Ongoing mumps outbreak in a student population with high vaccination coverage, Netherlands, 2010

Comparison of circulation patterns of mumps virus in the Netherlands and Spain (2015-2020)

Background

Mumps is a viral infection mainly characterized by inflammation of the parotid glands. Despite of vaccination programs, infections among fully vaccinated populations were reported. The World Health Organization (WHO) recommends molecular surveillance of mumps based on sequencing of the small hydrophobic (SH) gene. The use of hypervariable non-coding regions (NCR) as additional molecular markers was proposed in multiple studies. Circulation of mumps virus (MuV) genotypes and variants in different European countries were described in the literature. From 2010 to 2020, mumps outbreaks caused by genotype G were described. However, this issue has not been analyzed from a wider geographical perspective. In the present study, sequence data from MuV detected in Spain and in The Netherlands during a period of 5  years (2015- March 2020) were analyzed to gain insights in the spatiotemporal spread of MuV at a larger geographical scale than in previous local studies.

Methods

A total of 1,121 SH and 262 NCR between the Matrix and Fusion protein genes (MF-NCR) sequences from both countries were included in this study. Analysis of SH revealed 106 different haplotypes (set of identical sequences).

Results

Of them, seven showing extensive circulation were considered variants. All seven were detected in both countries in coincident temporal periods. A single MF-NCR haplotype was detected in 156 sequences (59.3% of total), and was shared by five of the seven SH variants, as well as three minor MF-NCR haplotypes. All SH variants and MF-NCR haplotypes shared by both countries were detected first in Spain.

Discussion

Our results suggest a transmission way from south to north Europe. The higher incidence rate of mumps in Spain in spite of similar immunization coverage in both countries, could be associated with higher risk of MuV exportation. In conclusion, the present study provided novel insights into the circulation of MuV variants and haplotypes beyond the borders of single countries. In fact, the use of MF-NCR molecular tool allowed to reveal MuV transmission flows between The Netherlands and Spain. Similar studies including other (European) countries are needed to provide a broader view of the data presented in this study.

Outbreaks of mumps genotype G viruses in the Netherlands between October 2019 and March 2020: clusters associated with multiple introductions

Background

From October 2019–March 2020, several clusters of mumps cases were identified in the Netherlands. Our objective was to describe cluster-associated mumps virus transmission using epidemiological and molecular information in order to help future mumps outbreak investigation and control efforts.

Methods

An epidemiological cluster includes ≥ 2 mumps cases with at least an epidemiological-link to a laboratory-confirmed mumps case. A molecular group includes ≥ 2 mumps cases with identical mumps virus sequences. Cases with symptom onset date between 1 October 2019 and 31 March 2020 reported through the National Notifiable Diseases Surveillance System were included. We described epidemiological and clinical characteristics of mumps cases. Sequence data was obtained from selected regions of mumps virus genomes (2270 nucleotides). Associations between epidemiological and molecular information were investigated.

Results

In total, 102 mumps cases were notified (90% laboratory-confirmed, 10% epidemiologically-linked). 71 out of 102 cases were identified as part of an epidemiological cluster and/or molecular group. Twenty-one (30%) of 71 cases were identified solely from epidemiological information, 25 (35%) solely from molecular surveillance, and 25 (35%) using both. Fourteen epidemiological clusters were identified containing a total of 46 (range: 2–12, median: 3) cases. Complete sequence data was obtained from 50 mumps genotype G viruses. Twelve molecular groups were identified containing 43 (range: 2–13) cases, dispersed geographically and timewise. Combined information grouped seven epidemiological clusters into two distinct molecular groups. The first lasting for 14 weeks, the other for 6. Additionally, one molecular group was detected, linked by geography and time but without an epidemiological-link.

Conclusions

Combined epidemiological and molecular information indicated ongoing mumps virus transmission from multiple introductions for extended time periods. Sequence analysis provided valuable insights into epidemiological clustering. If combined information is available in a timely manner, this would improve outbreak detection, generate further insight into mumps transmission, and guide necessary control measures.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06702-7.

Australia's notifiable disease status, 2016: Annual report of the National Notifiable Diseases Surveillance System

Abstract

In 2016, a total of 67 diseases and conditions were nationally notifiable in Australia. The states and territories reported 330,387 notifications of communicable diseases to the National Notifiable Diseases Surveillance System. Notifications have remained stable between 2015 and 2016. In 2016, the most frequently notified diseases were vaccine preventable diseases (139,687 notifications, 42% of total notifications); sexually transmissible infections (112,714 notifications, 34% of total notifications); and gastrointestinal diseases (49,885 notifications, 15% of total notifications). Additionally, there were 18,595 notifications of bloodborne diseases; 6,760 notifications of vectorborne diseases; 2,020 notifications of other bacterial infections; 725 notifications of zoonoses and one notification of a quarantinable disease.

Visual tools to assess the plausibility of algorithm-identified infectious disease clusters: an application to mumps data from the Netherlands dating from January 2009 to June 2016

Introduction

With growing amounts of data available, identification of clusters of persons linked to each other by transmission of an infectious disease increasingly relies on automated algorithms. We propose cluster finding to be a two-step process: first, possible transmission clusters are identified using a cluster algorithm, second, the plausibility that the identified clusters represent genuine transmission clusters is evaluated.

Aim

To introduce visual tools to assess automatically identified clusters.

Methods

We developed tools to visualise: (i) clusters found in dimensions of time, geographical location and genetic data; (ii) nested sub-clusters within identified clusters; (iii) intra-cluster pairwise dissimilarities per dimension; (iv) intra-cluster correlation between dimensions. We applied our tools to notified mumps cases in the Netherlands with available disease onset date (January 2009 – June 2016), geographical information (location of residence), and pathogen sequence data (n = 112). We compared identified clusters to clusters reported by the Netherlands Early Warning Committee (NEWC).

Results

We identified five mumps clusters. Three clusters were considered plausible. One was questionable because, in phylogenetic analysis, genetic sequences related to it segregated in two groups. One was implausible with no smaller nested clusters, high intra-cluster dissimilarities on all dimensions, and low intra-cluster correlation between dimensions. The NEWC reports concurred with our findings: the plausible/questionable clusters corresponded to reported outbreaks; the implausible cluster did not.

Conclusion

Our tools for assessing automatically identified clusters allow outbreak investigators to rapidly spot plausible transmission clusters for mumps and other human-to-human transmissible diseases. This fast information processing potentially reduces workload.

