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Background. Human caliciviruses represent a genetically and antigenetically diverse group of single-stranded RNA viruses associated with acute gastroenteritis in humans. In last two years the number of notified gastroenteric cases in Slovenia is increasing. From January till November 2002 already 574 calicivirus cases have been confirmed. Majority of cases were observed in preschool and school children but no cases were described in the aged-care facility.Methods. An outbreak of gastroenteritis in an aged-care facility occured. After onset of the outbreak an epidemiological questionnaire and inspection of local conditions were realized. Stool samples from home residents were analysed to find out bacteriological and/or viral aetiology. Direct electron microscopy and RT-PCR assay was performed to detect caliciviruses. Viral RNA was amplified using specific primers and PCR products were identified in hybridisation test.Results. The outbreak started suddenly on the second floor, where the attack rate was the highest. On the other floors the illness started later and the attack rate was lower. Sixty-one (40,1%) residents from 152 became ill and additionally 15 (22,4%) employees from 67. The outbreak ended after ten days. Electron microscopy or/and RT-PCR revealed Norovirus members of family Caliciviridae in 9 of 10 stool specimens. As determined by RT-PCR and hybridisation assay viruses corresponded to genogroup II, genetic cluster 1 (closely related to the Hawaii virus) and genetic cluster 4 (closely related to the Lordsdale virus).Conclusions. Presented data support a significant role for caliciviruses as causative agents of gastroenteritis in elderly persons in Slovenia.

Background. Human caliciviruses represent a genetically and antigenically diverse group of single-stranded RNA viruses associated with acute gastroenteritis in humans. In last two years the number of notified gastroenteric cases in Slovenia is increasing. Samples were analysed by direct electron microscopy (EM). For increased sensitivity RT-PCR assay was performed. Using molecular methods for the detection of caliciviruses we tried to detect causative agent in outbreaks where no viruses were found by direct EM.Methods. After onset of outbreak an epidemiologic questionnaire was performed, hygienic testing, and determination of pathogenic bacteria. Latex agglutination for determination of rota- and adenoviruses 40/41 were performed. Additionally ELISA test for determination of astroviruses was used. Stool samples were examined by direct electron microscopy. RNA was isolated from 15 positive samples in which small roundstructured viruses (SRSVs) were observed. RNA was amplified by RT-PCR using specific primers and the obtained products were confirmed in hybridisation test.Results. 20 children from 97 and 2 adults form 20 became ill. Symptoms included diarrhoea, vomiting and fever lasting for 1 to 3 days. None of patients sought medical help neither were hospitalized. Obtained food samples were not contaminated. From five hygienic smears coagulase positive staphylococci were isolated. All stool samples tested for pathogenic bacteria were negative, as well as for rota- and adenoviruses. Electron microscopy revealed 15 stool samples containing SRSVs. 11 of them were positive for caliciviruses, corresponding to genogroup II (GG II), as determined by RT-PCR and hybridisation assay.Conclusions. If an outbreak in the community is reported early or at least soon enough caliciviruses can be identified by RTPCR and hybridisation assay and the outbreak could be restricted to limited area.