Mumps in the Czech Republic in 2013: Clinical Characteristics, Mumps Virus Genotyping, and Epidemiological Links.

Aim: The aim of the study was to map the incidence of mumps in the Czech Republic in terms of clinical symptoms, epidemiological links, and characteristics of circulating genotypes.

Methods: Patients with suspected mumps examined in the Infectious Diseases Clinic of the Na Bulovce Hospital in 2013 were enrolled in the study. Buccal swab specimens were tested by means of nucleic acid detection (RT-qPCR) and when positive, they were cultured in tissue culture. Sequencing was carried out using the BigDye Terminator v3.1 Cycle Sequencing Kit and Genetic Analyzer 3500. The SeqScape software was used for the analysis of sequencing data and filtering out low quality reads. The phylogenetic analysis and genotyping were performed using the Mega 6 software. To generate the phylogenetic tree, all sequences were aligned by the MAFFT tool and the alignment obtained was edited using the BioEdit software. In all patients, selected biochemical markers (C-reactive protein, white blood cell count and serum amylase) were measured. The EPIDAT system used for reporting infectious diseases, record keeping, and data analysis in the Czech Republic was the source of statistical data.

Results: Eighty-nine patients with suspected mumps were examined in the Na Bulovce Hospital and 65 of them were laboratory confirmed with mumps: 40 males (61.5%) and 25 females (38.5%). The mean age of the study cohort was 25.9 years (median age of 23 years, age range from 10 to 73 years) and 14 patients were under 18 years of age. Thirty-four (52.3%) patients were vaccinated in childhood, 28 (43.1%) were unvaccinated, and for three persons, vaccination data were not available. A severe course of the disease was reported in 15 (23.1%) patients. Fourteen of them needed hospitalization because of orchitis (9 males) and meningitis (5 patients). One patient with orchitis was treated on an outpatient basis. The need for hospitalization tended to be lower in the unvaccinated patients (14.7% vs. 35.7%, p=0.076). In 2013, 1,553 cases of mumps were reported to the EPIDAT system. Of these, 640 were laboratory confirmed. The most often reported complications were orchitis (90 cases, i.e. 10.3%) and meningitis (21 cases, i.e. 1.4%). Orchitis was diagnosed in 30.3% of the unvaccinated and in 6.4% of the vaccinated males. Meningitis occurred in 3.1% of the unvaccinated and in 1.0% of the vaccinated patients.

Conclusion: Despite the emergence of mumps among the vaccinated population, the present study has confirmed a positive effect of the vaccine, particularly on the incidence of complications and inflammatory markers. All 30 sequenced mumps virus strains were assigned to group G. A secondary vaccine failure due to waning immunity seems to be a plausible explanation for the rise in mumps cases.