BackChildhood TB cases higher than WHO estimate; India has highest burden: study
Lancet estimates that over 6,50,000 children develop TB every year in the 22 countries with a high burden of the disease, including India
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Mumbai: Almost 25% more children fall sick with tuberculosis (TB) every year than the World Health Organization (WHO) estimates that most anti-TB programmes worldwide rely on, according to a new research report published in The Lancet Global Health.
Lancet estimates that over 650,000 children develop TB every year in the 22 countries with a high burden of the disease, including India. A 2012 study by WHO estimated the number at 530,000.
India had by far the highest burden of childhood TB, accounting for 27% of the total burden in these countries.
The new findings show that about 7.6 million children younger than 15 years in the 22 high burden countries became infected with Mycobacterium tuberculosis in 2010. Of these, roughly 650,000 developed TB. The overall estimated case detection rate was 35%—meaning that 65% of active TB cases in children are missed every year by national TB programmes. This case detection rate is substantially lower than the WHO estimate of 66% in adults, the Lancet report highlighted.
The report also suggests that about 15 million children are exposed to TB every year, and roughly 53 million are living with latent TB infection, which can progress to infectious active TB at any time.
These findings highlight an enormous opportunity for preventive antibiotic treatment among the 15 million children younger than 15 years who are living in the same household as an adult with infectious TB, said Peter Dodd from the University of Sheffield, UK, and lead author of the Lancet article.
“Wider use of isoniazid (a key antibiotic used in TB treatment) therapy for children as a preventative measure would probably substantially reduce the numbers of children who go on to develop the disease," he said.
According to Dodd, children are an often ignored but important part of TB control efforts. “In high-burden settings, childhood TB makes up a substantial fraction of the total TB burden. The estimated incidence is higher than the number of notifications, with under-reporting more common in younger children."
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, the report said.
“These findings show that what often has been taken as truth—that control of tuberculosis in adults will inevitably result in improved tuberculosis control for children—is fallacious as a stand-alone control strategy," Dodd added.
Until the gap in case-detection and reporting is closed, children will continue to suffer from insufficient access to appropriate resources. The crucial role of childhood infection as a reservoir for future disease cases is ignored in many high-burden countries.
“Without improved case-detection and prevention strategies for children, it is difficult to envisage the high-burden countries following the same downward trajectory of incidence rates seen by industrialized countries during the past several decades," says Andrea T. Cruz and Jeffrey R. Starke from the Baylor College of Medicine, Houston, US, who were cited in the Lancet report.
Instead of relying on paediatric case reporting, the researchers took a complementary approach, using mathematical modelling to estimate rates of infection and disease in children, based on country-specific data on household and population structure, and the prevalence of TB in adults. The model incorporated both social and epidemiological variables including the effects of age, BCG vaccination efficacy, and the effect of HIV infection.
Apart from India, other high-burden countries that account for 80% of TB cases worldwide include Afghanistan, Bangladesh, Brazil, Cambodia, China, Congo, Ethiopia, Indonesia, Kenya, Mozambique, Myanmar, Nigeria, Pakistan, the Philippines, Russia, South Africa, Thailand, Uganda, Tanzania, Vietnam and Zimbabwe.
Tuberculosis remains a major global health problem, says WHO. According to its Global Tuberculosis Report 2013, an estimated 8.6 million people developed TB in 2012, and 1.3 million died from the disease. “The number of TB deaths is unacceptably large given that most are preventable," the WHO report had said.
The WHO report had however cautioned that although the level of active TB disease had fallen by 37% globally since 1990, the target of a 50% reduction by 2015 is not expected to be achieved.
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