Mumps: an Update on Outbreaks, Vaccine Efficacy, and Genomic Diversity

Mumps is an acute viral infection characterized by inflammation of the parotid and other salivary glands. Persons with mumps are infectious from 2 days before through 5 days after parotitis onset, and transmission is through respiratory droplets. Despite the success of mumps vaccination programs in the United States and parts of Europe, a recent increase in outbreaks of mumps virus infections among fully vaccinated populations has been reported. Although the effectiveness of the mumps virus component of the measles-mumps-rubella (MMR) vaccine is suboptimal, a range of contributing factors has led to these outbreaks occurring in high-vaccination-coverage settings, including the intensity of exposure, the possibility of vaccine strain mismatch, delayed implementation of control measures due to the timeliness of reporting, a lack of use of appropriate laboratory tests (such as reverse transcription-PCR), and time since last vaccination. The resurgence of mumps virus infections among previously vaccinated individuals over the past decade has prompted discussions about new strategies to mitigate the risk of future outbreaks. The decision to implement a third dose of the MMR vaccine in response to an outbreak should be considered in discussions with local public health agencies. Traditional public health measures, including the isolation of infectious persons, timely contact tracing, and effective communication and awareness education for the public and medical community, should remain key interventions for outbreak control. Maintaining high mumps vaccination coverage remains key to U.S. and global efforts to reduce disease incidence and rates of complications.

A Single Point Mutation in the Mumps V Protein Alters Targeting of the Cellular STAT Pathways Resulting in Virus Attenuation

Mumps virus (MuV) is a neurotropic non-segmented, negative-stranded, enveloped RNA virus in the Paramyxovirus family. The 15.4 kb genome encodes seven genes, including the V/P, which encodes, among other proteins, the V protein. The MuV V protein has been shown to target the cellular signal transducer and activator of transcription proteins STAT1 and STAT3 for proteasome-mediated degradation. While MuV V protein targeting of STAT1 is generally accepted as a means of limiting innate antiviral responses, the consequence of V protein targeting of STAT3 is less clear. Further, since the MuV V protein targets both STAT1 and STAT3, specifically investigating viral antagonism of STAT3 targeting is challenging. However, a previous study reported that a single amino acid substitution in the MuV V protein (E95D) inhibits targeting of STAT3, but not STAT1. This provided us with a unique opportunity to examine the specific role of STAT 3 in MuV virulence in an in vivo model. Here, using a clone of a wild type MuV strain expressing the E95D mutant V protein, we present data linking inhibition of STAT3 targeting with the accelerated clearance of the virus and reduced neurovirulence in vivo, suggesting its role in promoting antiviral responses. These data suggest a rational approach to virus attenuation that could be exploited for future vaccine development.

Time series analysis of mumps and meteorological factors in Beijing, China

Background

Over the past decades there have been outbreaks of mumps in many countries, even in populations that were vaccinated. Some studies suggest that the incidence of mumps is related to meteorological changes, but the results of these studies vary in different regions. To date there is no reported study on correlations between mumps incidence and meteorological parameters in Beijing, China.

Methods

A time series analysis incorporating selected weather factors and the number of mumps cases from 1990 to 2012 in Beijing was performed. First, correlations between meteorological variables and the number of mumps cases were assessed. A seasonal autoregressive integrated moving average model with explanatory variables (SARIMAX) was then constructed to predict mumps cases.

Results

Mean temperature, rainfall, relative humidity, vapor pressure, and wind speed were significantly associated with mumps incidence. After constructing the SARIMAX model, mean temperature at lag 0 (β = 0.016, p < 0.05, 95% confidence interval 0.001 to 0.032) was positively associated with mumps incidence, while vapor pressure at lag 2 (β = ˗0.018, p < 0.05, 95% confidence interval ˗0.038 to ˗0.002) was negatively associated. SARIMAX (1, 1, 1) (0, 1, 1)₁₂ with temperature at lag 0 was the best predictive construct.

Conclusions

The incidence of mumps in Beijing from 1990 to 2012 was significantly correlated with meteorological variables. Combining meteorological variables, a predictive SARIMAX model that could be used to preemptively estimate the incidence of mumps in Beijing was established.

Electronic supplementary material

The online version of this article (10.1186/s12879-019-4011-6) contains supplementary material, which is available to authorized users.

Australia’s notifiable disease status, 2015: Annual report of the National Notifiable Diseases Surveillance System

In 2015, 67 diseases and conditions were nationally notifiable in Australia. States and territories reported a total of 320,480 notifications of communicable diseases to the National Notifiable Diseases Surveillance System, an increase of 16% on the number of notifications in 2014. In 2015, the most frequently notified diseases were vaccine preventable diseases (147,569 notifications, 46% of total notifications), sexually transmissible infections (95,468 notifications, 30% of total notifications), and gastrointestinal diseases (45,326 notifications, 14% of total notifications). There were 17,337 notifications of bloodborne diseases; 12,253 notifications of vectorborne diseases; 1,815 notifications of other bacterial infections; 710 notifications of zoonoses and 2 notifications of quarantinable diseases.

Laboratory testing and phylogenetic analysis during a mumps outbreak in Ontario, Canada

BACKGROUND

In September 2009, a mumps outbreak originated in New York and spread to Northeastern USA and Canada. This study compares the performance of different diagnostic testing methods used in Ontario and describes molecular characteristics of the outbreak strain.

METHODS

Between September 2009 and February 2010, specimens from suspect cases were submitted to Public Health Ontario Laboratory for mumps serology, culture and/or real-time reverse-transcriptase PCR (rRT-PCR) testing. rRT-PCR-positive specimens underwent genotyping at Canada's National Microbiology Laboratory. Whole genome sequencing was performed on four outbreak and three sporadic viral culture isolates.

RESULTS

Six hundred ninety-eight patients had IgM serology testing, of which 255 (37%) had culture and rRT-PCR. Among those, 35/698 (5%) were IgM positive, 39/255 (15%) culture positive and 47/255 (18%) rRT-PCR-positive. Buccal swabs had the highest rRT-PCR positivity (21%). The outbreak isolates were identical to that in the New York outbreak occurring at the same time. Nucleotide and amino acid identity with the Jeryl Lynn vaccine strain ranged from 85.0-94.5% and 82.4-99.4%, depending on the gene and coding sequences. Homology of the HN protein, the main immunogenic mumps virus protein, was found to be 94.5 and 95.3%, when compared to Jeryl Lynn vaccine major and minor components, respectively.

CONCLUSIONS

Despite higher sensitivity than serology, rRT-PCR testing is underutilized. Further work is needed to better understand the suboptimal match of the HN gene between the outbreak strain and the Jeryl Lynn vaccine strain.

Mumps Virus Nucleoprotein and Hemagglutinin-Specific Antibody Response Following a Third Dose of Measles Mumps Rubella Vaccine

Background

Recent mumps outbreaks among 2-dose measles mumps rubella (MMR) vaccine recipients have raised questions regarding the potential benefits of a third dose of vaccine (MMR3). If MMR3 provides a sustained elevation in mumps antibody, it may be beneficial for certain at-risk groups or as an outbreak control measure.

Methods

Sera were collected immediately prior to MMR3 and at 1 month and 1 year post-MMR3 from 656 healthy adults aged 18-28 years in a nonoutbreak setting. Immunoglobulin G (IgG) was measured by enzyme-linked immunosorbent assay (ELISA) using whole mumps virus (commercial ELISA), hemagglutinin (HN; major neutralizing target), and nucleoprotein (NP; immunodominant) antigens. ELISA measurements were compared with in vitro plaque reduction neutralization (PRN) titers, and baseline antibody was compared with post-MMR3 levels.

