Childhood tuberculosis: addressing a forgotten crisis
Of the 9 million estimated cases of tuberculosis (TB) each year, at least 10 to 15 percent occur in children. Yet the problem is dangerously neglected, because most diagnostic tests are not designed for children.
The magnitude of this neglected public health problem is highlighted in a letter published in the New England Journal of Medicine this week by a TDR-led group of experts on paediatric TB. The team has joined forces with the Stop TB Partnership's Childhood TB subgroup, the World Health Organization's Stop TB Department and other international experts on paediatric TB to promote the adoption of a common reference standard for the evaluation of new TB diagnostics in children.
While new breakthrough diagnostic tests for TB are being developed, including one endorsed by WHO in December, the advances highlight a significant gap in TB research generally: the paucity of diagnostic research and of reliable diagnostic tools for TB in children. Historically, children have received a lower priority than adults in TB control efforts because they are both considered less infectious and are more difficult to diagnose.
Because their symptoms are different to the classic chronic cough of TB in adults, children usually go to a children's health service or a general clinic rather than a TB diagnostic centre. The result is that many cases go undiagnosed or are diagnosed incorrectly, so that children are more likely to rapidly progress to a severe state such as TB meningitis, which has harmful long term effects and high mortality.
"Our ability to even assess the magnitude of the problem is severely hampered by the lack of diagnostics in children," said Dr. Luis Cuevas, a scientist from TDR's diagnostics team. The problem is that TB diagnostic tools, both currently and in development, do not adequately take into account the special requirements for assessing children, he said. Cuevas is the author of a recent paper focusing on the problem.
"While there are a lot of promising diagnostic tools in the works, there is a need for increased support from international organizations and funders to promote the development of new diagnostics that are suitable for TB in children," said Cuevas. The common reference standard being prepared by the team of paediatric TB experts provides guidelines for paediatric testing of new diagnostic tools, specimen sampling methods, and comparative testing in different country settings. Further work to develop standardized methods to evaluate new TB diagnostics in children is currently under way.
The authors of the original NEJM article, Boehme et al., replied that they "can only agree that additional studies in children are a priority."
TDR's coordinator for research on neglected priorities, Soumya Swaminathan, is guest editor of a special issue on TB in children for The Indian Journal of Paediatrics. Next March, a conference will be held in Stockholm to advocate for research on paediatric TB, which will be organized by the European Centre for Disease Prevention and Control together with the Stop TB Partnership. In June, the U.S. National Institutes of Health will hold a meeting to set a standard method for evaluating and defining priorities for research in TB diagnostics for children.
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