Search

Rickettsiae are obligate intracellular bacteria that have small genomes as a result of reductive evolution. Many Rickettsia species of the spotted fever group (SFG) cause tick-borne diseases known as "spotted fevers". The life cycle of SFG rickettsiae is closely associated with that of the tick, which is generally thought to act as a bacterial vector and reservoir that maintains the bacterium through transstadial and transovarial transmission. Each SFG member is thought to have adapted to a specific tick species, thus restricting the bacterial distribution to a relatively limited geographic region. These unique features of SFG rickettsiae allow investigation of how the genomes of such biologically and ecologically specialized bacteria evolve after genome reduction and the types of population structures that are generated. Here, we performed a nationwide, high-resolution phylogenetic analysis of Rickettsia japonica, an etiological agent of Japanese spotted fever that is distributed in Japan and Korea. The comparison of complete or nearly complete sequences obtained from 31 R. japonica strains isolated from various sources in Japan over the past 30 years demonstrated an extremely low level of genomic diversity. In particular, only 34 single nucleotide polymorphisms were identified among the 27 strains of the major lineage containing all clinical isolates and tick isolates from the three tick species. Our data provide novel insights into the biology and genome evolution of R. japonica, including the possibilities of recent clonal expansion and a long generation time in nature due to the long dormant phase associated with tick life cycles.

Tsutsugamushi disease and Japanese spotted fever are representative rickettsioses in Japan, and are caused by infection with Orientia tsutsugamushi and Rickettsia japonica, respectively. For molecular-based diagnosis, conventional PCR assays, which independently amplify respective rickettsial DNA, are usually used; however, this approach is time-consuming. Here, we describe a new duplex real-time PCR assay for the simultaneous detection of O. tsutsugamushi and spotted fever group rickettsiae, and its evaluation using several PCR conditions in 6 public health laboratories. The detection limit of the assay was estimated to be 102 copies and the sensitivity was almost identical to that of 3 conventional PCR methods. A total of 317 febrile patients were selected as clinically suspected or confirmed cases of rickettsioses. The detection efficiency of this assay for O. tsutsugamushi from blood or skin (eschar) specimens appeared to be almost the same as that of the conventional PCR method, even when performed in different laboratories, whereas the efficiency for spotted fever group rickettsiae tended to be higher than that of the 2 traditional double PCR assays. Our duplex real-time PCR is thus a powerful tool for the rapid diagnosis of rickettsioses, especially at the acute stage of infection.

Background Severe fever with thrombocytopenia syndrome (SFTS) is a tick-borne acute infectious disease caused by the SFTS virus (SFTSV). SFTS has been reported in China, South Korea, and Japan as a novel Bunyavirus. Although several molecular epidemiology and phylogenetic studies have been performed, the information obtained was limited, because the analyses included no or only a small number of SFTSV strains from Japan. Methods The nucleotide sequences of 75 SFTSV samples in Japan were newly determined directly from the patients' serum samples. In addition, the sequences of 7 strains isolated in vitro were determined and compared with those in the patients' serum samples. More than 90 strains that were identified in China, 1 strain in South Korea, and 50 strains in Japan were phylogenetically analyzed. Results The viruses were clustered into 2 clades, which were consistent with the geographic distribution. Three strains identified in Japan were clustered in the Chinese clade, and 4 strains identified in China and 26 in South Korea were clustered in the Japanese clade. Conclusions Two clades of SFTSV may have evolved separately over time. On rare occasions, the viruses were transmitted overseas to the region in which viruses of the other clade were prevalent.