Results

There were modest but statistically significant (P < .05) increases in mumps antibody at 1 month post-MMR3 by all 3 ELISA methods and by PRN titer. At 1 year post-MMR3, mumps antibody declined toward baseline but remained elevated (P < .05). The correlation between PRN titers and ELISA measurements was poor (r² = .49), although sera with the highest amount of HN IgG also had the highest PRN titers.

Conclusions

Individuals with the lowest baseline PRN titers had the largest increase in frequency of samples that became positive for HN and NP by ELISA. A third dose of MMR may benefit certain individuals with a low level of mumps virus-neutralizing antibody, especially in the context of an outbreak or other high-risk setting. Additionally, poor correlation among serologic tests does not allow effective prediction of PRN titer by ELISA.

How will the MMR universal mass vaccination change the epidemiologic pattern of mumps? A 2012 Italian serosurvey

To investigate the changes in the epidemiologic pattern of mumps, we carried out a serosurvey among young adults from Apulia, Italy. A convenience sample of 1,764 blood donors were enrolled in 2012: 93.4% (95% confidence interval, 92.1-94.5) showed a positive antimumps immunoglobulin G titre, geometric mean titer was 2.05. Results were consistent with previously published data on the immunogenicity of mumps vaccine but showed a lack of immunity (10% of people aged 18-26 years susceptible for mumps). Future research must be focused on the long-time immunogenicity of the mumps vaccine.

ESCAIDE 2015: an operational scientific conference on infectious diseases for professionals from Europe and beyond

Binary file ES_Abstracts_Final_ECDC.txt matches

Mumps-specific cross-neutralization by MMR vaccine-induced antibodies predicts protection against mumps virus infection

BACKGROUND

Similar to other recent mumps genotype G outbreaks worldwide, most mumps patients during the recent mumps genotype G outbreaks in the Netherlands had received 2 doses of measles, mumps and rubella (MMR) vaccine during childhood. Here, we investigate the capacity of vaccine-induced antibodies to neutralize wild type mumps virus strains, including mumps virus genotype G.

METHODS

In this study, we tested 105 pre-outbreak serum samples from students who had received 2 MMR vaccine doses and who had no mumps virus infection (n=76), symptomatic mumps virus infection (n=10) or asymptomatic mumps virus infection (n=19) during the mumps outbreaks. In all samples, mumps-specific IgG concentrations were measured by multiplex immunoassay and neutralization titers were measured against the Jeryl Lynn vaccine strain and against wild type genotype G and genotype D mumps virus strains.

RESULTS

The correlation between mumps-specific IgG concentrations and neutralization titers against Jeryl Lynn was poor, which suggests that IgG concentrations do not adequately represent immunological protection against mumps virus infection by antibody neutralization. Pre-outbreak neutralization titers in infected persons were significantly lower against genotype G than against the vaccine strain. Furthermore, antibody neutralization of wild type mumps virus genotype G and genotype D was significantly reduced in pre-outbreak samples from infected persons as compared with non-infected persons. No statistically significant difference was found for the vaccine strain. The sensitivity/specificity ratio was largest for neutralization of the genotype G strain as compared with the genotype D strain and the vaccine strain.

CONCLUSIONS

The reduced neutralization of wild type mumps virus strains in MMR vaccinated persons prior to infection indicates that pre-outbreak mumps virus neutralization is partly strain-specific and that neutralization differs between infected and non-infected persons. Therefore, we recommend the use of wild type mumps virus neutralization assays as preferred tool for surveillance of protection against mumps virus infection.

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.

Factors influencing preclinical in vivo evaluation of mumps vaccine strain immunogenicity

Immunogenicity testing in animals is a necessary preclinical assay for demonstration of vaccine efficacy the results of which are often the basis for the decision whether to proceed or withdraw the further development of the novel vaccine candidate. However, in vivo assays are rarely, if at all, optimized and validated. Here we clearly demonstrate the importance of in vivo assay (mumps virus immunogenicity testing in guinea pigs) optimization for gaining reliable results and the suitability of Fractional factorial design of experiments (DoE) for such a purpose. By the use of DoE with resolution IV (2IV((4-1))) we clearly revealed that the parameters significantly increasing assay sensitivity were interval between animal immunizations followed by the body weight of experimental animals. The quantity (0 versus 2%) of the stabilizer (fetal bovine serum, FBS) in the sample was shown as non-influencing parameter in DoE setup. However, the separate experiment investigating only the FBS influence, and performed under other parameters optimally set, showed that FBS also influences the results of immunogenicity assay. Such finding indicated that (a) factors with strong influence on the measured outcome can hide the effects of parameters with modest/low influence and (b) the matrix of mumps virus samples to be compared for immunogenicity must be identical for reliable virus immunogenicity comparison. Finally the 3 mumps vaccine strains widely used for decades in the licensed vaccines were for the first time compared in an animal model, and results obtained were in line with their reported immunogenicity in human population supporting the predictive power of the optimized in vivo assay.

A Mumps Outbreak in Vojvodina, Serbia, in 2012 Underlines the Need for Additional Vaccination Opportunities for Young Adults

In 2012, mumps was introduced from Bosnia and Herzegovina to Vojvodina, causing an outbreak with 335 reported cases. The present manuscript analyses the epidemiological and laboratory characteristics of this outbreak, identifies its main causes and suggests potential future preventive measures. Sera of 133 patients were tested for mumps-specific antibodies by ELISA and 15 nose/throat swabs were investigated for mumps virus RNA by RT-PCR. IgG antibodies were found in 127 patients (95.5%). Mumps infection was laboratory-confirmed in 53 patients, including 44 IgM and 9 PCR positive cases. All other 282 cases were classified as epidemiologically-confirmed. More than half of the patients (n = 181, 54%) were 20–29 years old, followed by the 15–19 age bracket (n = 95, 28.4%). Twice as many males as females were affected (67% versus 33%). Disease complications were reported in 13 cases (3.9%), including 9 patients with orchitis and 4 with pancreatitis. According to medical records or anamnestic data, 190 patients (56.7%) were immunized with two doses and 35 (10.4%) with one dose of mumps-containing vaccine. The Serbian sequences corresponded to a minor genotype G variant detected during the 2011/2012 mumps outbreak in Bosnia and Herzegovina. Vaccine failures, the initial one-dose immunization policy and a vaccine shortage between 1999 and 2002 contributed to the outbreak. Additional vaccination opportunities should be offered to young adults during transition periods in their life trajectories.

Determinants of students' willingness to accept a measles-mumps-rubella booster vaccination during a mumps outbreak: a cross-sectional study

Background

Despite high vaccination coverage, a mumps outbreak that affected mainly vaccinated university students and their contacts took place in the Netherlands in the period 2009–2012. We presented university students with a hypothetical case in which we offered them a measles, mumps, and rubella (MMR) booster vaccination to control the mumps outbreak. The aim of this study was to get insight into the determinants of university students' willingness to accept this vaccination.

