Diagnosing TB in children is no child's play

Diana Esther Wangari, CNS Special Correspondent
Photo credit: Rahul D/CNS
All of us have surely been witness to or personally experienced the sight of a kid throwing tantrums and wailing in a super market or a mall for that extra chocolate bar or candy. The child refuses to pay heed to the protestations/ implorings of the harried parent. As far as she/he is concerned she saw a sweet, liked it and should have it. Words like health issues, or financial constraints are not part of the kindergarten vocabulary sessions. Standing behind the parent, you cannot help but feel sorry as you watch her struggle with the child who might as well be lying on the floor after throwing all the sweets to the ground.

Think about it, this is only a child who wants candy...just another day in the supermarket. God forbid, how would a child react in a hospital setting, surrounded by doctors and nurses where the mood is often anything but happy? Terrified obviously. The child might be coughing and have a high fever, making things worse and leaving him/her in a constant state of discomfort. Now picture having to take a test sample from this child. The sight of an approaching  nurse or doctor is likely to make him cry thinking that what follows is an injection...little does he know it is worse-- sputum collection. As children are unable to expectorate sputum upon request, methods such as sputum induction, gastric aspiration have to be used and this often involves passage of tubes down their throat. To say obtaining a sample for diagnosis from a child with presumptive TB is difficult, would be an understatement. It is a task that often requires an entire team to immobilize the child.

Then comes the second challenge associated with analysis of specimen. TB in children is mostly pauci-bacillary, meaning that the sputum specimen often contains just a few bacilli. Therefore, after all the efforts to acquire the specimen one might end up with a low yield and hence more tests and samples would be needed. This means more time and resources. However high TB burden countries are often resource challenged and this contributes not just to misdiagnosis, but also cases not being notified, especially in case of paediatric TB. The latest estimates show that in the 22 high TB burden countries over 650,000 children develop active TB disease every year with India predictably accounting for 27% of the total burden of paediatric TB. Also more than 53 million children who latently harbor the infection represent a huge reservoir for future disease. 

Laboratory diagnosis of childhood TB thus remains challenging due to the pauci-bacillary nature of the disease and the difficulties in obtaining good quality respiratory samples. Optimization of sampling methods and sample processing represent a critical aspect to address in order to improve current practice for childhood TB diagnosis. These issues of practical aspects of microbiological diagnostic evaluation for TB in children at different levels of health care were addressed during a workshop organized at the 45th Union World Conference on Lung Health in Barcelona.

Fearing that the challenges of mis/under diagnosis of TB in children are slowly paving the way to multidrug-resistant TB (MDR-TB), researchers are now recommending the use of Xpert MTB/RIF rather than sputum culture and microscopy for paediatric TB diagnosis. Speaking to Citizen News Service (CNS), Professor Mark Nicol from the University of Cape Town and the National Health Laboratory Service of South Africa, argued for the benefit of GeneXpert test, "It is faster and results can be produced within hours unlike with other methods where it could at times take weeks. GeneXpert is a more effective diagnostic tool than smear microscopy, which only detects one-third of the active TB cases, and chest X-ray which over-diagnoses TB in the children according to studies we have carried out. GeneXpert also seems to work better in HIV-infected children."

However Professor Nicol stressed that GeneXpert should not replace culture- the gold standard of TB diagnosis, in cases where culture is available. But GeneXpert can be very useful in rapid diagnosis and very valuable in cases of presumptive MDR-TB. The test might not be perfect, but it is practical-- which is the operative word when it comes to dealing with childhood TB. One better be practical when working with children.

In keeping with the need for practicality, in Cambodia practical measures of immobilization are being utilized as immobilization boards on sale are quite expensive. They have modified a cotton cloth that is given to the mother to immobilize her child and she can keep it once the sample is collected. Not only is it an innovative approach but it also works as an incentive for mothers to bring their children to the clinic for testing.

Similar solutions are needed when it comes to diagnosis of childhood TB. Studies are being done on working with stool samples and with evaluation of GeneXpert in children, strides are being made to ensure that released tools are not only innovative but practical.

Diana Esther Wangari, Citizen News Service - CNS
1 November 2014
(Global Alliance for TB Drug Development (TB Alliance) is supporting CNS Correspondents' Team to provide thematic coverage from the 45th Union World Conference on Lung Health in Spain. Email: diana@citizen-news.org)