Combatting TB 2.0

By Jose Luis Castro
March 24, 2014

Earlier this month, health officials in Los Angeles confirmed they are treating a patient for extensively drug resistant tuberculosis — a deadly form that does not respond to most of the antibiotics. The United States is one of 100 countries that have reported cases of “XDR-TB” since it was discovered in South Africa less than a decade ago.

Congress is holding public briefings Tuesday and Wednesday to look into the threat posed by tuberculosis, seeking expert recommendations to help develop a U.S. response. To be effective, public health efforts must adapt to the ways TB is evolving.

Tuberculosis is often described as an “ancient” malady, evident in Egyptian mummies. But today’s tuberculosis epidemic, which kills around 1.3 million people a year, is unlike its predecessors genetically, clinically and epidemiologically. Defeating TB 2.0 will require innovative approaches designed to fight this modern epidemic.

Many of the TB strains today come from “modern” genetic lineages rather than the “ancestral” strains common throughout human history. Modern TB strains now predominate in India, which has the world’s highest TB burden, according to recent research published in the International Journal of Tuberculosis and Lung Disease. Some modern strains are more virulent and progress more rapidly, studies suggest, making the disease far more dangerous.

Clinically, today’s TB is “partnering” with a number of modern diseases, creating complex illnesses that are more challenging to treat. While TB has historically been perceived as a lung disease, in people with HIV it often presents elsewhere — lymph nodes, spine, eyeballs, brain — with atypical symptoms. TB kills roughly 320,000 HIV-positive people every year, the leading cause of death for those HIV positive. Yet less than half of the people infected with HIV have been screened for TB, and vice versa.

Adults with diabetes are also more vulnerable to TB and tend to have worse treatment outcomes. Since 1980, the number of people living with diabetes has more than doubled worldwide, to around 350 million. Three-quarters of diabetics now live in the developing world. With new evidence showing that diabetes is fuelling TB, the governments of China and India have instituted policies and programs to address both diseases simultaneously. But in most other countries, TB patients are rarely screened for diabetes, nor diabetics screened for TB.

Smoking is also adding to this lethal brew. Tobacco companies are increasingly shifting their operations into developing countries, where people commonly live with latent TB infections. Normally these infections stay dormant, posing no harm — one-third of the world’s population lives with one. But smoking tobacco increases the risk that a latent TB infection will progress to the full-blown disease, which can kill and spread to others. In addition, new research published this week  shows that regular tobacco use doubles the risk that a person cured of TB will develop the disease again. This “recurrent” TB is more likely to be drug resistant and is typically more complex and costly to treat.

Looking to the future, population movements will increasingly contribute to a resurgence of TB. One-third of the world’s population lived in urban areas in 1976. Today half does, and that proportion is predicted to rise to two-thirds by 2050. By 2030, the United Nations predicts that around two billion people will be living in slums, where overcrowding and poor ventilation provide the ideal environment for spreading TB.

Medicine alone cannot stop it. The fight against this new TB requires new approaches to architecture and urban design that promote air flow and reduce the risk of disease transmission. The need is especially urgent with regard to hospitals, prisons, schools, homeless shelters and nursing homes — all potential breeding grounds for TB.

The advent of “TB 2.0” has already set off alarm bells. The British government is now considering adding drug resistance to the National Risk Register, which catalogues the most serious threats facing the nation. Britain’s chief medical officer, Dame Sally Davies, has cited multi-drug resistant TB as a major peril.

Partners are crucial here. The Bill & Melinda Gates Foundation, for example, has invested billions of dollars to fight TB and other diseases. It is helping call attention to the bacteria’s ability to evolve — which requires new technologies and approaches to thwart it.

It’s time we stop thinking about TB as an “ancient” disease. That mindset leaves us open to the twin pitfalls of complacency and resignation — complacency that the same old approaches will continue working as before, and resignation that TB is somehow unbeatable and destined to afflict humanity forever.

Neither statement is true. And millions of lives hang in the balance.

 

PHOTO (TOP): Clinical lead Doctor Al Story points to an x-ray showing a pair of lungs infected with tuberculosis during an interview with Reuters on board the mobile X-ray unit screening for TB in Ladbroke Grove in London, January 27, 2014. REUTERS/Luke MacGregor

PHOTO (INSERT 1): A lab assistant performs an experiment during an inauguration visit of a new P3 level research laboratory against tuberculosis at the School of Life Sciences of the Swiss Federal Institute of Technology (EPFL) in Ecublens near Lausanne, March 17, 2010. REUTERS/Denis Balibouse

PHOTO (INSERT 2): Doctor Marion Aritonang (R) speaks about tuberculosis in front of newly diagnosed tuberculosis patients at the Indonesian Union Against Tuberculosis clinic in Jakarta, April 4, 2011. REUTERS/Beawiharta

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