Methods

A questionnaire containing 38 items was developed for the purpose of assessing students' willingness and the psychosocial and social demographic determinants influencing their willingness to accept an MMR booster vaccination. In addition, we explored how organisational characteristics influenced the willingness to be vaccinated. Data were collected at six Dutch universities; a total of 790 students from various faculties were invited to participate. This was a convenience sampling procedure.

Results

687 university students participated (response rate 87.0 %) and 60.4 % of the participants said they would be willing accept the hypothetical MMR booster vaccination. The perceived seriousness of mumps (OR 6.1) was the most important predictor of willingness to accept vaccination. Students who expected the MMR vaccination to be effective and to prevent individual illness and who believed their own vaccination would help stop the epidemic were more likely to be willing than others. The students were more willing to accept vaccination when they perceived that the social norms of significant others and the government favoured vaccination. Organisational characteristics, such as offering vaccination cost free and offering it at the university site, increased students’ willingness.

Conclusion

During a mumps outbreak, university students were generally willing to accept a hypothetical MMR booster vaccination. Risk perception, outcome expectations, perceived social norms, and organisational characteristics should be taken into account in the planning of any vaccination campaign for university students during an outbreak of an infectious disease.

Resurgence of mumps in Korea

Routine vaccination against mumps has markedly reduced its incidence. However, the incidence of mumps continuously has increased since 2007. In 2013, a large mumps epidemic occurred in Korea, and this epidemic is still an ongoing problem. This epidemic occurred primarily in school settings and affected vaccinated adolescents, predominantly male students. The recent resurgence of mumps is caused by multiple factors: suboptimal effectiveness of the current mumps vaccines, use of the Rubini strain vaccine, waning immunity in the absence of natural boosting due to the marked reduction in the mumps incidence, genotype mismatch between the vaccine and circulating mumps virus strains, and environmental conditions that foster intense exposures. Containment of mumps outbreaks is challenging because the sensitivity of diagnostic tests is low among vaccinees and control measures are less efficient because of the inherent nature of the mumps virus. Despite the suboptimal vaccine effectiveness in outbreak settings, maintaining the high vaccine coverage is an important strategy to prevent mumps outbreaks, given that the routine use of mumps vaccines has substantially reduced the incidence of mumps and its complications as compared with that in the pre-vaccine era. In order to control the current mumps epidemic and prevent further outbreaks, we need to better understand the dynamics of mumps among vaccinated populations and the changing epidemiology in Korea. Concerted efforts should be made to systematically monitor the immunization status of the Korean population and to improve diagnosis efficiency. Furthermore, more effective mumps vaccines need to be developed in the future.

Epidemic of mumps among vaccinated persons, The Netherlands, 2009-2012

To analyze the epidemiology of a nationwide mumps epidemic in the Netherlands, we reviewed 1,557 notified mumps cases in persons who had disease onset during September 1, 2009–August 31, 2012. Seasonality peaked in spring and autumn. Most case-patients were males (59%), 18–25 years of age (67.9%), and vaccinated twice with measles-mumps-rubella vaccine (67.7%). Nearly half (46.6%) of cases occurred in university students or in persons with student contacts. Receipt of 2 doses of vaccine reduced the risk for orchitis, the most frequently reported complication (vaccine effectiveness [VE] 74%, 95% CI 57%–85%); complications overall (VE 76%, 95% CI 61%–86%); and hospitalization (VE 82%, 95% CI 53%–93%). Over time, the age distribution of case-patients changed, and proportionally more cases were reported from nonuniversity cities (p<0.001). Changes in age and geographic distribution over time may reflect increased immunity among students resulting from intense exposure to circulating mumps virus.

[An outbreak of mumps in a high school: Estimation of vaccine effectiveness. Zaragoza 2011]

INTRODUCTION

Mumps outbreaks continue to occur, even after the consolidation of vaccination programs. An outbreak of mumps occurred in a high school in Zaragoza during December 2011.

OBJECTIVE

To describe the outbreak and estimate vaccine effectiveness.

METHODS

CASE DEFINITION

unilateral or bilateral swelling of the parotid or other salivary glands for three or more days without any other apparent cause.

REFERENCE POPULATION

People attending the 'Parque Goya' High School or with transmission chain origin in the High School.

OUTBREAK PERIOD

From two days before the onset of symptoms of the first case to five days after the last case. Samples were collected for virus confirmation (IgM, urine culture and oropharyngeal exudate), and isolates were processed for genotyping. A retrospective cohort study was performed in two high school classrooms to estimate vaccine efficacy. Public health authorities conducted active surveillance, isolation of cases, and vaccination of susceptible contacts.

RESULTS

There were 27 cases. Twenty-one (77.8%) were vaccinated with two doses of Measles-Mumps-Rubella vaccine. Twelve (44%) were confirmed microbiologically. G1 genotype was determined in six cases. According to the cohort study, vaccine efficacy for one dose was 34% (95%CI: -44 to 70), and was 67% (95%CI: 28 to 83) for two doses.

CONCLUSIONS

Vaccine effectiveness was lower than expected. Early detection and isolation of cases have been instrumental in preventing new cases in schools.

Complete genome sequence of mumps virus genotype g from a vaccinated child in franceville, southeastern Gabon, in 2013

The genome of mumps virus (MuV), a member of the family Paramyxoviridae of the genus Rubulavirus, consists of a single-stranded, negative-sense, nonsegmented RNA. Here, we report the first whole-genome sequence of 15,263 nucleotides of a mumps virus strain from a 6-year-old vaccinated boy in Franceville, southeastern Gabon.

Mumps virus infection in vaccinated patients can be detected by an increase in specific IgG antibodies to high titres: a retrospective study

Mumps outbreaks in highly vaccinated populations with genotype G have been reported repeatedly. Detection of these outbreaks can be difficult in a setting with relatively high vaccination coverage when acute cases of mumps are routinely diagnosed by IgM serology since this marker is not reliable for diagnosis of mumps re-infection. To learn whether diagnostic tests performed in a large private laboratory may be useful to detect mumps outbreaks retrospectively, we reviewed the results of almost 7000 mumps tests. Two groups were compared: group 1 comprised of 3438 samples from patients submitted by physicians and clinicians (it was assumed that these patients visited their doctor due to acute disease). Group 2 comprised of 3398 samples submitted from company medical officers and occupational physicians. Since these patients usually attend for routine check-ups and certification of immunity to vaccine-preventable diseases, these samples comprised a control group. From July 2010 to May 2011, a mumps virus outbreak with more than 300 cases occurred in Bavaria, Southeast Germany. Our study includes samples received for serological mumps tests from January 2009 until December 2011 (36 months). The two groups were analysed with regard to the number of IgM-positive cases per month and the level of IgG titre. We found a marked increase for both parameters in group 1 during the time of the outbreak, while the samples submitted by the occupational medical physicians did not display significant alterations. These parameters reflect the outbreak with high accuracy, indicating that a retrospective analysis of IgG titres may be a useful tool for detection of mumps outbreaks when, as was the case in Germany, (i) a nationwide notification system has not been implemented and (ii) a highly vaccinated population is affected.

