[Occurrence of Tsutsugamushi disease infection by Orientia tsutsugamushi, Kawasaki serotype, in Yamagata Prefecture, Japan].

Of 95 Tsutsugamushi disease case occurring in Yamagata prefecture from 1999 to 2006, four-all women-involved the O. tsutsugamushi Kawasaki serotype. The three major symptoms were fever, exanthema, and eschar present from mid-October to early November. Serodiagnosis by indirect immunofluoresence assay showed elevated IgG and IgM antibody titers against the Kawasaki serotype antigen, with IgM higher than IgG. Nested PCR detected 56-kDa DNA in three of the cases. DNA was amplified in Kawasaki-specific PCR. Two cases for which sequencing was done using nested PCR-amplified DNA showed an identity of 99.8% for the Kawasaki strain (Accession number: M63383). These results confirmed the occurrence of Tsutsugamushi disease infection involving Kawasaki serotype in Yamagata prefecture.

Prolonged norovirus shedding in infants

BACKGROUND: Noroviruses (NV) are one of the leading causes of gastroenteritis in young children; however, the duration of NV shedding in young children is not well known. METHODS: Fecal specimens were collected from children with acute gastroenteritis at a pediatric clinic during the period from November to December 2002 and tested for NV by reverse transcription-polymerase chain reaction. RESULTS: Of 71 children infected with NV, 60 (84.5%) were less than 3 years old. Among children aged <2 years and those aged 2 to 5 years, the duration of illness was longer (7 days versus 3.5 days, P = 0.0069), the maximum number of stools in a 24-hour period was greater (7 versus 3, P = 0.0078) and a 20-point severity score was higher (11 versus 8, P = 0.0031) in patients aged <2 years than in patients aged 2 to 5 years. Among the 23 children whose follow-up specimens were obtained, the median duration of NV shedding was 16 days (range, 5-47 days). Virus shedding for more than 2 weeks after onset was observed in 75% (6 of 8), 71.4% (5 of 7) and 25% (2 of 8) of children aged <1 year, 1 year and 2 to 3 years, respectively. Three infants aged

[Nosocomial infection caused by multidrug-resistant Staphylococcus aureus with reduced susceptibility to vancomycin and teicoplanin.--Yamagata Prefecture, Japan; May 2004-Jun 2005].

Nosocomial infection caused by methicillin-resistant Staphylococcus aureus (MRSA) occurred at a major in Yamagata prefecture hospital between May 2004 and June 2005. We studied pulsed-field gel electrophoresis patterns, antimicrobial susceptibility patterns, and bacteriological features, such as coaglase type for eight isolates, including two of methicillin-resistant Staphylococcus epidermidis (MRSE). Our results suggest that this case was caused by a single strain of multidrug-resistant S. aureus. These 8 clinical isolates indicated reduced susceptibility to vancomycin and teicoplanin. PCR assay results for detection of the staphylococcal vanA, vanB, and vanC gene were all negative as all isolates. In transmission electron microscopy, cell walls appeared thicker than those of a susceptible strain from food poisoning. MRSA with reduced susceptibility to glycopeptide antibiotics may not be treated successfully with vancomycin or teicoplanin, making it important to closely observe MRSA with reduced susceptibility to glycopeptide antibiotics.

An outbreak of measles virus infection due to a genotype D9 at a junior high school in Yamagata, Japan in 2004.

We investigated a measles virus (MV) outbreak that occurred at a junior high school in Yamagata, Japan between January and February, 2004. We received throat swab specimens from three patients at this school and carried out virus isolation with Vero/hSLAM cells and virus genome detection by reverse-transcription polymerase chain reaction. As a result, we isolated the virus from one patient and succeeded in amplifying the MV genome from the others. Further sequence analysis of the N gene revealed that these viruses were completely identical, and that their genotype could be characterized as type D9, which has not been reported in Japan previously. We also identified D9 viruses in two students at other junior high schools in Yamagata. These results suggested that D9 strains were imported from a region outside Japan. The genotypes of MVs found in Yamagata have changed in recent years, with D5 predominating in 2001 and H1 predominating in 2002 and 2003 as reported as national surveillance data. Therefore, we should monitor carefully to be sure that D9 strains do not become the next predominant virus. The more the number of measles cases decrease, the more important become the roles of public health laboratories, which genotype MVs and monitor their circulation and transmission pathways.

Re-emergence of echovirus type 13 infections in 2002 in Yamagata, Japan.

OBJECTIVES: To analyze the prevalence of echovirus type 13 (Echo13) in Yamagata, Japan. METHODS: Virus isolation was performed from 6514 clinical specimens using six cell lines between January 1999 and December 2002. We also carried out a seroepidemiological study against Echo13, using 234 serum samples collected in 2001. RESULTS: In 2002, we isolated a total of 50 Echo13 strains, which had not been detected from 1981 until 2001 in Japan. The antibody positive rate was higher (57.2-62.0%) in subjects 50 years or over than in those under 50 years (0-14.4%). CONCLUSIONS: Serological study suggested that Echo13 had been present in Yamagata until around 1960, at which time the antibody positive persons were exposed to Echo13 in their childhood. Furthermore, results of virus isolation demonstrated that Echo13 re-emerged in around 2002 after a hiatus of several decades.

