[An Epidemiological Study on an Influenza Outbreak at Day Nurseries and Nursing Institutions in Gunma].

OBJECTIVE: The features of influenza outbreaks (IOs) at day nurseries (DN), facilities for the handicapped (FH), and care homes for the elderly (CHE) are unclear. The aim of this study was to clarify these features at each institution. MATERIALS AND METHODS: The authors examined IOs (n = 258) that occurred at DN, FH, or CHE in Gunma Prefecture between 2012 and 2014, and the characteristics of such IOs were investigated epidemiologically. Results : (1) DN had a higher number of users, a higher user-to-staff member ratio, and a lower number of staff members compared to those at FH. and CHE. (2) The rate of IOs was highest at DN. (3) At DN and CHE, the occurrence of IOs during the early period of the influenza season in the community was higher than that during the late period of the influenza season in the community. (4) IOs persisted for longer at DN. (5) The IOs attack rates were highest at FH during the early, late, and total periods, although those at FH and CHE decreased slightly during the late period. (6) The attack rates of staff members at CHE during the early period and at FH during the late period were high. The attack rate of staff members at CHE significantly decreased during the late period. CONCLUSIONS: The occurrence of IOs at DN and CHE will be influenced by influenza epidemicity seen outside of the institutions. IOs often occurred and were prolonged at DN, which can be explained by the high rate and frequency of secondary infection resulting from the very close contact among users. At CHE, the attack rate increased due to the very close contact between users and staff members, especially during the early period; however, the attack rate at CHE during the late period decreased due to the prevention of secondary infection. At FH, the attack rates were higher compared to those at DN and FH, which was influenced by the high degree of contact among users and between users and staff members. The spread and prolongation of IOs will be influenced by the users',high degree of behavior, the high degree of contact between users, and the high degree of contact among users and between users and staff members. Prevention of IOs and their prolongation and spread should be conducted according to factors that affect the duration and spread of IOs, as described above.

[The importance of using a test to detect Chlamydia trachomatis infection in patients undergoing counseling and testing for sexually transmitted diseases at a public health center].

OBJECTIVES: Serum levels of antibody against Chlamydia trachomatis are used routinely to diagnose chlamydial infection among patients undergoing counseling and testing for sexually transmitted disease at public health centers in Japan, whereas tests for pathogen detection are conducted at most clinics. The objective of the present study was to evaluate the usefulness of a test for detecting C. trachomatis and to compare it with that of screening for serum chlamydia antibodies at a public health center. METHODS: Serum chlamydia antibody titers were estimated using an ELISA, while C. trachomatis was detected in the urine using the nucleic acid amplification assay that included strand displacement amplification (SDA). We compared the results of 120 patients (64 men and 56 women), because the sensitivity of the method using urine samples from women has been reported to be as high as that using cervical samples. The serum antibody test results were considered to be positive when either one or both of the IgA and IgG antibodies were positive. RESULTS: The overall prevalence of positive results for the antibody test was 24.2% (14.1% for men and 35.7% for women), and that for the SDA method was 7.5% (3.1% for men and 12.5% for women). The concordance rate of the 2 tests was 81.7%, with a kappa statistic of 0.35 (95% CI, 0.10-0.59). Of the 9 subjects who were positive for C. trachomatis using the SDA assay, 1 had serum chlamydia IgA antibodies, 6 had IgG antibodies, 1 had both the antibodies, and 1 had no antibodies. On the other hand, of the 111 subjects who were negative for C. trachomatis, only 8 had chlamydia IgA antibodies, 5 had IgG antibodies, and 8 had both the antibodies. These results indicated there was no association between serum IgA antibodies and the presence of C. trachomatis. The presence of serum chlamydia antibodies was significantly higher in subjects with a past history of genital chlamydial infection than in those without a past history of infection (P<0.01). However, there was no difference in the results of the SDA assay between subjects with or without a previous infection. CONCLUSION: Thus, although serum chlamydia antibodies are generally measured at public health centers, tests for detecting C. trachomatis should also be used.

Case-Based Surveillance of Pandemic (H1N1) 2009 in Maebashi City, Japan.

After national case-based surveillance for pandemic influenza A (H1N1) ceased on July 23, 2009, a daily case-based surveillance system was implemented in Maebashi City, Japan. All medical facilities in the city reported all patients who had positive rapid antigen tests for influenza A. When the epidemic exploded in late October, case-based surveillance for influenza-like illness (ILI) was implemented from November 3, 2009 until the end of the epidemic. A total of 7,781 influenza cases were reported between July 25 and November 2, 2009, with a cumulative incidence rate of 22.5 per 1,000 population. Nearly 70% of the patients were under 15 years old. Between November 3, 2009 and the end of March 2010, a total of 16,394 ILI cases were reported, with a cumulative incidence rate of 47.4 per 1,000 population. Of the ILI cases reported, 63% were in patients younger than 15 years old. Only one death with laboratory confirmation of the H1N1 2009 virus was reported during the epidemic. The age-specific reproduction number among children under 15 years of age was almost 1.40, whereas between children and adults (15 years of age and above) it was considerably less than 1.0. The reproduction number derived from the next-generation matrix using data from September 30 to October 14 was estimated to be 1.48 (95% confidence interval, 1.41-1.56). Among individuals under 15 years of age, the infection rate calculated using the final size equation under the assumption of no mitigation measures was nearly twice the rate reported during the epidemic. These findings indicate that the majority of the transmission of influenza A (H1N1) 2009 in the city occurred among children.

[Vaccination coverage of foreign children and their parents' views on immunization services in Gunma Prefecture, Japan].

OBJECTIVES: The aim was to evaluate vaccination coverage among foreign children living in an urban area of Gunma Prefecture, Japan and to examine their parents' views concerning the local immunization services. METHODS: A total of 321 foreign children aged 6 to 18 years in five international schools participated in school health examinations and provided vaccination information. Among the parents, 304 completed a questionnaire on their views about the immunization services. Another questionnaire survey was conducted in nursery schools for parents of 4629 Japanese children aged 0 to 6 years. Of the total, 3811 (82.3%) responded, and 2911 questionnaires answered by the parents who had children aged 3 years and older were eligible for the analysis. RESULTS: The study found a vaccination coverage of 86.2% for diphtheria and tetanus toxoids and pertussis (DTP), 86.5% for poliovirus vaccine, and 87.7% for BCG among the foreign children. Of their parents, 84% were born in Brazil. One third of the foreign children vaccinated for DTP, poliovirus and/or BCG had received each vaccine in Japan, while the others children had been vaccinated in their home countries. Among 162 parents with children immunized in Japan, 77% received the necessary information about immunization services from the local municipal office, and 80% had no major problems. However, 15% felt the language barrier. Among the Japanese children, non-vaccination rates for DTP, poliovirus vaccine, and BCG were 18.5%, 9.9%, and 3.5%, respectively. Of the Japanese parents, 85% knew immunization schedules from the municipal office, and 51% asked for night-time and holiday vaccination sites. CONCLUSION: These results suggest that vaccination coverage for DTP, poliovirus vaccine or BCG is relatively high among foreign children living in Japan. To promote higher rates of vaccination for those residents, however, accessibility of the municipal consultation services in foreign languages should be im-proved.