Resurgence of mumps in Gujarat: Diagnostic insights, breakthrough infections, and immunization gaps

Objectives: The objective of this study was to evaluate suspected mumps cases presenting to a tertiary care center in Western Gujarat between March and September 2024, using molecular diagnostics by reverse transcription polymerase chain reaction (RT-PCR) and serological testing by immunoglobulin M enzyme-linked immunosorbent assay (IgM ELISA), and to analyze vaccination coverage and breakthrough infections. Materials and Methods: A hospital-based, cross-sectional study was conducted on 48 patients clinically diagnosed with mumps as per the World Health Organization case definition (acute onset of unilateral or bilateral parotitis lasting ≥2 days, with or without complications). Demographic data and vaccination history were recorded. Serum samples were tested for anti-mumps IgM by ELISA employing the NOVATEC Germany Mumps Virus IgM Antibody ELISA kit, and buccal swabs and urine samples were subjected to RT-PCR, targeting the small hydrophobic (SH) gene, for mumps viral RNA. Statistical analysis: Descriptive statistics were used to summarize demographic and diagnostic data. The sensitivity of RT-PCR on different specimen types was compared to ELISA results. Results: Of the 48 suspected cases, 31 (64.58%) were children (≤15 years) and 17 (35.42%) adults; males comprised 64.58%. Forty-three cases (89.58%) were confirmed by one or more tests. IgM ELISA was positive in 70.83% (34/48), and RT-PCR on buccal swabs also detected viral RNA in 70.83% (34/48), versus 20.83% (10/48) in urine. Seven samples with equivocal IgM results were RT-PCR negative. Two breakthrough infections occurred (a 3-year-old and a 26-year-old). Vaccination status was unvaccinated in 60.42% (29/48) and unknown in 35.42% (17/48). Conclusions: RT-PCR on buccal swabs offers superior sensitivity and should be regarded as the gold standard for early mumps diagnosis. The high proportion of unvaccinated and vaccination-uncertain individuals underscores the need to include measles, mumps, and rubella (MMR) in the Universal Immunization Program, alongside targeted awareness and booster-dose campaigns, to prevent future outbreaks.