Rapid blood test uses genetic response to diagnose children

A blood test that can discriminate between multiple infectious or inflammatory diseases could improve diagnosis and treatment for ill children.

The new type of test, which could provide a result in under 60 minutes, looks at the patterns of gene expression in the patient to distinguish between 18 different inflammatory or infectious diseases, rather than looking for the presence of a pathogen directly.

'When a child is brought into hospital with a fever, our initial approach is to treat based on the doctor's impression of the likely cause of the child's illness. But we may not know whether a fever is bacterial, viral or something else until hours or days after a child has been admitted, when their test results come back,' said senior author Professor Michael Levin, from the department of infectious diseases at Imperial College London. 'Such delays can stop patients getting the right treatment early on, so there is a clear and urgent need to improve diagnostics.'

To develop this new test, researchers analysed data from thousands of patients under the age of 16 to determine key genes and how they behaved in children and young people experiencing a range of illnesses including flu, meningitis, and E coli infection. RNA sequencing was used to understand which genes are turned on or off, before machine learning identified patterns that corresponded to 18 specific disease areas and pathogens.

While the research, published in Cell Press, estimates that this approach is more than 90 percent accurate, it only represents a proof-of-concept, and cannot be used in a clinical setting until it has been approved, which will require further testing and refinement. The researchers also hope that the approach could be adapted for use in adults, and expanded to include other types of illnesses.

The approach also has the possibility to reduce overuse of antibiotics, which contributes to antibiotic resistance. Broad-spectrum antibiotics are often given to patients before results come back, but if a bacterial infection can be ruled out quickly this would become unnecessary.

Professor Damian Roland, emergency children's doctor from University Hospitals of Leicester, who was not involved in the study told the BBC that the test 'opens up a gateway to a new model of care' but warned that: 'further research in avoiding any unintended consequences of early diagnosis will be vital to maximise the impact of this new innovation'.