Tuberculosis toll greater than previously estimated, says WHO

Mycobacterium tuberculosis bacteria

Mycobacterium tuberculosis bacteria

Janice Carr/Centers for Disease Control and Prevention

The global toll of tuberculosis (TB) is larger than previously thought, with an estimated 9 million new cases and 1.5 million TB-related deaths in 2013, according to a survey released today by the World Health Organization (WHO). The number of new cases—400,000 more than were estimated a year ago—is a sobering reminder of the challenges posed by the second biggest killer among infectious diseases after HIV.

But the findings are also a sign of advances in fighting the disease, according to WHO’s latest annual Global Tuberculosis Report. The higher numbers reflect better data gathering around the world, rather than an actual surge in the disease, the report notes. Countries are boosting measures to diagnose and track TB, “providing us with much more and better data, bringing us closer and closer to understanding the true burden,” said Mario Raviglione, WHO’s director of the Global TB Programme in Geneva, Switzerland, in a statement.

The report comes as nations work to hit a 2015 deadline for meeting benchmarks to tame the disease, laid out in the United Nations' Millennium Development Goals. Some regions—the Americas and several Asian countries, including China—have already hit their targets. And there are other bright spots. The rate at which people came down with new cases of TB fell 1.5% each year worldwide between 2000 and 2013. The death rate also continues to drop—down 45% since 1990.

But the report underscores a fundamental failure to gain control of the disease, some experts say. “There has been some real progress, particularly in Asia, but the overall situation remains catastrophic,” writes Richard Chaisson, director of the Johns Hopkins Center for Tuberculosis Research in Baltimore, Maryland, in an e-mail to ScienceInsider. “Improvements in some countries are offset by disastrous situations in others, with MDR [multidrug-resistant] TB, HIV-related TB and continued high rates of missed diagnoses and deaths. The situation in Africa is particularly horrific, with TB killing more young people than any other cause.”

One prominent activist criticized WHO for issuing an overly upbeat report, saying claims of progress were overshadowed by huge gaps in detection and treatment and a lackluster performance in combating TB compared with global efforts to address HIV infections. “On the HIV side, we're doing stuff almost twice as fast in [reducing] deaths and multiple times as fast in incidence, even though TB is curable and HIV is not,” says Mark Harrington, executive director of the New York City–based Treatment Action Group, which lobbies for stronger efforts to address both HIV and TB.

He blamed a shortage of funding, and a lack of urgency among leaders in some countries, as chief reasons why TB efforts have lagged. Countries spent $6.2 billion on the disease in 2013 (not counting $2 billion in research for better detection and treatment). But that’s nearly $2 billion shy of what countries estimate they need to tackle the problem, according to WHO.

WHO—which tracks and coordinates campaigns against TB—noted there are daunting barriers to progress in some parts of the world. Of the estimated 9 million people with new cases of tuberculosis, roughly a third either weren’t diagnosed or the diagnosis wasn’t reported to national health officials, according to the new report.

Countries continue to struggle with TB resistance to first-line drugs. The number of people receiving treatment for MDR TB tripled over 4 years to 97,000 in 2013. But more than 39,000 people with this hard-to-treat illness were stuck on waiting lists for treatment. And another 164,000 people with MDR TB were estimated to have not been diagnosed or not alerted to their illness.

The emergence of new cases of MDR TB held steady at 3.5% of all new infections worldwide. But certain countries have stubborn pockets of resistant infections. In Russia, roughly 20% of new cases were estimated to be drug resistant. But fewer than 20% of those people were alerted to their illness, according to the WHO report. Less than half of the people in China thought to have the disease were notified. China, Russia, and India together account for roughly half of all drug-resistant cases.

Even when drug-resistant cases are found, all aren’t treated. “The gap between detecting and actually getting people started on treatment is widening and we urgently need increased commitment and funding to test and treat every case,” warned Karin Weyer, WHO’s coordinator for laboratories, diagnostics, and drug resistance, in a statement. “In countries such as Estonia and Latvia, where there is universal access to rapid diagnostics and treatment, the number of MDR-TB cases has fallen significantly. This shows what can be achieved.”

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