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1 Million Children Have TB

New estimate doubles old number, finds 32,000 with multidrug-resistant strains

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One million children suffer from tuberculosis annually. That’s twice the number previously thought to have TB and three times the number that are diagnosed every year. What’s more, researchers have also estimated that around 32,000 children suffer from multidrug-resistant tuberculosis (MDR-TB) each year.

The findings by researchers from Harvard Medical School and Brigham and Women’s Hospital were published in The Lancet on March 24.

TB is an infectious disease that typically affects the lungs and is spread from person to person through the air. According to the World Health Organization, patients in India, China, the Russian Federation and South Africa represent nearly 60 percent of the world’s MDR-TB diagnoses. Eastern European and Central Asian countries are hot spots for the disease, accounting for nearly one-third of new infections and two-thirds of previously treated TB infections. When left untreated or inadequately treated, the risk of spreading additional drug-resistant strains increases.

“Despite children comprising approximately one quarter of the world’s population, there have been no previous estimates of how many suffer from MDR-TB disease,” said Ted Cohen, HMS associate professor of medicine in Brigham and Women’s Division of Global Health Equity and co-senior author of this study. “Our estimate of the total number of new cases of childhood TB is twice that estimated by the WHO in 2011 and three times the number of child TB cases notified globally each year,” said Cohen, who is also associate professor in the Department of Epidemiology at Harvard School of Public Health.

“TB in a child is recognized as a sentinel event; it tells us about ongoing transmission and missed opportunities for prevention,” said Mercedes Becerra, associate professor of global health and social medicine at HMS and co-senior author of the study. “Improved estimates are essential so that we can begin to understand the unmet need for pediatric TB treatment.” 

In order to obtain these estimates the researchers used several sources of publicly available data and devised a new method to correct for the chronic under-diagnosis that occurs in children, using conventional TB tests which were designed for and work best on adults. The researchers used two models to estimate both the regional and global annual incidence of MDR-TB in children. Their findings indicate that around 1 million children developed TB disease in 2010 and of those, 32,000 had MDR-TB.

These findings underscore the urgent need for expanded investment in the global response to TB and MDR-TB in children. “Our findings demonstrate that there is a need for improved methods for collecting data on childhood TB.  A good starting place would be improved diagnostic methods for children and more systematic collection of information on how many children are suffering with this disease,” said Helen Jenkins, HMS instructor in Brigham and Women’s Division of Global Health Equity and lead statistician on the project.

The study was supported by the U.S. National Institutes of Health (U54GM088558, K01AI102944, R01AI097015), the Helmut Wolfgang Schumann Fellowship in Preventive Medicine at Harvard Medical School, the Norman E. Zinberg Fellowship at Harvard Medical School, and the Doris and Howard Hiatt Residency in Global Health Equity and Internal Medicine at the Brigham and Women’s Hospital.