16 February 2017 Blood test predicts onset of tuberculosis in young children
Researchers from the South African Tuberculosis Vaccine Initiative ( University of Cape Town), the universities of Stanford, Oxford and the London School of Hygiene & Tropical Medicine have shown that a blood test usually used to detect tuberculosis infection in adults can predict the onset of tuberculosis disease in young children.
The paper "Serial QuantiFERON testing and tuberculosis disease risk among young children: an observational cohort study," published by Andrews et al in The Lancet Respiratory Medicine on 15th February 2017, describes how infants with very high results of the QuantiFERON blood test, more than 10 times the cut-off value for a positive test, had exceptionally high risk of tuberculosis disease in subsequent months. The QuantiFERON test is commonly used in adults, particularly in developed countries, and conversion from a negative to positive test indicates recent infection with tuberculosis, often triggering drug treatment to prevent disease. The researchers analysed QuantiFERON results from a large tuberculosis vaccine trial conducted by the South African Tuberculosis Vaccine Initiative (SATVI) among more than 2,700 children in Worcester, near Cape Town, South Africa (Tameris et al, Lancet 2013). Until now, there has been scant evidence to suggest that the QuantiFERON test could or should be used in young children from tuberculosis endemic countries as an indication for preventive treatment. The new findings show that young South African children with very high QuantiFERON results, more than 10 times the recommended adult cut-off value for a positive test, had more than forty times greater risk of developing tuberculosis disease than children with a negative test. By contrast, children with a positive test at the usual adult cut-off value were likely to change back to negative when next tested.
“These new findings confirm that the QuantiFERON test performs very differently in young children than in adults. More importantly, we now know that a very high QuantiFERON result can be used to identify those children who are at highest risk of developing tuberculosis disease and who would benefit most from investigation and treatment,” said SATVI Professor Mark Hatherill. If confirmed in other studies, these new findings could lead to a revision of international guidelines for QuantiFERON testing and provide an opportunity to prevent at risk children from developing tuberculosis.
To view the journal article online click here.