Enterovirus isolation from children with acute respiratory infections and presumptive identification by a modified microplate method.

OBJECTIVE: To evaluate a modified microplate method, utilizing HEF, HEp-2, Vero, MDCK and newly introduced RD-18S and GMK cell lines, for virus isolation. METHODS: From June to October 2001, 723 throat swab specimens taken from children with acute respiratory infections (ARIs) were inoculated onto these cells. To analyze cell sensitivity, we also inoculated 20 serotypes of stocked enteroviruses. RESULTS: During the period, we isolated 40 Coxsackie A2 (CoxA2), 13 CoxA4, 16 CoxA16, 1 CoxB2, 11 CoxB3, 2 CoxB5, 54 echo16, 2 entero71 and 1 polio2. By observing a cell sensitivity pattern with HEF, HEp-2, Vero, RD-18S, and GMK, we could finally differentiate five enterovirus groups: CoxA except for CoxA16, CoxA16/entero71, CoxB, echovirus, and poliovirus. CONCLUSIONS: With this system, the RD-18S cell line enabled us to isolate CoxA virus, except for CoxA16, for the first time. Differentiation of five enterovirus groups by cell sensitivity simplified the specific identification by neutralization test as a presumptive identification. A modified microplate method may be an appropriate cell combination for virus isolation, especially for enteroviruses, and is expected to be used routinely for virologic diagnosis and to clarify the epidemiology of ARI in children.

A mutation on influenza C virus M1 protein affects virion morphology by altering the membrane affinity of the protein.

Reverse genetics has been documented for influenza A, B, and Thogoto viruses belonging to the family Orthomyxoviridae. We report here the reverse genetics of influenza C virus, another member of this family. The seven viral RNA (vRNA) segments of C/Ann Arbor/1/50 were expressed in 293T cells from cloned cDNAs, together with nine influenza C virus proteins. At 48 h posttransfection, the infectious titer of the culture supernatant was determined to be 2.51 x 10(3) 50% egg infectious doses/ml, which is lower than the number of influenza C virus-like particles (VLPs) (10(6)/ml) generated using the same system. By generating influenza C VLPs containing a given vRNA segment, we showed that each of the vRNA segments was similarly synthesized in the plasmid-transfected cells but that some segments were less efficiently incorporated into the VLPs. This finding leads us to speculate that the differences in incorporation efficiency into VLPs between segments might be a reason for the inefficient production of infectious viruses. Second, we generated a mutant recombinant virus, rMG96A, which possesses an Ala-->Thr mutation at residue 24 of the M1 protein, a substitution demonstrated to be involved in the morphology (filamentous or spherical) of the influenza C VLPs. As expected, rMG96A exhibited a spherical morphology, whereas recombinant wild-type of C/Ann Arbor/1/50, rWT, exhibited a mainly filamentous morphology. Membrane flotation analysis of the cells infected with rWT or rMG96A revealed a difference in the ratio of membrane-associated M1 proteins, suggesting that the affinity of M1 protein to the cell membrane is a determinant for virion morphology.

A slow spread of adenovirus type 7 infection after its re-emergence in Yamagata, Japan, in 1995.

We have continued the epidemiological study on adenovirus type 7 (Ad7), which re-emerged in 1995 in Yamagata, Japan. Between 1999 and 2004, we isolated only four strains from 10,778 throat swab specimens among children with acute respiratory infections. A serological survey of 303 specimens revealed the antibody-positive rate against Ad7 to be 0-7.4% in children under 10 years of age in 2005, although it was 3.3-16.7% in 1997 and 0% in 1993. Our results suggest that a re-emergence does not always provoke a sudden major outbreak, even if the antibody-positive rate against Ad7 is low in the local community.

A rare appearance of influenza A(H1N2) as a reassortant in a community such as Yamagata where A(H1N1) and A(H3N2) co-circulate.

To find a new influenza subtype A(H1N2), 383 isolates identified as H1 by hemagglutination inhibition test between the 1998-1999 and 2001-2002 seasons in Yamagata, Japan, were screened by reverse transcription polymerase chain reaction. As a result, 3 strains from the 1999-2000 season were identified as possibly being A(H1N2). Although several of their clones were found to be A(H1N2), A(H1N1) and A(H3N2), we could not confirm the origin of the A(H1N2) clones without the original specimens. These results suggest that a reassortment to produce A(H1N2) does not readily occur even when A(H1N1) and A(H3N2) co-circulate in a community such as Yamagata.