Saliva tests more accurate than blood tests in detecting respiratory infections in kids

New Delhi: Saliva tests can more accurately determine the severity of recurrent respiratory infections in children than the standard blood test, a new study shows on Thursday.

Conducted by researchers from Radboudumc Amalia Children's Hospital and UMC Utrecht Wilhelmina Children's Hospital, Netherlands, the study reveals that low levels of broadly protective antibodies in saliva are linked to an increased likelihood of pneumonia episodes in children. This method offers valuable diagnostic information and is more comfortable for children.

Recurrent respiratory infections affect 10-15 per cent of children. Typically, paediatricians rely on blood tests to identify antibody deficiencies as an underlying condition, though these tests often yield limited results.

"This is challenging for paediatricians because we really want to help the children," said Dr. Lilly Verhagen, paediatric infectious disease specialist at Radboudumc.

"We explored whether saliva testing could better indicate disease severity, which would help determine which children need more intensive care or antibiotic treatment," she added.

The study, which involved 100 children with recurrent respiratory infections, found that saliva measurements were more effective than blood tests in indicating disease severity.

"We observed no correlation between blood antibodies and disease burden, but saliva revealed broadly protective antibodies that combat a range of pathogens. Children with lower levels of these antibodies experienced more severe infections," explained Mischa Koenen, doctoral student at UMC.

These broadly protective antibodies are abundant in the airways and were also found in the saliva of healthy siblings, parents, and caregivers. Researchers discovered that even pre-pandemic children's saliva contained antibodies capable of binding to the SARS-CoV-2 virus, the virus responsible for Covid-19 pandemic.

The study also explored the role of the airway microbiome, identifying Haemophilus influenzae as a bacterium strongly associated with severe respiratory infections. Children with high levels of this bacterium were more frequently ill during winter.

Future assessments may incorporate saliva and nasopharyngeal mucosal measurements to better evaluate children's care needs. This approach could lead to more effective treatments and child-friendly diagnostic practices, potentially replacing some follow-up blood tests, the team said.