Mumps antibody response in young adults after a third dose of measles-mumps-rubella vaccine

Baseline mumps antibody titers were high-seropositive for 93.4% of subjects, low-seropositive for 5.8%, and seronegative for <1%. One month after a third measles-mumps-rubella vaccine dose, mumps titers had a modest but significant increase. One year later, titers returned to near baseline.

Background

 Mumps outbreaks in populations with high 2-dose measles-mumps-rubella (MMR) vaccine coverage raise the question whether a third dose of MMR vaccine (MMR3) is needed. However, data on the immunogenicity of MMR3 are limited. We assessed mumps virus neutralizing antibody levels pre- and post-MMR3 in a nonoutbreak setting.

Methods

 Mumps antibody titers were assessed at baseline, 1 month, and 1 year after MMR3 in subjects aged 18–28 years.

Results

 At baseline, 5 of 656 (0.8%) subjects had seronegative mumps neutralizing antibody titers and 38 (5.8%) had low titers. One year post-MMR3, these numbers declined to 3 (0.5%) and 16 (2.4%), respectively. Subjects with low baseline titers were more likely to have low 1-month and 1-year titers (R² = 0.81–0.87, P < .0001). Compared to baseline, geometric mean titers were significantly higher at 1 month (P < .0001) and 1 year (P < .01) post-MMR3; however, reverse cumulative distribution curves showed only minimal shifts in mumps titers from baseline to 1 month and 1 year.

Conclusions

 Very few subjects had negative or low baseline mumps titers. Nonetheless, mumps titers had modest but significant increases when measured 1 month and 1 year post-MMR3. This temporary increase in titers could decrease susceptibility to disease during outbreaks, but may have limited value for routine use in vaccinated populations.

Two major mumps genotype G variants dominated recent mumps outbreaks in the Netherlands (2009–2012)

During three seasons of mumps outbreaks in the Netherlands (September 2009–August 2012), 822 mumps cases were laboratory-confirmed at the National Institute for Public Health and the Environment (RIVM). Most patients were vaccinated young adults. Given the protracted endemic circulation, we studied the genetic diversity and changes of mumps virus over a period of 3 years. Phylogenetic analysis of the small hydrophobic (SH) gene (316 bp) was performed on a representative set of 808 specimens that tested positive for mumps via PCR. Additionally, the haemagglutinin/neuraminidase (HN) gene (1749 bp) and fusion (F) gene (1617 bp) were sequenced for a subset of samples (n = 17). Correlations between different sequence types and epidemiological and clinical data were investigated. The outbreaks in the Netherlands were dominated by two SH gene sequence types within genotype G, termed MuVs/Delft.NLD/03.10 (variant 1) and MuVs/Scheemda.NLD/12.10 (variant 2). Sequence analysis of the HN and F genes indicated that the outbreaks were initiated by separately introduced genetic lineages. The predominance of variant 2 by the end of the first outbreak season could not be explained by any of the epidemiological factors investigated. Orchitis was more frequently reported in males infected with variant 2, irrespective of age and vaccination status. These findings illustrate genetic heterogeneity of an emerging mumps genotype, and raise questions about the mechanisms driving mumps epidemiology and immunity in relation to vaccination.

Smoking and older age associated with mumps in an outbreak in a group of highly-vaccinated individuals attending a youth club party, the Netherlands, 2012

We describe a mumps outbreak in a highly-vaccinated population attending a party at a youth club. In a retrospective cohort study with 60 of approximately 100 participants responding, vaccination status was verified for 58/59 respondents, of whom 54 were vaccinated twice and four once. The attack rate was 22% (13 cases, all vaccinated), with smoking at the party (risk ratio (RR) 3.1; 95% confidence interval (CI): 1.6–6.0, p=0.001) and age ≥21 years (RR 4.7; 95% CI: 2.1–10.2, p<0.0001) as risk factors for disease in the binominal regression analysis. Mild upper respiratory illness was also highly prevalent in those who did not meet the mumps case definition (n=46) after the party, suggesting that mumps virus infection may cause mild disease in vaccinated individuals. Our investigation adds toevidence that crowded social events and smoking may facilitate spread of mumps virus among vaccinated populations, with waning immunity playing a role. The suggestion that mumps virus infection in vaccinated individuals may manifest as mild upper respiratory illness could have implications for transmission and warrants further investigation.

Lower transplacental antibody transport for measles, mumps, rubella and varicella zoster in very preterm infants

BACKGROUND

Maternal antibodies, transported over the placenta during pregnancy, contribute to the protection of infants from infectious diseases during the first months of life. In term infants, this protection does not last until the first recommended measles-mumps-rubella vaccination at 14 months in the Netherlands, while these viruses still circulate. The aim of the study was to investigate the antibody concentration against measles, mumps, rubella and varicella (MMRV) in mothers and preterm infants or healthy term infants at birth.

METHODS

Antibody concentrations specific for MMRV were measured in cord blood samples from preterm (gestational age <32 weeks and/or birth weight <1500 g) and term infants, and matched maternal serum samples, using a fluorescent bead-based multiplex immune-assay.

RESULTS

Due to lower placental transfer ratios of antibodies against MMRV in 96 preterm infants (range 0.75-0.87) compared to 42 term infants (range 1.39-1.65), the preterm infants showed 1.7-2.5 times lower geometric mean concentrations at birth compared to term infants. Maternal antibody concentration is the most important determinant of infant antibody concentration against MMRV.

CONCLUSIONS

Preterm infants benefit to a lesser extent from maternal antibodies against measles, mumps, rubella and varicella than term infants, posing them even earlier at risk for infectious diseases caused by these still circulating viruses.

Mumps postexposure prophylaxis with a third dose of measles-mumps-rubella vaccine, Orange County, New York, USA

Although the measles-mumps-rubella (MMR) vaccine is not recommended for mumps postexposure prophylaxis (PEP), data on its effectiveness are limited. During the 2009–2010 mumps outbreak in the northeastern United States, we assessed effectiveness of PEP with a third dose of MMR vaccine among contacts in Orthodox Jewish households who were given a third dose within 5 days of mumps onset in the household’s index patient. We compared mumps attack rates between persons who received a third MMR dose during the first incubation period after onset in the index patient and 2-dose vaccinated persons who had not. Twenty-eight (11.7%) of 239 eligible household members received a third MMR dose as PEP. Mumps attack rates were 0% among third-dose recipients versus 5.2% among 2-dose recipients without PEP (p = 0.57). Although a third MMR dose administered as PEP did not have a significant effect, it may offer some benefits in specific outbreak contexts.

