Analysis shows TB may be sixth highest cause of under-five deaths; toll could be prevented with improved case-finding, diagnosis
A study has produced the first estimates of the role of tuberculosis in the deaths of children under five years old, and estimates across age spans of children up to the age of 15 approaching four times the numbers estimated by the World Health Organization in 2012. The study, a mathematical modelling exercise drawing on estimated incidence rates among children, combined with the demonstrated impacts of known variables that include age, HIV infection, and treatment for HIV, found that about 239,000 children under the age of 15 died of tuberculosis in 2015, about 80 percent of them — about 191,000 — were children under five years old. About 39,000, or 17 percent, were children with HIV. About 96 percent of all of the children died without receiving treatment for the disease, with indications, according to the authors reporting the study in The Lancet, that most of these children went undiagnosed, as well as untreated.
This means that improved efforts to find children who have been exposed to tuberculosis, or are at high risk for the disease (see Science Speaks, August 9), as well as increased use of existing diagnostic tools (including the Xpert Ultra test released this year) that accurately detect the disease in children as well as the development of new tools that can be used with children, would significantly reduce deaths from the disease among children, particularly those younger than five, the authors note. Their calculations peg the impact of tuberculosis as the sixth leading killer of children who don’t reach their fifth birthday.
Lack of appropriate tools to diagnose the disease in children, as well as insufficient use of existing tools, are one of the reasons that estimates of the toll of tuberculosis on children have been missing and inaccurate the authors say. Children have difficulty summoning sufficient sputum for the most common and accessible test for tuberculosis. The disease in children also often takes up residence outside of the lungs, and with smaller amounts of bacteria that are difficult to measure. In addition, because the disease is often missed in children, and its symptoms may appear similar to those of other diseases that include pneumonia, death records, a source of data for the earlier estimates of TB mortality, can be, and often are, incomplete, the authors write.
In 2012, the World Health Organization estimated that as many as 64,000 children younger than 15 had died of tuberculosis in 2011. A few years later, in 2015, the agency estimated 136,000 children had died of the disease in 2014. Then, in 2016, revised data, based on more accurate numbers of new cases across all ages provided by countries, WHO estimated that 210,000 children under 15 had died of tuberculosis the year before. The agency had never produced an estimate of the impact of TB on children younger than five, although reducing under-five deaths is a major international sustainable development goal.
The study was led by Peter Dodd, of the University of Sheffield, who has led previous mathematical modelling studies estimating the impacts of the disease.