[Background]：In 2007-2008, measles outbreaks occurred country-wide mainly among young people in their teens and twenties. The government implemented a 5-year interim measles-rubella vaccination program to boost the immunity in the young, beginning from the 2008 fiscal year (FY, April to next yearʼs March). In the present paper, we made a seroepidemiological investigation into the effect among the vaccination target groups (third-year high school students) who were born in FY1990 to FY1994. By using the voluminous data of the antibody tests performed at a commercial diagnostic laboratory, we calculated “approximate” antibody prevalence rates (see below) for different birth cohorts, and were able to plot their yearly changes after the vaccination.
[Methods]：The rubella antibody was determined with the hemagglutination-inhibition (HI) method, and the measles IgG antibody with an enzyme immunoassay (EIA) using a commercially available kit. The antibody data mainly from healthy college students and hospital workers were used for analysis. Antibodypositive proportions among each age group in each “summation year”(see below) were calculated. In addition, age-specific geometric mean rubella HI antibody titers were calculated.
[Results]：1) Since the individual antibody data contain information on the personʼs age but not the month of birth, the antibody prevalence rate of a birth cohort in a certain year is not calculable. However,we found that, when age-specific antibody prevalence is calculated by summation of one-year data from the previous yearʼs October to September (summation year, SY), it reflects 75% of the data of the birth cohort. We then used this value as the birth cohort-specific “approximate” antibody prevalence in the one-year period. We then depicted the graphs for yearly changes in the approximate prevalence rates of each birth cohort. 2) We found that, with cutoff HI antibody titers of ≧8, the prevalence percentage for the FY1990-1994 birth cohorts (vaccination target) increased after the vaccination and remained at high levels. In contrast,the prevalence rates with cutoff HI titers of ≧32 soon decreased；this pattern of the yearly changes seemed similar to that of the changes in approximate mean antibody titers. However, the FY1980-1983 birth cohorts, who had experienced nationwide rubella epidemics in 1987, maintained relatively higher prevalence rates. We think that the latter group had stronger immune responses through natural infection. 3) We also observed the rise in the approximate measles antibody prevalence rates with cutoff EIA antibody levels of ≧4U among the vaccination target groups. However, the prevalence rates with cutoff antibody levels of ≧16U decreased soon, but the FY1980 birth cohort, who had experienced nationwide measles epidemics in 1884, retained higher prevalence rates.
[Conclusions]：The effect of the interim vaccination was seroepidemiologically confirmed, but the immune response after the vaccination was observed to be weaker than that after natural infection. In Japan where measles has been eliminated by vaccination, the immunity among the adult population will wane in the future. By utilizing the data accumulated at big commercial diagnostic laboratories, it is useful for following up the trend to observe the yearly changes in approximate antibody prevalence rates among different birth cohorts employing both low and high cutoff antibody levels.
The performance and the cross-reactivity to HIV-1 and HIV-2 between NEW LAV BLOT I and II,which are Western blot kits for HIV-1 and HIV-2, respectively, were evaluated using 89 HIV-1-positive specimens collected in Japan from 2013 to 2015 and 34 specimens in commercial anti HIV-1/2 Combo Performance Panels. HIV-1 positive specimens collected in Japan were detected almost perfectly using NEW LAV BLOT I. The true positive rate was higher based on the CDC criteria (98.9%) than on the WHO criteria (95.5%). When the same specimens were tested using NEW LAV BLOT II, 12 of them were determined to be HIV-2 positive following the criteria described in an attached manual and thus judged as “untypable”. However, all of these specimens were judged indeterminate based on the WHO criteria and thus they were not judged as ”untypable”. From the results obtained using anti HIV-1/2 Combo Performance Panels, the true positive rate of HIV-1-positive specimens tested using New LAV BLOT I was higher based on the CDC criteria (84.6%) than on the WHO criteria (46.2%). However, because 6 of 13 HIV-2-positive specimens were determined to be HIV-1 positive following the CDC criteria, these specimens became “untypable”. Considering the current HIV epidemic in Japan, we should apply NEW LAV BLOT I first to perform confirmatory tests of screening-test positive specimens. When the result is negative or indeterminate, a confirmatory test using NEW LAV BLOT II is useful the PCR findings of HIV-1 RNA are negative and the patient is at some risk of HIV-2 infection. When NEW LAV BLOT I and II are used for discrimination of HIV-1 and 2 infections in parallel, we might use the WHO criteria.
We, herein, reported a case of travelerʼs diarrhea due to extended spectrum β―lactamase (ESBL) producing Shigella sonnei returning from Cambodia. A 28-year-old female, mild diarrhea without blood appeared on the final day of traveling for 8 days. Although physical findings and blood tests were normal, ESBL producing S. sonnei was detected from stool culture, and antibiotic therapy with MEPM (1g three times a day) was performed. ESBL producing bacteria seriously spread in Enterobacteriaceae, and the transfer of ESBL production to Shigellosis is also concerned. Clinical efficacy of antibiotic therapy for infections due to ESBLproducing Shigella spp. in Japan is insufficient and current case is considered to be meaningful.
We report herein on the case of a 54-year-old Japanese male diagnosed as having Rickettsia disease based on the detection of Rickettsia japonica in the blood crust from the biopsy scar of an eschar. In late September 2016, the patient suffered from a 39℃ fever and visited a hospital. He had an eschar on the right abdomen and a rash present over the whole body. Blood tests showed thrombocytopenia, severe inflammation,and mild liver dysfunction. A real-time PCR procedure detected Rickettsia japonica DNA in the blood crust from the biopsy scar of the eschar, suggesting Japanese spotted fever. He recovered well from the disease with the administration of minocycline and ciprofloxacin. The PCR detection of R. japonica DNA in the blood crust from a biopsy scar of an eschar can be a sensitive method for the early diagnosis of Rickettsia disease.