human calicivirus outbreak of acute gastroenteritis in an aged-care facility

Abstract

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.