WHO: Better surveillance reveals higher TB burden

Tuberculosis bacteria
Tuberculosis bacteria

Alpha feto-protein stain of Mycobacterium tuberculosis, which causes TB., iStock

An estimated 9 million people contracted tuberculosis (TB) globally in 2013, a number that is almost half a million higher than previous estimates, thanks to better surveillance, but the disease is continuing to decline overall, the World Health Organization (WHO) said in its annual TB report today.

The agency estimates that 1.5 million people died of TB last year, and 360,000 of them were HIV-positive. But the TB mortality rate has dropped 45% since 1990, and the number of people developing the disease is falling by an average of 1.5% per year.

Mario Raviglione, MD, director of the WHO's Global TB Programme, said spending on national TB surveys and routine surveillance has increased substantially. "This is providing us with much more and better data, bringing us closer and closer to understanding the true burden of tuberculosis," he said in a WHO press release.

Although the new estimate of annual cases is higher, it falls within the upper limit of previous WHO estimates, the agency said. But it said the annual death toll for a curable disease remains "staggering," and TB is the second worst killer disease caused by a single agent, after HIV.

Of the estimated 9 million people who developed TB last year, including 550,000 children, about 64% were reported as newly diagnosed cases, the report says. That leaves about 3 million cases that either were not diagnosed or were diagnosed but not reported to national TB programs.

The treatment success rate continued to be high in 2013—86% among all new cases, the WHO reported.

Half a million MDR-TB cases

The agency said multidrug-resistant TB (MDR-TB) remains a challenge, with an estimated 480,000 new cases in 2013. With more laboratories using rapid tests, the number of cases diagnosed has tripled since 2009. Last year it reached 136,000 cases, with 97,000 people started on treatment.

Karin Weyer, DSc, the WHO coordinator for laboratories, diagnostics, and drug resistance, said in the release, "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. 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."

The report also says that extensively drug-resistant TB, which is even harder to treat than MDR-TB, has been reported in 100 countries.

Along with the annual TB report, the WHO published a special supplement marking 20 years of surveillance on drug-resistant TB, with an outline of the response so far and priority actions going forward.

Concerning the linkage between TB and HIV, the WHO said an estimated 1.1 million (13%) of the 9 million people who fell ill with TB in 2013 were HIV-positive, with 4 out of 5 cases and deaths occurring in Africa. But the number of TB deaths among HIV-positive people dropped from 540,000 in 2004 to 360,000 last year.

In other observations, the report says:

  • The 2015 Millennium Development Goal of halting and reversing TB incidence has been achieved globally, in all six WHO regions, and in most of the 22 countries that account for 80% of the TB burden.
  • A shortage of funds is hampering efforts to combat the global epidemic. An estimated $8 billion is needed each year for a full response, but there is currently an annual shortfall of $2 billion.

See also:

Oct 22 WHO statement

Global TB Report 2014 homepage and executive summary

WHO TB fact sheet

WHO's "10 Facts about TB"

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