Around 2,39,000 children across the world died of tuberculosis in 2015, according to a recent study published in the The Lancet Global Health. The estimates of the study, conducted by a team of scientists in the US and UK, are similar to numbers given out by the World Health Organisation, which earlier said that 2,10,000 had children died of TB in 2015.
The scientists used a mathematical model using a case fatality-based approach. Dr Peter Dodd, who led the study, explained: “Case-fatality-based estimate means that we started with an estimate of the number of children who fall sick with TB in a given year and applied evidence on the chances that these children would die from their disease in order to arrive at an estimate of mortality.” This means that the scientists applied the case-fatality rate to the total estimate of children with TB in a given year to arrive at how many children will have died that year.
The study evaluated TB incidence in children across 217 countries.
Globally, tuberculosis is recognised as a key contributor to disease burden in children. WHO estimates that a million children get TB every year and TB in children contributes to 11% of all cases of the disease worldwide.
Despite this, there is no age-segregated data for tuberculosis in children and the tuberculosis is not counted as a separate cause of death in in official estimates for under-5 mortality.
In the study, Dr Dodd and colleagues calculate estimates for TB deaths in two categories: the first is children under five years and the second is children between five and 14 years of age.
Of the 2,39,000 deaths projected by Dr Dodd and his collaborators, a massive 80% – nearly two lakh – of these deaths occurred in children under five years. More than 75% occurred in South-East Asia and Africa, which are known to have a high TB incidence. The study projects that the average case-fatality rate for tuberculosis in children was about 24% worldwide.
Of the total, 17% (39,000) of paediatric tuberculosis deaths worldwide occurred in children who also had HIV infections. Children who had TB along with HIV infection from WHO Africa region contributed nearly 80% of the 39,000 deaths. According to the study, India was by a huge margin the top contributor to the TB deaths in children, with more than 60,000 deaths in 2015. Next was Nigeria, with more than 20, 000 deaths. The top ten contributors accounted for 71% of the total TB mortality in children.
Shockingly, the study says that more than 96% of tuberculosis deaths occurred in children who did not receive treatment for the disease.
Dr Madhukar Pai, Associate Director, McGill International TB Centre at the McGill University, Canada, said that Dodd and his colleagues had used a more sophisticated modeling approach to estimate the burden of paediatric TB and the TB mortality rate in children than previous studies. “The study estimates that TB causes nearly a quarter million deaths in children under 15 each year,” Pai said. “This is sad and the death toll is mostly preventable, since TB is a curable infection.”
Despite the more sophisticated approach, Dr Yogesh Jain of the Jan Swasthya Sahayog, Chattisgarh said that the study under-estimates TB deaths in children. He explains, “This is inference from a mathematical model that trusts a country’s reported TB incidence data, which itself is susceptible to under-reporting.”
Jain said that in using case-fatality rates the study does not account for the impact of high levels of undernutrition among TB patients in India. “So, at best, these large estimates are at least a minimum estimate of child TB mortality,” he said. “The real estimates would be more sobering.”
TB in children
According to WHO, detection of TB disease in children is often overlooked because it has non-specific symptoms and is difficult to diagnose. “‘Most countries do a poor job of detecting and notifying TB among children,” Pai said. “India is a good example. India’s national TB programme relies on sputum smears, but young children are not able to produce sputum and even when they do, the number of bacteria in sputum samples is too low for microscopy to pick up. Also, children tend to have extrapulmonary TB and smears rarely work in such cases.”
Jain said that addressing under-nutrition is key to fighting TB. “The battle against tuberculosis cannot be fought without preventing the occurrence of the disease by improving the nutrition status, at least of children, through pro-active programmes. In the absence of this, the TB incidence rates won’t come down.”