The study’s findings were published in a special theme issue of Lancet marking World TB Day on Monday, and offer the clearest picture to date of the global burden of TB, and the first estimates of the new threat: MDR-TB, multidrug-resistant TB.
Helen Jenkins of Brigham and Women’s Division of Global Health Equity in Boston is the lead statistician on the study, published in Sunday’s Lancet. Her co-author, Dr. Ted Cohen, also from the Harvard-affiliated Brigham and Women’s Hospital, noted that there haven’t been previous estimates on how many children suffer from TB; until now, researchers have largely ignored TB infections among young children, at least partially because they are less likely to transmit the disease than adults.
TB is caused by bacteria that attack the lungs, and is often airborne spread when those with an active infection cough. The infections are especially difficult to diagnose in children because kids are much more likely to have TB in other parts of their body, not necessarily in the lungs. Jenkins says that children often have fewer TB pathogens present “making kids with TB invisible” to current diagnostic methods.
To estimate numbers, the research team scoured publically available databases and devised a formula to correct for chronic underreporting of childhood TB. They found earlier estimates of total childhood TB cases at about 500,000, but factoring in the underreporting raises that to 1 million children developing active TB every year.
The World Health Organization estimates 8.6 million people of all ages developed TB in 2012, and of those 1.3 million died. Another half a million became sick with the dangerous “superbug” strain, and WHO estimates that up to 2 million may be infected with MDR-TB by 2015.