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease with a high case fatality risk and is caused by the SFTS virus (SFTSV). A retrospective study conducted after the first identification of an SFTS patient in Japan revealed that SFTS is endemic to the region, and the virus exists indigenously in Japan. Since the nucleotide sequence of Japanese SFTSV strains contains considerable differences compared with that of Chinese strains, there is an urgent need to establish a sensitive and specific method capable of detecting the Chinese and Japanese strains of SFTSV. A conventional one-step reverse transcription-PCR (RT-PCR) (cvPCR) method and a quantitative one-step RT-PCR (qPCR) method were developed to detect the SFTSV genome. Both cvPCR and qPCR detected a Chinese SFTSV strain. Forty-one of 108 Japanese patients suspected of having SFTS showed a positive reaction by cvPCR. The results from the samples of 108 Japanese patients determined by the qPCR method were in almost complete agreement with those determined by cvPCR. The analyses of the viral copy number level in the patient blood samples at the acute phase determined by qPCR in association with the patient outcome confirmed that the SFTSV RNA load in the blood of the nonsurviving patients was significantly higher than that of the surviving patients. Therefore, the cvPCR and qPCR methods developed in this study can provide a powerful means for diagnosing SFTS. In addition, the detection of the SFTSV genome level by qPCR in the blood of the patients at the acute phase may serve as an indicator to predict the outcome of SFTS.

We have studied the prevalence of the subgenus F adenoviruses and the molecular characteristics of adenovirus type 41 in Hiroshima Prefecture, Japan, as a limited area during the period of 1997–2004. Subgenus F adenoviruses were detected in 30 (3.4%) of 892 fecal specimens by enzyme immunoassay (EIA), and 80.0% (24 of 30) of positive patients were

The aim of this study was to investigate the safety and long-term effects on serum lipid levels of low-dose simvastatin, an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, in Japanese patients with moderate primary hypercholesterolemia. We assigned 201 patients (68 men and 133 women; mean +/- SD age, 61.3 +/- 10.2 years) with serum total cholesterol levelsor = 220 mg/dL to receive simvastatin 5 mg each evening; the treatment period was 1 year. Serum total cholesterol, triglycerides, and low-density lipoprotein (LDL) cholesterol levels decreased significantly in response to simvastatin therapy, and the changes were maintained throughout the treatment period. Mean total cholesterol decreased from 269.9 +/- 35.4 mg/dL to 215.2 +/- 34.5 mg/dL (20.3%), triglycerides decreased from 183.0 +/- 110.2 mg/dL to 155.5 +/- 88.5 mg/dL (15.0%), and LDL cholesterol decreased from 180.0 +/- 33.1 mg/dL to 130.1 +/- 35.1 mg/dL (27.7%). Total cholesterol, triglycerides, and LDL cholesterol tended to decline when the pretreatment values were higher; the critical values and the bidirectional changes of the serum lipid levels were 188.1, 109.5, and 91.6 mg/dL, respectively. Although the serum level of high-density lipoprotein cholesterol did not change significantly, it tended to increase more when the pretreatment values were lower; the "critical value" was 70 mg/dL. Nine patients experienced mild adverse events, but none discontinued simvastatin during the 12-month treatment period. We found that low-dose simvastatin therapy is effective in achieving long-term decreases in serum lipid levels and is well tolerated by patients with moderate hypercholesterolemia. Simvastatin therapy may result in normalization of serum lipid levels.

In order to determine what factors are related to falls and the effect on the aged, a study was conducted on subjects aged 60 years and over who had undergone preventive health examinations in the western region of Shizuoka Prefecture. Subjects (n = 305) had an average age of 64.4 +/- 3.8 years, and all were interviewed regardless of their history of falls. For the 66 cases who had experienced falls, further questions prepared in advance, were included. The following results were obtained: 1) There were 66 subjects (21.6% of the subjects) who had experienced falls with some experienced multiple falls for a total count of 91 falls. 2) The frequency of falls of female subjects was significantly higher than that of males. Further, with respect to the type of injuries suffered, in the case of many of the female subjects, these took the form of contusions. 3) The majority of subjects who experienced falls were engaged in farming and most of the falls were work-related. 4) Results of this study showed that, while not statistically significant, cerebrovascular diseases are closely connected to falls and increases the falls coefficient among the aged.