Epidemiology and the economic assessment of a mumps outbreak in a highly vaccinated population, Orange County, New York, 2009-2010

Studies assessing the economic burden of a mumps outbreak in a highly vaccinated population are limited. The Orange County Health Department (OCHD), New York State Department of Health (NYS DOH), and the Centers for Disease Control and Prevention conducted a mumps investigation in an affected village with a highly vaccinated population. To understand the epidemiology, standardized mumps case definition and active surveillance were used to identify mumps cases. In addition, an economic assessment of a combined outbreak investigation and third dose measles-mumps-rubella (MMR) vaccine intervention conducted by OCHD and NYS DOH was performed; estimated by retrospectively evaluating public health response-related activities including use of a third dose of MMR vaccine. From September 24, 2009, through June 15, 2010, 790 mumps cases were reported-64% were male and highest attack rate was among 11-17 year age group (99.1 cases per 1000 individuals). Of the 658 cases with known vaccination history, 83.6% had documentation of 2 doses of mumps containing vaccine. No deaths were reported. The 2 major exposure settings were schools (71.8%) and households (22.5%). Approximately 7736 h of public health personnel time were expended with the total approximate cost of US $463,000, including US $34,392 for MMR vaccine-the estimated cost per household was US $827. Mumps continues to be endemic in many parts of the world, resulting in importations into the United States. Large mumps outbreaks similar to this in highly vaccinated populations may require considerable investigation and control activities.

In vitro inhibition of mumps virus by retinoids

BACKGROUND

Mumps virus (MuV) is a highly infectious paramyxovirus closely related to measles virus (MeV). Despite the availability of a mumps vaccine, outbreaks continue to occur and no treatment options are available. Vitamin A and other naturally occurring retinoids inhibit the replication of MeV in vitro.

METHODS

Anti-viral effects of retinoids were observed in cell culture using the myelomonocytic U937, NB4/R4, and Huh7/7.5 cells. Observations of anti-viral effect were quantified using TCID50 analysis. Molecular properties of the antiviral effect were analysed using quantitative RT-PCR and western blot.

RESULTS

The current work demonstrates that retinoids inhibit MuV in vitro due to up-regulation of type I interferon (IFN) and IFN stimulated genes. This effect is mediated by nuclear retinoid receptor signalling and RIG-I is required. The antiviral retinoid-induced state makes cells less permissive to viral replication from subsequent challenge with either MuV or MeV for less than 12 hours.

CONCLUSIONS

These results demonstrate that retinoids inhibit MuV replication in uninfected bystander cells through a retinoid inducible gene I (RIG-I), retinoic acid receptor (RAR) and IFN dependent manner making them refractory to subsequent rounds of viral replication. These observations raise the possibility that pharmacological doses of retinoids might have clinical benefit in MuV infection.

Outbreak-related mumps vaccine effectiveness among a cohort of children and of young adults in Germany 2011

Mumps outbreaks in populations with high 2-dose vaccination coverage and among young adults are increasingly reported. However, data on the duration of vaccine-induced protection conferred by mumps vaccines are scarce. As part of a supra-regional outbreak in Germany 2010/11, we conducted two retrospective cohort studies in a primary school and among adult ice hockey teams to determine mumps vaccine effectiveness (VE). Via questionnaires we collected information on demography, clinical manifestations, and reviewed vaccination cards. We estimated VE as 1-RR, RR being the rate ratio of disease among two-times or one-time mumps-vaccinated compared with unvaccinated persons. The response rate was 92.6% (100/108--children cohort) and 91.7% (44/48--adult cohort). Fourteen cases were identified in the children and 6 in the adult cohort. In the children cohort (mean age: 9 y), 2-dose VE was 91.9% (95% CI 81.0-96.5%). In the adult cohort (mean age: 26 y), no cases occurred among the 13 2-times vaccinated, while 1-dose VE was 50.0% (95% CI -9.4-87.1%). Average time since last vaccination showed no significant difference for cases and non-cases, but cases were younger at age of last mumps vaccination (children cohort: 2 vs. 3 y, P=0.04; adult cohort: 1 vs. 4 y, P=0.03). We did not observe signs of waning immunity in the children cohort. Due to the small sample size VE in the adult cohort should be interpreted with caution. Given the estimated VE, very high 2-dose vaccination coverage is required to prevent future outbreaks. Intervention efforts to increase coverage must especially target young adults who received<2 vaccinations during childhood.

Epidemiology of a mumps outbreak in a highly vaccinated island population and use of a third dose of measles-mumps-rubella vaccine for outbreak control--Guam 2009 to 2010

BACKGROUND

Despite high 2-dose measles-mumps-rubella (MMR) vaccine coverage, a large mumps outbreak occurred on the US Territory of Guam during 2009 to 2010, primarily in school-aged children.

METHODS

We implemented active surveillance in April 2010 during the outbreak peak and characterized the outbreak epidemiology. We administered third doses of MMR vaccine to eligible students aged 9-14 years in 7 schools with the highest attack rates (ARs) between May 18, 2010, and May 21, 2010. Baseline surveys, follow-up surveys and case-reports were used to determine mumps ARs. Adverse events postvaccination were monitored.

RESULTS

Between December 1, 2009, and December 31, 2010, 505 mumps cases were reported. Self-reported Pohnpeians and Chuukese had the highest relative risks (54.7 and 19.7, respectively) and highest crowding indices (mean: 3.1 and 3.0 persons/bedroom, respectively). Among 287 (57%) school-aged case-patients, 270 (93%) had ≥2 MMR doses. A third MMR dose was administered to 1068 (33%) eligible students. Three-dose vaccinated students had an AR of 0.9/1000 compared with 2.4/1000 among students vaccinated with ≤2 doses >1 incubation period postintervention, but the difference was not significant (P = 0.67). No serious adverse events were reported.

CONCLUSIONS

This mumps outbreak occurred in a highly vaccinated population. The highest ARs occurred in ethnic minority populations with the highest household crowding indices. After the third dose MMR intervention in highly affected schools, 3-dose recipients had an AR 60% lower than students with ≤2 doses, but the difference was not statistically significant and the intervention occurred after the outbreak peaked. This outbreak may have persisted due to crowding at home and high student contact rates.

Seroprevalence of mumps in The Netherlands: dynamics over a decade with high vaccination coverage and recent outbreaks

Here we present mumps virus specific antibody levels in a large cross-sectional population-based serosurveillance study performed in the Netherlands in 2006/2007 (n = 7900). Results were compared with a similar study (1995/1996) and discussed in the light of recent outbreaks. Mumps antibodies were tested using a fluorescent bead-based multiplex immunoassay. Overall seroprevalence was 90.9% with higher levels in the naturally infected cohorts compared with vaccinated cohorts. Mumps virus vaccinations at 14 months and 9 years resulted in an increased seroprevalence and antibody concentration. The second vaccination seemed to be important in acquiring stable mumps antibody levels in the long term. In conclusion, the Dutch population is well protected against mumps virus infection. However, we identified specific age- and population groups at increased risk of mumps infection. Indeed, in 2007/2008 an outbreak has occurred in the low vaccination coverage groups emphasizing the predictive value of serosurveillance studies.

