Rickettsiae belongs to the order Rickettsiales, whose members were described as obligate intracellular gramnegative microorganisms. Several species cause diseases in humans and other vertebrate or invertebrate hosts, and have a worldwide distribution. For the last 15 years, nine new rickettsiosis have been reported, that is, Japanese spotted fever caused by Rickettsia japonica (19,39), Flinders Island spotted fever caused by R. honei (33,34), Astrakhan tick bite fever caused by Astrakhan fever rickettsia (5), African tick bite fever caused by R. africae (15), California flea typhus caused by R. felis (the ELB agent) (35), and four other unnamed spotted fevers caused by R. mongolotimonae (30,44), R. slovaca (18, 31, 36), R. helvetica (11, 25), and "R. heilongjiangii," (17, 45) respectively. In Japan, 63 tick-associated rickettsiae strains, belonging to at least three serotypes, have been isolated over the last several years (8-10), including R. japonica isolated from the Dermacentor taiwanensis and Haemaphysalis frava ticks, respectively; R. helvetica (strains IP-1 and IM-1), strains Abstract: In order to understand the natural situation of rickettsiae in the ticks in Japan, the rickettsial genes, gltA gene, rOmpA gene, and 17-kDa gene, were amplified from the ticks by nested PCR. The prevalences of rickettsial gltA genes among Haemaphysalis formosensis, H. longicornis, H. megaspinosa, Ixodes ovatus, H. flava, H. kitaokai, and I. persulcatus were 62, 57, 24, 24, 19, 13, and 10%, respectively; 26% (186/722) being the average. The gltA genes amplified from the ticks were classified into 9 genotypes (I to IX) by the difference in nucleotide sequences. Genotype I was detected from 7 species of ticks. Genotype II mainly was detected from H. longicornis and H. formosensis. Genotypes III and VII mainly were detected from H. flava and I. ovatus. The polarization in the distribution of genotypes among regions where the ticks were collected was not clear. Based on the phylogenetic analysis of the three genes presented here, genotypes I, III, and IV (detected from H. formosensis, H. hystricia, and I. ovatus) are genetically close with each other, but rickettsiae of the same property still have not been isolated from ticks anywhere in the world. These genotypes should be considered as new species among SFG rickettsiae. Genotype II was identical with strain FUJ-98, genetically close to R. japonica which has been isolated from ticks in China. Genotype V was identical with R. felis and strain California 2 isolated from the cat flea. This is the first report on the detection of R. felis from ticks. Genotype VI detected from Ixodes sp. did not seem to belong to genus Rickettsia. Based on the previous antigenic data and the phylogenetic analysis presented here, Genotype VII should be considered a variant of R. helvetica and genotype VIII detected from I. ovatus and I. persulcatus were identical with R. helvetica. Genotype IX detected from I. nipponensis was genetically close to the strains IRS3, IRS4, and IrR/Munich isolated from...

Various genotypes of norovirus (NoV) (genogroup I genotype 1 [GI.1], -2, -4, -5, -8, -11, -12, and -14; GII.3, -4, -6, -7, -10, -13, -14, and -15), and sapovirus (SaV) (GI.1 and GI.2, GII.1, and GIV.1) were detected from raw sewage from April 2006 to March 2008, while limited numbers of genotypes of NoV (GI.8, GII.4, GII.6, and GII.13) and SaV (GII.3 and GIV.1) and of NoV (GII.4, GII.7, and GII.13) were detected from clinical cases and healthy children, respectively. During the winter 2006 to 2008, a large number of sporadic gastroenteritis outbreaks and many outbreaks caused by NoV GII.4 occurred among inhabitants in Toyama, Japan. The copy number of genomes of NoV GII detected from raw sewage changed in relation to the number of outbreaks. NoV strains of the same genotypes observed in both raw sewage and human specimens belonged to the same cluster by phylogenetic analysis and had almost identical nucleotide sequences among each genotype. These data suggest that NoVs and SaVs detected from raw sewage reflect the viruses circulating in the community, irrespective of symptoms, and that subclinical infections of NoV are common in Japan. Combined surveys of raw sewage with those of clinical cases help us to understand the relationship between infection of these viruses and gastroenteritis.

A molecular biological survey on porcine norovirus (NoV) and sapovirus (SaV) was conducted in Toyama Prefecture, Japan, during fiscal year 2008. Both NoV and SaV were detected from swine fecal samples throughout the surveillance period, indicating that these viruses were circulating in this region. NoV strains detected in this study belonged to three genotypes that are known as typical swine NoVs. Although human NoVs were occasionally detected, it was unclear whether they replicated in pigs. As for SaV, genogroup VII (GVII) and other divergent genogroups were identified in addition to the dominant genogroup, GIII, which is the prototypic porcine SaV. In addition, 3 strains genetically related to human SaV were detected. Two of these 3 strains were closely related to human SaV GV. Our study showed that genetic diversification of porcine SaV is currently progressing in the swine population.

Seventy-eight poliovirus strains isolated from river water and sewage in Toyama Prefecture, Japan, during 1993 to 1995 were characterized by the PCR-restriction fragment length polymorphism (RFLP) method and by partially sequencing the VP3 and VP1 regions of the viral genome. Of these isolates, 36 were identified as Sabin vaccine strains, and 42 were identified as vaccine variant strains that had less than 1.4% nucleotide divergence from the Sabin strains, including 7 isolates with patterns different from those of Sabin strains as determined by PCR-RFLP analysis. These findings suggest that wild-type poliovirus was not circulating in Toyama Prefecture.

Fecal specimens from patients with acute diarrhea were collected from 10 prefectures in Japan over a 6-month period (November 1992 to April 1993), and the specimens that were negative for human group A rotaviruses were screened for the presence of human group C rotaviruses (CHRVs) by the reverse passive hemagglutination test. Of 784 specimens examined, 53 samples (6.8%) that were collected in 7 of 10 prefectures were positive for CHRV, indicating that CHRVs are widely distributed across Japan. Most of the CHRV isolates were detected in March and April, and CHRVs mainly prevailed in children ages 3 to 8 years. The genome electropherotypes of eight strains isolated in five individual prefectures were surprisingly similar to each other and were different from those of CHRV strains isolated to date. The outer capsid glycoprotein (VP7) gene homologies of the isolates retrieved in 1993 were subsequently analyzed by the dot blot hybridization method. As a result, the VP7 genes of the isolates revealed very high levels of homology not only with each other but also with the VP7 gene of the OK118 strain isolated in 1988. These results suggest that a large-scale outbreak of CHRV occurred during the winter of 1992 and 1993 in Japan.