Incidence of Mumps Deafness in Japan, 2005-2017: Analysis of Japanese Insurance Claims Database.

BACKGROUND: Mumps deafness causes serious problems, and incidence data are needed to identify its disease burden. However, such data are limited, and the reported incidence is highly variable. Nationwide studies in Japan with a large age range are lacking. METHODS: This was a retrospective observational investigation of the 2005-2017 mumps burden using employment-based health insurance claims data. Data were analyzed for 5,190,326 people aged 0-64 years to estimate the incidence of mumps deafness. RESULTS: Of 68,112 patients with mumps (36,423 males; 31,689 females), 102 (48 males; 54 females) developed mumps deafness-an incidence of 15.0 per 10,000 patients (1 in 668 patients). Fifty-four (52.9%) patients had mumps deafness in childhood (0-15 years), and 48 (47.1%) had mumps deafness in adolescence and adulthood (16-64 years); most cases occurred in childhood, the peak period for mumps onset. The incidence of mumps deafness per 10,000 patients was 73.6 in adolescence and adulthood, 8.4 times higher than the incidence of 8.8 in childhood (P < 0.001). In childhood, the incidence of mumps deafness was 7.2 times higher among 6-15-year-olds (13.8; 95% CI, 10.2-18.2) than among 0-5-year-olds (1.9; 95% CI, 0.6-4.5), and this difference was statistically significant (P < 0.001). No sex difference was observed. CONCLUSIONS: The incidence of mumps deafness per 10,000 patients aged 0-64 years was 15.0 (1 in 668 patients). A secondary risk of deafness following mumps virus infection was identified not only for children, but also for adolescents and adults.

Mumps-Related Disease Burden in Japan: Analysis of JMDC Health Insurance Reimbursement Data for 2005-2017.

BACKGROUND: Mumps vaccination coverage is low in Japan, partly because of its voluntary nature. Although pediatric cases of mumps virus infection are captured by the National Epidemiological Surveillance of Infectious Diseases program under the Infectious Disease Law, there are currently no data regarding the occurrence of mumps and its complications in adults. METHODS: We investigated the annual incidence rates of mumps and its complications based on health insurance reimbursement data for 5,209,660 individuals aged 0-64 years for 2005-2017, obtained from JMDC Inc., to estimate the mumps-related disease burden during this period. RESULTS: There were three mumps outbreaks (2006, 2010, and 2016) during 2005-2017. The annual incidence of mumps was highest in individuals aged 0-5 years (808-3,792 per 100,000 persons), followed by those aged 6-15 years (658-2,141 per 100,000 persons). The incidence of mumps was higher in females than in males (male/female ratio, 0.90). Among mumps-related complications, the overall incidence (per 1,000 mumps cases) was highest for orchitis (6.6), followed by meningitis (5.8), deafness (1.3), pancreatitis (0.5), and encephalitis (0.3). No cases of oophoritis were noted. The overall incidence of mumps-related complications was 2.5 times higher in males than in females. CONCLUSIONS: This study revealed the disease burden due to mumps and its complications in Japan during 2005-2017. These data suggest the need for mumps-prevention measures in adolescents and adults, as well as in children.

[Relationship between Echovirus Epidemics and Incidence of Aseptic Meningitis following Mumps Vaccination Based on Previous Japanese Reports: Possibility of Misclassification of Echovirus Infection in Previous Reports].

OBJECTIVES: In Japan, the vaccination for mumps has been on a voluntary basis since 1993 because of safety concerns arising from the high incidence of aseptic meningitis associated with Japanese mumps vaccine strains. However, recent reports on the voluntary mumps vaccination have described the decreased incidence of postvaccination aseptic meningitis for unknown reasons. To explore the underlying reason for this decrease, we analyzed the influence of echoviruses, the most common causative viruses for community-acquired aseptic meningitis, on the previously reported incidence of aseptic meningitis following mumps vaccination. METHODS: We used available data on the yearly number of cases of echovirus detection from the Infectious Agents Surveillance Reports issued by the National Institute of Infectious Diseases as well as previously reported nationwide data on the incidence of postvaccination aseptic meningitis. RESULTS: The incidence of postvaccination aseptic meningitis tended to be higher during the period of an echovirus epidemic and lower during the period without such as epidemic. CONCLUSIONS: The present ecological trend analysis suggests the influence of echovirus epidemics on the previous reported incidence of aseptic meningitis following mumps vaccination. It is necessary to carry out a differential diagnosis of echovirus infection to identify the true causative viruses in aseptic meningitis following mumps vaccination.

