One million TB cases in children annually

One million children aged below 15 years are annually diseased with tuberculosis across the world, notes a study published a few days ago in The Lancet . The new estimates are twice the number of children thought to have tuberculosis in 2010 and thrice the number of children who were actually diagnosed that year. The study has also estimated the number of children who were diseased with multidrug-resistant TB (MDR-TB) — in 2010, the number stood at about 32,000.

But there is very high possibility that even the new estimates are way below the actual number of diseased children. “It is certainly possible that the true numbers of children with both TB and MDR-TB will turn out to be higher than what we have estimated,” noted Dr. Mercedes C. Becerra from the Division of Global Health Equity, Brigham and Women’s Hospital, Boston and the Corresponding author of the paper.  “We used two existing sources of information from WHO reports — smear-positive cases reported to WHO from some countries, as well as WHO incidence estimates for all countries.  If those numbers are underestimates of TB, then that underestimation will play through into our child disease estimates.”

In fact, the authors had taken into account the fact that TB notification is way off the mark, and applied an “adjustment that took into account how smear microscopy misses more children than adults.” She, however, notes: “But we did not try to adjust for how the quality of case notification data varies across countries.” Therefore, in the case of India, there is a greater possibility of even the revised numbers being a gross underestimation.

With a huge population below the age of 15 years, and the number of new TB cases being about 2.3 million a year in the case of India, there is greater likelihood of more children being missed out.

Even the not-so-accurate revised estimates by the authors highlight the gross failure of the TB control programme of individual countries to diagnose a vast majority of children with TB and MDR-TB every year.

More reliable estimates of drug-sensitive and drug-resistant TB are essential for several reasons, prioritising government’s efforts to diagnose and treat more children with TB being the most important one. The study used the data available in 97 studies accounting for over 8,000 children who had undergone drug-susceptibility testing. The data was used primarily to “establish the relationship between the proportion of treatment-naive adults with MDR-TB and the proportion of children with MDR-TB” and not to arrive at estimating the total number of those with TB.

The study found that in a specific setting, the risk of MDR-TB was “nearly identical” in both children and adults who were never treated before.

Published in The Hindu on March 27, 2014