Serological diagnosis of mumps: Value of the titration of specific IgG.

INTRODUCTION: The aim of this study was to evaluate a cut-off point of the titration of IgG by ELISA in the diagnosis of mumps.

METHODS: A study was made of serum samples from 85 mumps cases (confirmed by PCR in saliva) and 2,351 controls of the general population of the Region of Madrid.

RESULTS: The IgM detection was positive in 21 cases (sensitivity of 24.7%). The best cut-off point corresponded to IgG titres ≥4,900 (sensitivity of 64.7% and specificity of 86.1%). Among 42 patients immunised with at least one dose of measles mumps, rubella vaccine IgM was detected in 4 cases. However, the detection of IgG ≥4,900 was positive in 29 (sensitivity of 69.0%).

CONCLUSIONS: An IgG result of ≥4.900 was almost 5 times more probable in a patient with mumps than in a non-infected patient. The detection of high titres of IgG against mumps could improve the IgM results in vaccinated people.