower-cost generic versions, and since these patents do not expire until 2023, there is simply not enough of the drugs available in India today to meet the huge public health need. As a result, health-care providers are rationing or even refusing to prescribe the medications for fear of running out.
Compared to 2019, in 2020 14 million fewer tuberculosis patients received treatment and 500,000 more deaths occurred, bringing mortality rates close to 2010 levels. In 2019, there were an estimated 3 million active tuberculosis cases that had not been diagnosed. Given the shift in global health priorities, it can be assumed that even more went undetected last year. The WHO’s 2020 guidelines include a renewed emphasis on systematic screening to close the diagnosis-to-care gap. In high-prevalence areas, expanded community screening could help reduce the burden of latent tuberculosis infection. It may be more beneficial to conduct aggressive case finding within higher-risk groups, such as household contacts, HIV-positive people, and incarcerated people.
Tuberculosis is a disease of poverty and disadvantage, with wide disparities among and within populations. Marginalized communities, such as indigenous peoples, refugees, and the homeless, are frequently the ones that suffer the most. In most countries, incarcerated populations have a significantly higher risk of tuberculosis infection than the general population. This risk highlights the importance of maintaining health-care involvement while incarcerated and directing preventive assistance toward higher-risk populations, such as people living with HIV, as well as the need for better-designed facilities that can manage infection control.
While Covid-19 is not a disease of poverty and disadvantage, it does disproportionally affect certain classes. Incarcerated people were also among the worst hit during the Covid-19 pandemic, with rates as high as one in three people being infected inside US prisons. Uneven vaccine distribution has also been a cause for concern on a local and on a global scale, which tuberculosis has shown us to be an issue we could face long term. India is relying on donations to acquire a tuberculosis treatment which should be considered a global public good. Given the recent waiver India and South Africa obtained from the TRIPS Agreement regarding Covid-19 vaccines, countries should benefit from such an agreement for all lifesaving treatments.
The aim of eradicating tuberculosis in the next decade is optimistic, and the current pandemic has slowed progress, but Covid-19 has shown that political will and investment can lead to remarkable public health efforts and scientific developments in the fight against infectious disease. Both viruses have taught us valuable lessons regarding public health and medical care. Learning to build the bridge between the lessons learned from tuberculosis and those learned from Covid-19 will give us a rare chance to reinvigorate the battle against both.