Effects of a Public Subsidy Program for Mumps Vaccine on Reducing the Disease Burden in Nagoya City, Japan.

Nagoya City initiated a public subsidy program for mumps vaccination using either the Torii or Hoshino strains in August 2010. To determine the effects of the program, we used publicly available information from Nagoya City to investigate the changes in immunization rates and numbers of patients who developed post-immunization adverse reactions, including post-vaccinal aseptic meningitis, in the 7 years since its initiation. We also investigated the numbers of mumps patients reported by sentinel sites in a national database during this period. The immunization rate in one-year-old children increased from 24.3% before the program to 91.0% after 7 years. The mean numbers of reported mumps cases per sentinel site in one-year-old to preschool children-the age groups targeted by the program- were 12.9 in the 7 years before the program and 4.93 in the 7 years after initiation of the program, showing a significant decrease of 1/2.6 (p = 0.01). The number of vaccinations during the 6.5-year period was 140,316, with only one case of aseptic meningitis reported (0.7 cases/100,000 vaccinations). No other serious adverse reactions were observed. The present findings demonstrate that the public subsidy program in Nagoya City is an effective and safe measure against mumps in children.

An inverse correlation of VZV skin-test reaction, but not antibody, with severity of herpes zoster skin symptoms and zoster-associated pain.

BACKGROUND: Cell-mediated immunity (CMI) has been considered to be related to the development of herpes zoster (HZ). However, there have been no large-scale prospective studies on the relationship between VZV-specific CMI and severity of HZ. OBJECTIVE: We carried out a large-scale prospective cohort study to clarify the relationship between immunological factors for varicella-zoster virus (VZV) and the clinical severity of HZ. METHODS: We carried out a cohort study on VZV immunity in a population living on an island cluster, Shozu County in Japan, and examined the people who developed HZ during a median follow-up period of 2 years, with a focus on the relationship between cell-mediated and humoral immunity and the severity of skin lesions and zoster-associated pain. A total of 12,522 people over the age of 50 were enrolled in this study, and 258 registrants were diagnosed as HZ. CMI was measured by VZV skin test, and humoral immunity was assessed with serological tests (neutralization test, immunoadherence hemagglutination test, and gpELISA test) for VZV-specific antibodies. RESULTS: CMI to VZV assessed by VZV skin test showed a significant inverse relationship to the severity of HZ skin lesions, and also to the severity of acute and subacute pain. Furthermore, weak response to the VZV skin test was associated with a high risk of post-herpetic neuralgia. In contrast, VZV-specific antibody titer was not associated with the severity of skin lesions and zoster-associated pain. CONCLUSION: VZV-specific CMI, but not humoral immunity, may play a key role in controlling the severity of HZ skin lesions and zoster-associated pain.

The Shozu Herpes Zoster (SHEZ) study: rationale, design, and description of a prospective cohort study.

BACKGROUND: The incidence and risk factors for herpes zoster have been studied in cross-sectional and cohort studies, although most such studies have been conducted in Western countries. Evidence from Asian populations is limited, and no cohort study has been conducted in Asia. We are conducting a 3-year prospective cohort study in Shozu County in Kagawa Prefecture, Japan to determine the incidence and predictive and immunologic factors for herpes zoster among Japanese. METHODS: The participants are followed for 3 years, and a telephone survey is conducted every 4 weeks. The participants were assigned to 1 of 3 studies. Participants in study A gave information on past history of herpes zoster and completed health questionnaires. Study B participants additionally underwent varicella-zoster virus (VZV) skin testing, and study C participants additionally underwent blood testing. If the participants develop herpes zoster, we evaluate clinical symptoms, measure cell-mediated immunity and humoral immunity using venous blood sampling, photograph skin areas with rash, conduct virus identification testing by polymerase chain reaction (PCR) and virus isolation from crust sampling, and evaluate postherpetic pain. RESULTS: We recruited 12 522 participants aged 50 years or older in Shozu County from December 2009 through November 2010. The participation rate was 65.7% of the target population. CONCLUSIONS: The present study is likely to provide valuable data on the incidence and predictive and immunologic factors for herpes zoster in a defined community-based population of Japanese.