In Oshima, the southern part of Hokkaido, a tick-borne encephalitis (TBE) patient was found in 1993; in addition TBE virus was isolated from the blood samples of sentinel dogs, ticks pools, and rodents spleens in 1995 and 1996 by suckling mice. To identify when these TBE viruses emerged in Hokkaido, the times of divergence of TBE virus strains isolated in Oshima and Far Eastern Russia were estimated. TBE virus was isolated in Khabarovsk in 1998, and the nucleotide sequences of viral envelope protein genes of isolates from Oshima and Khabarovsk were compared. Based on the synonymous substitution rates of these virus E-protein genes, the lineage-divergence times of these TBE virus strains were predicted phylogenetically to be approximately 260-430 years ago. Furthermore, the virulence of TBE virus isolates from Oshima and Khabarovsk were compared in a mouse model. The results showed that the isolates possessed very similar virulence in mice. European TBE vaccine was found to be effective in TBE virus, Hokkaido strain. This review provides evidence that the Oshima strains of TBE virus in Hokkaido emerged from the Far Eastern Russia a few hundred years ago, which explains why the virulence of these strains is similar to that of TBE viruses isolated in Russia. Practical application of the vaccine should be considered in Japan.

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The AMPLICOR CMV (qualitative DNA assay by PCR), COBAS AMPLICOR CMV Monitor (quantitative DNA assay by PCR), and antigenemia assay were tested for their ability to diagnose cytomegalovirus (CMV) infection in 115 immunocompromised patients. The AMPLICOR qualitative assay and the antigenemia assay were positive for all nine patients with a clinical diagnosis of CMV disease. The AMPLICOR quantitative assay was negative for one of the nine patients. In 106 patients without CMV disease, the AMPLICOR qualitative test was positive in 22, the quantitative test was positive in 23, and the antigenemia test was positive in 55 patients. The AMPLICOR qualitative and quantitative assays had specificities of 79% and 78% in patients without CMV disease, while that of the antigenemia assay was 48%. Diagnostic efficiencies were 79% for the AMPLICOR qualitative assay, 69% for the AMPLICOR quantitative assay, and 48% for the antigenemia assay. All three tests yielded positive results before, or at the same time as, the onset of CMV disease in most cases, which suggests they can be used to predict disease before the onset of symptoms. During antiviral treatment, test results tended to decrease quantitatively and finally became negative; negative results were followed by remission of symptoms. This suggests that the AMPLICOR quantitative assay and the antigenemia assay could be useful for monitoring therapeutic efficacy. The AMPLICOR qualitative and quantitative assays, as well as the antigenemia assay were considered effective for all of the following: diagnosing CMV disease, predicting the onset of disease, and evaluating the effectiveness of antiviral chemotherapy. The antigenemia assay was at times difficult to perform in the case of severely neutropenic patients, whereas the AMPLICOR assays could be used in such cases.

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In July, 1999, an outbreak of vancomycin-resistant Enterococcus faecalis (VREF) with the vanB genotype occurred for the first time in Japan at Hokushin General Hospital, Nakano City, Nagano Prefecture. Four VREF strains were isolated from the clinical specimens of four inpatients, and 16 VREF strains were isolated by the screening of asymptomatic carriers and by surveillance of the hospital environment. All of the isolates possessed vanB genes. In a pulsed-field gel electrophoresis analysis, 19 out of 20 VREF isolates exhibited the indistinguishable restriction endonuclease digestion patterns of the chromosomal DNA. Additional investigation by Southern hybridization using the vanB probe implied that the vanB gene of these 19 isolates was encoded on a 110-kb plasmid. These findings indicate that the outbreak was principally caused by a single clone. The restriction endonuclease digestion patterns of the remaining single isolate was different from those of the other isolates. The vanB gene was encoded on the chromosome.

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Fecal samples from 232 weaned piglets (1 and 3 months old) and 252 fattening porkers (6 months old) in 8 stock-raising farms located in Kanagawa Prefecture, Japan, from June 1998 to June 2000 were examined to determine the prevalence of Cryptosporidium infection. Detection of oocysts was performed using the ethyl acetate fecal concentration method and immunofluorescent staining. C. parvum oocysts were identified in 77 (33.2%) 1-3 months old weaned piglets from four farms. The odds of excreting among 1-3 months old piglets were more than 100 times greater than among 6 months old porkers (95% confidence interval: 17-902). This strongly suggests that weaned piglets are important reservoirs of pathogenic microbes whose potential contamination of drinking water has epidemiological implications for human health.

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In order to evaluate the Japanese nationwide school absenteeism surveillance system for pediatric influenza in comparison with the national sentinel surveillance for influenza, we used surveillance guidelines (Centers for Disease Control and Prevention, 1998) to determine the efficacy of the school health surveillance system (SHSS). Data regarding school absenteeism (age 4-15 years old) was compared with data regarding influenza-like illness (ILI) per sentinel sites during the second to the 11th weeks of 1998 and 1999. Despite the system's high simplicity and acceptability, telecommunication costs were estimated at US$ 490,000 (1998). Representativeness of schoolchildren was very accurate, but ILI for pre-school children (4-6 years) remained uncountable. Sensitivity, specificity, and positive predictive value of the SHSS compared to sentinel surveillance were calculated as 80%, 100%, and 100%, respectively (P = 0.004). Although the SHSS was found to provide accurate surveillance data during periods of high influenza activity, non-influenza virus infections (e.g., adenovirus, rotavirus, and Norwalk virus, etc.) may become mixed in the SHSS data. Evaluation using this system should be continued employing a new case definition excluding gastrointestinal symptoms.

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