To wear or not to wear a Mask??

A recent 2024 tuberculosis report find increase in cases as compared to previous year.

In 2024 tuberculosis report 27.8 lakh cases were reported in India which is slightly increased from previous year.¹ The incidence is usually estimated in adults since in children its paucibacillary leading to under-reporting of cases and difficulty in estimating the tuberculosis burden. The trends in India and globally show that children contribute about 5.7% and 3% of the total burden of drug sensitive and drug resistant tuberculosis.²

To diagnose tuberculosis in children is a challenge due to varied spectrum of symptoms, often non-specific, paucibacillary nature and more of extra pulmonary form of tuberculosis seen in them. The current diagnostic methods are sensitive and specific for rapid detection of tuberculosis in children. However, the low bacilli load still makes it difficult to diagnose the disease leading to rely on clinical parameters and history of contact with tuberculosis patient.

Many new modalities are being developed to overcome the shortcomings of the current methods. The C-Tb skin test is an advancement to tuberculosis skin test (TST) which in future may replace TST to screen for tuberculosis infection as it does not cross react with BCG vaccinated children. In radiology advancements are seen in reading chest X-rays and CT scans using the Computer Assisted Detection (CAD) software applications using artificial intelligence has increased the sensitivity and specificity of the imaging modality. They are able to distinguish bacterial pneumonia and tuberculosis which is often misdiagnosed. Other modalities like ultrasonography and MRI scan is also helpful in tuberculosis diagnosis.

The development of GeneXpert ultra has also helped in diagnosis of Tb as it can detect as low as 16 CFU/ml in specimen. Culture still remains the gold standard for diagnosis, but it takes 3-6 weeks for the final report to come.

Many samples are used for diagnosis of Tb ranging from sputum to nasopharyngeal aspirate, bronchoalveolar lavage and stool. In children usually it is difficult to obtain sputum as they often ingest the cough than expectorate it. Due to this gastric lavage is the preferred sample in children over sputum. Gastric lavage is invasive and discomforting for children due to which many parents opt out of it and often the child goes undiagnosed. There is a need for acquiring samples from children which are less invasive, less discomforting and easier to obtain.

Recently Lubeck developed a method at the Research Center Borstel to detect M. tuberculosis DNA from respiratory masks in children.³ FFP2 mask filters the exhaled air and has been used in adults with success for diagnosis of tuberculosis. Based on this concept similar trial was done for children. Children with pulmonary tuberculosis were made to wear three modified FFP2 masks containing a strip of 3D-printed polyvinyl alcohol for half an hour. The strip was used to obtain samples from the exhaled air. The masks then were examined the automated and manual polymerase chain reaction and target molecular biological methods were applied to identify antibiotic resistance via detecting changes in the genetic material of the bacteria (target next generation sequencing). The sensitivity of this method is high and can detect up to 4 copies of the pathogenic genetic material. Although such great results were seen invitro but in none of the children face mask they could detect M. tuberculosis. This indicated that this method is not superior to other methods available at present though it has shown good results in adults and secondly children with pulmonary tuberculosis may not be generating enough aerosols through which bacteria could be transmitted and not to forget the paucibacillary nature of the disease in children.

Another aspect that needs to be explored and standardized is using stool sample for detection of tuberculosis in children. As children ingest the cough/sputum it can be excreted through stool. Many studies have shown positive results with stool where gastric lavage sample did not detect M. tuberculosis. This sampling method is easier and non-invasive and can become the first sample screened in children with suspected tuberculosis.

References:

1. India TB Report 2024, Challenges to Eliminating TB, India’s Progress in Eliminating TB.
2. Rodrigues C, Singhal T. What is new in the diagnosis of childhood tuberculosis? Indian J Pediatr. 2024. https://doi.org/10.1007/s12098-023-04992-0.
3. Lennard Meiwes, Irina Kontsevaya, Dumitru Chesov, Stela Kulciţkaia, Viola Dreyer, Doris Hillemann, Qiniso Dlamini, Caroline Williams, Michael Barer, Folke Brinkmann, Renate Krüger, Stephanie Thee, Alexander Kay, Anna Maria Mandalakas, Christoph Lange, Whispers in the Wind: Face Mask Sampling for Mycobacterium tuberculosis Detection in Children With Pulmonary Tuberculosis, The Journal of Infectious Diseases, 2024;, jiae282, https://doi.org/10.1093/infdis/jiae282