【Background】The immune status of the people to rubella is affected both by vaccination policies and nationwide epidemics. In Japan, mass rubella vaccination was started in 1977 to junior-high school girls. Measles-Mumps-Rubella (MMR) vaccination to young children was carried out from April 1989 to April 1993. In 1995, regular rubella vaccination to children was started together with interim individual vaccination to 12- to 15-year-olds of both sexes for 6.5 years. Meanwhile, nationwide rubella epidemics broke out mainly at primary schools in five times：1965-1968, 1976-1977, 1982, 1987-1988, and 1992-1993.In this study, we used rubella antibody data generated at a big diagnostic laboratory to which specimens gather from all over Japan,and investigated whether the results explain the history of changes in the vaccination policies and the natural epidemics in Japan.
【Methods】A total of 672,531 data (male 87,429 and female 585,102) on rubella hemagglutination inhibiting (HI) antibody titers were used for analysis. The data were from the sera with no specific clinical department names (which may contain specimens from healthy individuals for determining rubella immune status). The serum specimens were collected from 19- to 60-year-olds during an eight-year period of October 2010 to September 2018. The “approximate” antibody prevalence rates and mean antibody titers of eight consecutive age groups of each birth cohort of Japanese fiscal year (FY：April to next yearʼs March), were calculated according to F. Ban et al (J Japan Assoc Infect Dis. 2019；93：1-11).
【Results】We depicted graphs both for the antibody prevalence rates and mean antibody titers by birth cohort and age, using 5-age moving averages. From these graphs the following findings were obtained. 1) Mass vaccination to junior-high school girls：The antibody prevalence rose from the FY1961 birth cohorts (about 90%) to the vaccinated FY1993 birth cohorts (about 95%). 2) Individual vaccination to male teens：The antibody prevalence increased to about 85% in the FY1980 birth cohorts and reached about 90% in the FY1982 birth cohort. 3）Effects of nationwide epidemics：The mean antibody titers of the FY1985 birth cohorts who experienced the last nationwide epidemics at primary schools in 1992-1993 were about 2 5.4 , but those of the FY1988 birth cohorts who had received MMR vaccination but not experienced the epidemic were about 2 4.7 .
【Conclusions】We think that the analysis of the data from the commercial diagnostic laboratory explains well the rubella epidemiology during the past 60 years in Japan, and is useful for the future rubella control policies for the country.
In Japan, respiratory syncytial virus (RSV) infection is seasonal with epidemics occurring between late autumn and winter. Recently, however, epidemics have tended to start during summer and autumn. To evaluate the change of the clinical features of infants who were infected in summer (summer epidemic group) and other seasons (non-summer epidemic group) the medical records were retrospectively reviewed of Japanese infants who were hospitalized in our institution between June 2014 to May 2019 due to poor general condition with a positive RSV rapid test. The summer epidemic group included 126 infants who had the rapid test between June to September and the non-summer epidemic group included 245 infants who had the test between October to April. The summer epidemic group showed a higher rate of infants with positive bronchial asthma predictive index and infants with wheezing. However, the ratio of infants with respiratory failure was similar in both groups. In conclusion, RSV infected infants in summer may be related to the diagnostic feature of bronchial asthma.
To understand the risk of methicillin-resistant Staphylococcus aureus (MRSA) infection that occurs from contaminated food, we investigated the prevalence of MRSA in retail meat and seafood and analyzed the antimicrobial susceptibility and genotypes of the isolates. MRSA was identified in 21 out of 270 food samples (158 domestic samples and 112 imported samples) of food sold in Tokyo in 2017. The 22 MRSA isolates from the 21 food samples were all susceptible to vancomycin, teicoplanin, linezolid, and trimethoprim sulfamethoxazole, but resistant to minocycline (3 isolates), fluoroquinolone (7 isolates), amikacin (3 isolates),gentamicin (8 isolates), and kanamycin (9 isolates). The genotypes of 7 isolates from imported pork samples were CC398 and SCCmec V, which are livestock-associated MRSA isolates reported in the United States and Europe. The 7 isolates exhibited resistance to tetracycline and resistance or intermediate resistance to minocycline and possessed tetK and tetM. The genotypes of 7 isolates from domestic meat samples were CC8 and SCCmec IV, which are community-acquired MRSA isolates reported in Japan. However, SCCmec II isolates,which are reported frequently in healthcare-acquired MRSA, were not isolated in the present study. The genotypes of isolates varied between domestic and imported samples. The results suggest that there is a risk of MRSA infection from food sources.
Leptospirosis is a zoonotic disease common in tropical and subtropical regions caused by pathogenic Leptospira species. Presented herein is a case of leptospirosis in a 37-year-old man which was effectively diagnosed in cerebrospinal fluid (CSF) with the polymerase chain reaction（PCR）technique. Fourteen days prior to admission, the patient had cleaned his basement which had been flooded out by a typhoon. Six days before admission, he developed a fever, headache, and myalgia. On admission day (6th day of illness), he presented to our hospital complaining of general malaise and myalgia that was so severe he was unable to walk by himself. A clinical diagnosis of leptospirosis was made based on his history of exposure to contaminated water and conjunctival suffusion on examination. After hospitalization, he was given a 7-day course of doxycycline with rapid improvement of his symptoms, and was discharged on the 12th day of illness. A flaB gene of Leptospira was detected in his CSF with PCR on the admission day. Antibody titers to Leptospira interrogans serovar Hebdomadis, L. interrogans serovar Kremastos, and Leptospira borgpetersenii serovar Poi were elevated in the microscopic agglutination test of the convalescent serum on the 24th day of illness. The clinical presentation of leptospirosis is biphasic with an acute phase and a convalescent phase. Localization of leptospiras changes depend upon the different phase of the illness. Leptospira is present in the blood from the early―to mid-acute phase, in the CSF from the mid-acute to convalescent phase, and in the urine from the late-acute to convalescent phase. Submitting specimens tailored by the clinical phase of leptospirosis may be useful for diagnosis.