SMALL ROUND-STRUCTURED (NORWALK-LIKE) VIRUSES AND CLASSICAL HUMAN CALICIVIRUSES IN SOUTHEASTERN AUSTRALIA, 1980-1996

A total of 6,226 fecal samples collected from 1980 to 1996 in the Aust ralian states of Victoria, New South Wales, and Tasmania from individu als with gastroenteritis were tested for small round-structured viruse s (SRSVs) and classical human caliciviruses (ClHuCVs) by electron micr oscopy. There were 223 samples positive for SRSVs, and nine positive f or ClHuCVs. SRSVs were detected in individuals of all ages and were co mmonly associated with gastroenteritis outbreaks in nursing homes and hospitals. SRSVs were detected throughout the year, but were more comm on in the period from late winter to early summer in Australia (August to December). There were peaks of virus activity in the early 1980s a nd more recently in 1995 and 1996. Analyses by RT-PCR and sequencing o f a segment of ORF1 encoding the putative RNA polymerase for SRSVs and ClHuCVs showed the presence of viruses belonging to several genogroup s. Viruses of genogroup 1 (Norwalk/Southampton-like) and genogroup 3 ( ClHuCVs) were relatively rare. Viruses of genogroup 2 (Snow Mountain-l ike) were common, and could be divided into two subgroups,one containi ng Toronto/Mexico-like viruses, the other Lordsdale/Camberwell-like vi ruses. The majority of viruses detected belonged to this latter subgro up. (C) 1998 Wiley-Liss, Inc.