This observational study was conducted to determine the diagnostic accuracy of ELISA for the detection of anti-Salmonella typhi lipopolysaccharide (LPS) salivary immunoglobulin A (IgA) antibodies in 37 children with culture confirmed typhoid, 30 febrile controls with an alternative diagnosis and 30 healthy controls. The test was positive in 33/37 (89.2%) cases of typhoid, but negative in all patients in the two control groups. Maximum absorbance of anti-LPS IgA was observed during the second and third weeks of typhoid, with a progressive decline thereafter. The sensitivity of ELISA was 71.4%, 100%, 100%, 9.1% and 0%, in first, second, third, fourth and fifth week of illness, respectively. Further large scale studies measuring salivary anti-LPS IgA antibodies are needed to confirm the potential of saliva-based serology in children with suspected typhoid.
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Competing interests None.
Ethics approval This study was conducted with the approval of the Institutional Ethics Committee, Jawaharlal Nehru Medical College, Faculty of Medicine, A.M.U., Aligarh, India.
Provenance and peer review Not commissioned; externally peer reviewed.