Twenty-five per cent more children are falling ill with tuberculosis than the UN had thought, with more than 650,000 hit by the disease each year in the 22 worst affected countries, specialists say.
Reporting in The Lancet on Wednesday, they said that about 53 million children under 15 are living with latent TB infection, a condition that can develop into active TB at any time.
A contagious disease of the lungs, TB is caused by a microbe called Mycobacterium tuberculosis. Millions of people are latent cases, meaning they are infected with the germ but have yet to develop any symptoms.
Last year the World Health Organisation (WHO) estimated there were 530,000 cases of active TB among children younger than 15 years in 2012.
But this estimate was based on reporting by pediatric doctors - a technique faulted by many experts as its methods and reliability vary hugely from country to country.
The new estimate is based on a mathematical model based on each of 22 countries where TB falls into the category of a "high burden" for health.
It factored in the national prevalence of TB in adults, the likely risk of household exposure from infected relatives and the effectiveness of vaccination against the disease.
The findings suggested that about 7.6 million children younger than 15 in these 22 countries became infected in 2010. Of these nearly 651,000 developed the disease, more than a quarter of them in India alone.
Lead author Peter Dodd of the University of Sheffield said the figures pointed to the urgent need to focus help on children, using the drug isoniazid.
"Children are an often ignored but important part of TB control efforts," Dodd said.
"Quantifying the burden of TB in children is important because without good numbers, there can be no targets for improvement, no monitoring of trends and there is a lack of evidence to encourage industry to invest in developing medicines or diagnostics that are more appropriate for children than those available today."