Environmental factors potentially associated with mumps transmission in yeshivas during a mumps outbreak among highly vaccinated students: Brooklyn, New York, 2009-2010

During 2009-2010, a large US mumps outbreak occurred affecting two-dose vaccinated 9th-12th grade Orthodox Jewish boys attending all-male yeshivas (private, traditional Jewish schools). Our objective was to understand mumps transmission dynamics in this well-vaccinated population. We surveyed 9th-12th grade male yeshivas in Brooklyn, NY with reported mumps case-students between 9/1/2009 and 3/30/2010. We assessed vaccination coverage, yeshiva environmental factors (duration of school day, density, mixing, duration of contact), and whether environmental factors were associated with increased mumps attack rates. Ten yeshivas comprising 1769 9th-12th grade students and 264 self-reported mumps cases were included. The average yeshiva attack rate was 14.5% (median: 13.5%, range: 1-31%), despite two-dose measles-mumps-rubella vaccine coverage between 90-100%. School duration was 9-15.5 h/day; students averaged 7 h face-to-face/day with 1-4 study partners. Average daily mean density was 6.6 students per 100 square feet. The number of hours spent face-to-face with a study partner and the number of partners per day showed significant positive associations (p < 0.05) with classroom mumps attack rates in univariate analysis, but these associations did not persist in multivariate analysis. This outbreak was characterized by environmental factors unique to the yeshiva setting (e.g., densely populated environment, prolonged face-to-face contact, mixing among infected students). However, these features were present in all included yeshivas, limiting our ability to discriminate differences. Nonetheless, mumps transmission requires close contact, and these environmental factors may have overwhelmed vaccine-mediated protection increasing the likelihood of vaccine failure among yeshiva students.

Impact of a third dose of measles-mumps-rubella vaccine on a mumps outbreak

BACKGROUND AND OBJECTIVE

During 2009-2010, a northeastern US religious community experienced a large mumps outbreak despite high 2-dose measles-mumps-rubella (MMR) vaccine coverage. A third dose of MMR vaccine was offered to students in an affected community in an effort to control the outbreak.

METHODS

Eligible sixth- to 12th-grade students in 3 schools were offered a third dose of MMR vaccine. Baseline and follow-up surveys and physician case reports were used to monitor mumps attack rates (ARs). We calculated ARs for defined 3-week periods before and after the intervention.

RESULTS

Of 2265 eligible students, 2178 (96.2%) provided documentation of having received 2 previous doses of MMR vaccine, and a high proportion (1755 or 80.6%) chose to receive an additional vaccine dose. The overall AR for all sixth- to 12th-grade students declined from 4.93% in the prevaccination period to 0.13% after vaccination (P < .001). Villagewide, overall AR declined by 75.6% after the intervention. A decline occurred in all age groups but was significantly greater (96.0%) among 11- to 17-year-olds, the age group targeted for vaccination, than among all other age groups. The proportions of adverse events reported were lower than or within the range of those in previous reports of first- and second-dose MMR vaccine studies.

CONCLUSIONS

This is the first study to assess the impact of a third MMR vaccine dose for mumps outbreak control. The decline in incidence shortly after the intervention suggests that a third dose of MMR vaccine may help control mumps outbreaks among populations with preexisting high 2-dose vaccine coverage.

Antigenic differences between vaccine and circulating wild-type mumps viruses decreases neutralization capacity of vaccine-induced antibodies

A recent resurgence of mumps in doubly vaccinated cohorts has been observed, identifying genotype G as the current predominant genotype. In this study, the neutralization efficacy of guinea pig sera immunized with three vaccine viruses: L-Zagreb, Urabe AM9 and JL5, was tested against seven mumps viruses: three vaccine strains and four wild-type strains (two of genotype G, one of genotype C, one of genotype D) isolated during 1998–2011. All sera neutralized all viruses although at different levels. The neutralization efficiency of sera decreases several fold by temporal order of virus isolation. Therefore, we concluded that gradual evolution of mumps viruses, rather than belonging to a certain genotype, results in an antigenic divergence from the vaccine strains that decrease the neutralization capacity of vaccine-induced antibodies. Moreover, the amino-acid sequence alignment revealed three new potentially relevant regions for escape from neutralization, i.e. 113–130, 375–403 and 440–443.

Seroprevalence of measles-, mumps- and rubella-specific IgG antibodies in German children and adolescents and predictors for seronegativity

We have undertaken a seroprevalence study with more than 13,000 children, who had been included in the German KIGGS survey, a representative sample of children and adolescents 0-17 years of age. The IgG titres against measles, mumps and rubella were determined in 1 to 17 year olds While 88.8% of the children were MMR-vaccinated at least once, 76.8% of children aged 1 to 17 years showed prevalence of antibodies to MMR. The highest seronegativity was seen with respect to mumps. Gender differences were most pronounced with regard to rubella IgG titres: girls aged 14 to 17 years were best protected, although seronegativity in 6.8% of this vulnerable group still shows the need of improvement. Search for predictors of missing seroprevalence identified young age to be the most important predictor. Children living in the former West and children born outside of Germany had a higher risk of lacking protection against measles and rubella, while children with a migration background but born in Germany were less often seronegative to measles antibodies than their German contemporaries. An association of seronegativity and early vaccination was seen for measles but not for mumps and rubella. A high maternal educational level was associated with seronegativity to measles and rubella. In vaccinated children, seronegativity was highest for mumps and lowest for rubella. For mumps, high differences were observed for seronegativity after one-dose and two-dose vaccination, respectively. Seronegativity increases as time since last vaccination passes thus indicating significant waning effects for all three components of MMR.

Mumps outbreak among vaccinated university students associated with a large party, the Netherlands, 2010

We investigated a mumps outbreak within a highly vaccinated university student population in the Netherlands by conducting a retrospective cohort study among members of university societies in Delft, Leiden and Utrecht. We used an online questionnaire asking for demographic information, potential behavioural risk factors for mumps and the occurrence of mumps. Vaccine status from the national vaccination register was used. Overall, 989 students participated (20% response rate). Registered vaccination status was available for 776 individuals, of whom 760 (98%) had been vaccinated at least once and 729 (94%) at least twice. The mumps attack rate (AR) was 13.2% (95%CI 11.1-15.5%). Attending a large student party, being unvaccinated and living with more than 15 housemates were independently associated with mumps ((RR 42 (95%CI 10.1-172.4); 3.1 (95%CI 1.7-5.6) and 1.8 (95%CI 1.1-3.1), respectively). The adjusted VE estimate for two doses of MMR was 68% (95%CI 41-82%). We did not identify additional risk factors for mumps among party attendees. The most likely cause of this outbreak was intense social mixing during the party and the dense communal living environment of the students. High coverage of MMR vaccination in childhood did not prevent an outbreak of mumps in this student population.

Seroepidemiology of the recent mumps virus outbreaks in Ireland

BACKGROUND

Two recent mumps outbreaks have occurred in Ireland in 2004/2005 and 2008/2009.

OBJECTIVES

To retrospectively investigate any potential shifts in the gender bias and age profile and to identify cohorts who are maintaining mumps virus in circulation.

STUDY DESIGN

2600 cases of acute mumps infection, as determined by the presence of mumps-specific IgM in sera and oral fluids, were confirmed at the National Virus Reference Laboratory.

