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Study: Childhood TB Rates Much Higher than Estimated

FILE - X-rays of a tuberculosis patient at A. G. Holley Hospital in Lantana, Florida.

FILE - X-rays of a tuberculosis patient at A. G. Holley Hospital in Lantana, Florida.

Children are getting sick with tuberculosis at a much higher rate than previously estimated, according to a new study.

The research also presents the first-ever estimate of new TB infections among children: nearly eight million in 2010.

It’s a huge burden but an enormous opportunity to prevent future illnesses, the authors say, because low-cost treatment can stop infection from becoming disease.

Best guess

Hard data are hard to come by, but the World Health Organization’s best guess was that around a half-million children worldwide developed tuberculosis in 2011.

The WHO calculated that figure based on cases reported to health authorities. But many cases go unreported. Plus, TB in children is notoriously hard to diagnose.

So the authors of the new study in the Lancet decided to take a different route.

Family ties

“The vast majority of children who get TB who are young get it from someone in their family,” said study co-author James Seddon, a pediatrician with Imperial College London.

So the researchers used mathematical models to calculate how many children were likely to live with a family member with tuberculosis in the 22 countries that account for 80 percent of the world’s TB. They then estimated how many of those children got infected, and how many got sick.

They came up with roughly 650,000 illnesses in those countries, more than the WHO’s estimate for the entire world.

Most experts recognize the WHO’s estimate is low, so Seddon said that was not a huge surprise.

However, the group also found that 15 million children were living with a person with TB and 7.6 million were newly infected. No one had done those estimates before and, he said, they were “much greater than I had anticipated.”

"Not a priority"

WHO recommends preventive therapy for children exposed to or infected with TB but not showing symptoms. However, in most countries with high TB rates, Seddon said, they don’t get it.

“Treating children who are asymptomatic and completely well is usually not a priority” in countries with limited resources and large numbers of sick patients who are actively spreading the disease, he said.

However, he added, “We would hope that these numbers do strengthen the argument for saying to national programs, ‘Look, you’ve got a lot of children in your country who are infected with TB. And if they’re not identified and given preventive treatment this is going to be a problem that is not going to go away in the future.'”

How big?

Childhood tuberculosis has not gotten as much attention as adult disease in part because experts did not know how big the problem was.

“When UNICEF or other organizations ask us, ‘Well, how many children become sick with tuberculosis every year?’ we end up sort of wringing our hands and saying, ‘Well, it’s very complicated,’” said infectious diseases doctor Jennifer Furin at Case Western Reserve University. She was not involved in the research.

“This paper is an incredible addition to the field because it tells us how many children we need to be screening and targeting for preventive measures each year so that they don’t go on to get sick,” she said.

And by preventing those future cases, “This will impact not just the health of children, but it will also greatly impact the health of adults as well, and contribute to stopping the chain of transmission that’s unabated in high-prevalence countries,” said Baylor College of Medicine pediatrician Jeffrey Starke, who co-wrote a comment accompanying the article.

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    Steve Baragona

    Steve Baragona is an award-winning multimedia journalist covering science, environment and health.

    He spent eight years in molecular biology and infectious disease research before deciding that writing about science was more fun than doing it. He graduated from the University of North Carolina at Chapel Hill with a master’s degree in journalism in 2002.