Can repurposing masks to detect child TB work?

Researchers from the Foundation for Medical Research, based in Mumbai, were studying the use of masks to detect the presence of TB bacteria in adult patients when they saw a potential for the masks to be used for children, too.

The masks were fitted with a gelatin-like membrane that captures respiratory particles expelled by the child through talking, coughing, or taking deep breaths. The membranes were then taken to check the presence of TB bacteria, which, if found, usually indicate an active TB infection, Kalpana Sriraman, researcher at FMR, told Devex.

Through the mask sample, researchers were able to detect TB in 9 out of the 10 children involved in the pilot. However, they were only able to do so with the use of polymerase chain reaction, or PCR, test. The GeneXpert test was only able to detect TB in 1 out of the 10 children, showing initial limitations of the method.

India’s Central TB Division has expressed interest in the study results, said Dr. Nerges Mistry, director at FMR and the study’s principal investigator, but the researchers intend to conduct further studies involving a larger number of children.

A study published early this year in The Lancet by researchers from the University of Leicester and the University of Pretoria have also identified the potential of mask sampling in TB detection. But the India study was the first to try it on children, Mistry said.

Diagnosing TB in children remains a challenge and requires more innovation, experts told Devex. Current methods are cumbersome, require particular health systems capacities and expertise — which can differ across countries and within countries — and can lead to underdiagnosis. In addition to tests, clinical acumen and a child’s history of contact with someone with TB also plays a role in pediatric TB diagnosis, said Dr. Suvanand Sahu, deputy executive director at the Stop TB Partnership.

The most common method for childhood TB detection is through sputum sampling. But children find difficulty in producing sputum, and are often subjected to invasive, stressful methods like gastric aspiration, a procedure in which a tube is inserted into the child’s nose to reach the stomach. Noninvasive methods such as stool sampling have gained interest in recent years, but processing the sample can be challenging, said FMR’s Sriraman.

The World Health Organization currently recommends the use of Xpert MTB/RIF assay for stool samples for pediatric TB.

“There are many limitations in bacteriologically confirming TB in children. It's problematic because a lot of times now with the rise in drug-resistant TB, just clinical diagnosis can miss drug-resistant TB and it can lead to more protracted treatments, incomplete treatments or ... incorrect treatment,” said Dr. Farhana Amanullah, chair of the Stop TB Partnership’s Working Group on Child and Adolescent TB.

Chest X-rays are used in pediatric TB detection, but this method can run into issues of quality and require experts such as radiologists to interpret. The tuberculin skin test and the interferon-gamma release assay blood test help determine if a patient is infected with TB, but other additional tests will be needed to determine whether the patient has latent TB infection or active TB disease.

The TB community has long raised the issue of limited investments in TB research and development. TB treatment continues to be burdensome for both patients and health workers, and there remains only one licensed vaccine for TB, which is already 100 years old. But experts note that TB innovations are even further behind for children.

With TB in children found to be less infectious than those in adults, there’ve been fewer investments in childhood TB R&D, including for diagnostics.

“It's often believed that they [children] don't transmit the disease as much. So I think because of [the] lack of transmission threat, child TB has been left fairly under-researched,” said FMR’s Mistry.

But missing children with TB has disastrous consequences. WHO estimates over 200,000 children die from TB every year, and a large percentage of these deaths are undiagnosed and therefore untreated. The U.N. high-level meeting for TB targets 3.5 million children treated for TB by 2022. But as of 2019, only 1.04 million — 30% of the target — were treated.

The burden of childhood TB was not measured until the WHO global TB report in 2012. But estimates of TB-disease burden in children to date remains challenging.

“Symptomatically their symptoms resemble other common childhood illnesses. So if a child comes in looking like they have a lower respiratory tract infection, or pneumonia, they will get treated as pneumonia, and perhaps maybe get a little bit better. But they might have TB, and if they're not treated quickly enough, they may die of the condition,” Amanullah said.

Source: Devex