Twenty-five percent more children are falling ill with TB than the UN had thought, with more than 650,000 hit by the disease each year in the 22 worst affected countries, specialists said Wednesday.

Reporting in The Lancet, 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 yet 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 paediatric 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.

Dr Peter Dodd, told VoR: “The approach that we were making estimated figures in the region of 650,000 children developing TB. We were doing the study for the year 2010 and concentrating on the 22 highest-burdened countries which probably contain about 80 percent of the global burden of TB.

“People have only recently started to try and put together estimates of the burden of TB in children. The previous numbers from the World Health Organisation were based on occasions reported to them by countries, but very many countries don’t record the number of children who develop TB. And even where they do, that can be quite challenging because TC in children is often quite difficult to diagnose.

“TB is a very unusual infectious disease in that it can cause disease a very long time after the original infection. Most individuals – particularly adults – who get infected don’t go on to develop disease from TB. But if they do develop disease, they can develop it after 10 or 20 years.

“Children are a bit different. They might lead to develop disease soon after infection and the forms of disease they develop are often quite serious.”

(VoR, AFP)