RESULTS

Acute mumps infection occurred more frequently in males with a ratio of approximately 2:1 in the 1-9 and 10-19 years old age groups. A 3:2 ratio was observed in the 20-29 years old cohort and the 30+ age group did not show a gender bias. Serological evidence of prior immunological exposure to mumps virus, as determined by the presence of mumps-specific IgG, was high and similar in males and females of all age cohorts (93.1-100%). A significant increase in the number of acute mumps cases in the ≥30 years old age group was observed. This increase was most striking in the periods between the outbreaks (71.1% in 2007 and 56.2% in 2010).

CONCLUSIONS

Acute mumps infection showed a male gender bias. The consistent and significant increase of mumps infection in the ≥30 years old age group which is also evident in the periods between outbreaks suggests that this may be the cohort maintaining the mumps virus in circulation.

The V protein of mumps virus plays a critical role in pathogenesis

Mumps virus (MuV) causes an acute infection in humans characterized by a wide array of symptoms ranging from relatively mild manifestations, such as parotitis, to more-severe complications, such as meningitis and encephalitis. Widespread mumps vaccination has reduced mumps incidence dramatically; however, outbreaks still occur in vaccinated populations. The V protein of MuV, when expressed in cell culture, blocks interferon (IFN) expression and signaling and interleukin-6 (IL-6) signaling. In this work, we generated a recombinant MuV incapable of expressing the V protein (rMuVΔV). The rescued MuV was derived from a clinical wild-type isolate from a recent outbreak in the United States (MuV(Iowa/US/06), G genotype). Analysis of the virus confirmed the roles of V protein in blocking IFN expression and signaling and IL-6 signaling. We also found that the rMuV(Iowa/US/06)ΔV virus induced high levels of IL-6 expression in vitro, suggesting that V plays a role in reducing IL-6 expression. In vivo, the rMuV(Iowa/US/06)ΔV virus was highly attenuated, indicating that the V protein plays an essential role in viral virulence.

[Study of a population-wide epidemic outbreak of mumps virus G1 in Jerez de la Frontera (Spain)]

OBJECTIVES

To characterize the mumps outbreak, assess the effectiveness of vaccines and discuss prevention and control measures.

DESIGN

Observational cross-sectional study of cases by person, place, and time.

LOCATION

City Jerez de la Frontera and 8 Primary Care centres.

PARTICIPANTS

A total of 116 cases of mumps were reported throughout seven months, with the last case in June 2008.

MEASUREMENTS

MAIN OUTCOMES

age, sex, place of study or work, symptoms start date, clinical description, complications, and genotype of virus isolation, history and vaccination compositions. Calculation of total vaccine effectiveness. Active case finding and contact studies were performed on the families, work places and leisure areas.

RESULTS

The mean age of the cases was 16.24 years(SD 10.6). The majority (68.96%) of the cases were children at school and 31.03% arose from family and work areas. Mumps vaccine coverage rates were above 90%. The complete vaccine effectiveness (2 doses); for those under 20 years-old it was: 99.84% (95% CI=99.77 - 99.89), being lower in schools with the highest attack rate, immunised with current vaccine from Jeryl Lynn strain: 71.01% (95% CI=55.85 80.97). Two doses of this strain were used in 13.79% of the cases. Susceptible populations were vaccinated at the start of the outbreak: 11,381 doses used in schools and 93 outside schools.

CONCLUSIONS

An outbreak of mumps virus G 1 population with high rates of mumps vaccine coverage, with areas with low vaccine effectiveness with current vaccine. Mass vaccination of population has contributed to the resolution of the outbreak.

Transmission of mumps virus from mumps-vaccinated individuals to close contacts

During a recent mumps epidemic in the Netherlands caused by a genotype D mumps virus strain, we investigated the potential of vaccinated people to spread mumps disease to close contacts. We compared mumps viral titers of oral fluid specimens obtained by quantitative PCR from vaccinated (n=60) and unvaccinated (n=111) mumps patients. We also investigated the occurrence of mumps infection among the household contacts of vaccinated mumps patients. We found that viral titers are higher for unvaccinated patients than for vaccinated patients during the 1st 3 days after onset of disease. While no symptomatic cases were reported among the household contacts (n=164) of vaccinated mumps patients (n=36), there were cases with serological evidence of asymptomatic infection among vaccinated household contacts (9 of 66 vaccinated siblings). For two of these siblings, the vaccinated index patient was the most probable source of infection. We conclude that, in this particular outbreak, the risk of a close contact becoming infected by vaccinated patients was small, but present.

An assessment of mumps vaccine effectiveness by dose during an outbreak in Canada

BACKGROUND

This investigation was done to assess vaccine effectiveness of one and two doses of the measles, mumps and rubella (MMR) vaccine during an outbreak of mumps in Ontario. The level of coverage required to reach herd immunity and interrupt community transmission of mumps was also estimated.

METHODS

Information on confirmed cases of mumps was retrieved from Ontario's integrated Public Health Information System. Cases that occurred between Sept. 1, 2009, and June 10, 2010, were included. Selected health units supplied coverage data from the Ontario Immunization Record Information System. Vaccine effectiveness by dose was calculated using the screening method. The basic reproductive number (R(0)) represents the average number of new infections per case in a fully susceptible population, and R(0) values of between 4 and 10 were considered for varying levels of vaccine effectiveness.

RESULTS

A total of 134 confirmed cases of mumps were identified. Information on receipt of MMR vaccine was available for 114 (85.1%) cases, of whom 63 (55.3%) reported having received only one dose of vaccine; 32 (28.1%) reported having received two doses. Vaccine effectiveness of one dose of the MMR vaccine ranged from 49.2% to 81.6%, whereas vaccine effectiveness of two doses ranged from 66.3% to 88.0%. If we assume vaccine effectiveness of 85% for two doses of the vaccine, vaccine coverage of 88.2% and 98.0% would be needed to interrupt community transmission of mumps if the corresponding reproductive values were four and six.

INTERPRETATION

Our estimates of vaccine effectiveness of one and two doses of mumps-containing vaccine were consistent with the estimates that have been reported in other outbreaks. Outbreaks occurring in Ontario and elsewhere serve as a warning against complacency over vaccination programs.

Rescue of wild-type mumps virus from a strain associated with recent outbreaks helps to define the role of the SH ORF in the pathogenesis of mumps virus

Mumps virus (MuV) causes acute infections in humans. In recent years, MuV has caused epidemics among highly vaccinated populations. The largest outbreak in the U.S. in the past 20 years occurred in 2005-2006 with over 5000 reported cases in which the majority of the cases was in vaccinated young adults. We sequenced the complete genome of a representative strain from the epidemic (MuV-IA). MuV-IA is a member of genotype G, the same genotype of MuV that was associated with the outbreak in the UK in 2004-2005. We constructed a reverse genetics system for MuV-IA (rMuV-IA), and rescued a virus lacking the open reading frame (ORF) of the SH gene (rMuV∆SH). rMuV∆SH infection in L929 cells induced increased NF-κB activation, TNF-α production and apoptosis compared to rMuV-IA. rMuV∆SH was attenuated in an animal model. These results indicated that the SH ORF of MuV plays a significant role in interfering with TNF-α signaling and viral pathogenesis during virus infection.