Epidemic of complicated mumps in previously vaccinated young adults in the South-West of France.

OBJECTIVE: We report the features and diagnosis of complicated mumps in previously vaccinated young adults. PATIENTS AND METHODS: We retrospectively studied 7 cases of complicated mumps managed during 1 year at the Bordeaux University Hospital. The diagnosis was suggested by the clinical presentation and confirmed using specific RT-PCR. RESULTS: Five cases of meningitis, 1 of orchitis, and 1 of unilateral hearing impairment were identified. Each of the 7 patients had been previously vaccinated with MMR, 4 had received 2 doses of this vaccine. Blood tests revealed high rates of IgG antibodies, usually considered as sufficient for immunological protection, and every patient had at least 1 positive RT-PCR test for mumps. CONCLUSION: Outbreaks of complicated mumps may still occur despite a broad coverage of MMR vaccination. The clinical presentation suggested mumps but the final diagnosis could only be confirmed by genomic detection of the virus. Unusual viral strains with increased neurovirulence, insufficient population coverage associated with immunity decrease over time may explain outbreaks of complicated mumps. A full vaccine scheme of contact people or a third injection of vaccine for previously vaccinated people who are at risk of developing mumps are required to prevent further spreading of the disease during the outbreak.