The worldwide burden of childhood tuberculosis is twice as large as once thought, according to a new study that estimates nearly 1 million children become sick with the disease every year.
TB is the second leading cause of death from infectious disease on the planet, but as many as two-thirds of new TB cases in children go undiagnosed each year according to the study, which was published in The Lancet today to coincide with World TB Day.
The findings also shed light on a dangerous new front in the fight against TB: the emergence of drug-resistant strains that are increasingly difficult to treat. Of all children suffering from TB in 2010, nearly 32,000 were thought to have a drug-resistant mutation of the disease known as MDR-TB, according to the study. The paper represents the first major estimate of MDR-TB in children. Until now, fewer than 700 cases of the disease had been reported in the scientific literature.
"TB in a child is recognized as a sentinel event. It tells us about ongoing transmission and missed opportunities for prevention," said Mercedes Becerra, one of the study's authors and an associate professor of global health and social medicine at Harvard Medical School. "Improved estimates are essential so that we can begin to understand the unmet need for pediatric TB treatment."
The findings underscore shortcomings with how children are tested, Becerra told FRONTLINE. In many countries, the most widely used TB test relies on analyzing a patient's sputum — that's the mucus-like substance that comes up from the lungs when you cough. But because TB is just as likely to appear in a child's brain or bones as it is in the lungs, analyzing sputum is often counterproductive. Even if the disease is pulmonary, children carry a smaller bacterial load, making their sputum harder to read under a microscope.
Such shortcomings are especially worrying, said Becerra, given the heightened risks faced by children with TB. "Once they're infected," she noted, "children progress much more quickly. If they're going to get sick, they get sick faster and they die faster than adults do."
In 2012, an estimated 8.6 million people developed TB and 1.3 million died from the disease, according to the most recent figures from the World Health Organization. The WHO estimates that about 530,000 children develop TB every year, but the study's authors used a different methodology to arrive at their total.
The current epicenter of the pandemic is Swaziland, home to highest rate of TB infection in the world. In tomorrow night's FRONTLINE investigation, TB Silent Killer, filmmaker Jezza Neumann travels there for an unforgettable portrait of lives forever changed by the disease.
Among the patients he meets is Nokubheka, who at just 12 years old has already lost her mother to TB. Soon after her mother's death, Nokubheka was diagnosed with a strain of MDR-TB herself. As she told FRONTLINE in the following scene TB Silent Killer, "I think anybody can have TB. It is not choosy."
The film follows Nokubheka through months of treatment at Swaziland's national TB hospital. Although treatment can be a grueling and sometimes risky process — daily injections, for example, can lead to hearing loss — the disease can be cured if detected early enough. However as The Lancet study warned, "Continued failure to detect and treat child cases of TB and MDR-TB will result in the unnecessary deaths of large numbers of children."