The incidence of norovirus-associated gastroenteritis and the molecular epidemiology of norovirus strains were studied during three seasons (2000-2001, 2001-2002, and 2002-2003) among patients of all ages, mainly from the Stockholm region in Sweden. A total of 3,252 fecal samples were analyzed by reverse transcription-PCR. The incidences of norovirus infection among adults were 23, 26, and 30% during the three seasons studied and 18, 11, and 15% among children 0 to 15 years of age. During the first season, all norovirus strains detected by PCR were typed either by reverse line blot hybridization or nucleotide sequence analysis. During the two successive seasons, a total of 60 norovirus-positive strains from the beginning, peak, and end of the seasons were selected for nucleotide sequence analysis. We identified two dominant norovirus variants over the seasons: a new norovirus variant, recently described as the GGIIb genetic cluster, dominated among children during the first season, and during the following two seasons, a GGII-4 variant dominated. Our data suggest that norovirus infections are common, not only among adults, but also among children, and that some strains may predominantly affect children.

Enteric viruses play an important role in pediatric diarrhea during the winter season in China. A combination of microscopic examination of stool samples with specific EIA assays to detect virus antigen in stool specimens may be suitable for routine diagnostics.

Children with multiple viral findings in their respiratory secretions were older than those with a single detected virus. Otherwise, no major differences in comorbidity, presentation or clinical outcome were observed between the two groups.

The epidemiology and genetic variability of circulating respiratory syncytial virus (RSV) strains in Stockholm during the season 2002-2003 were studied in consecutive RSV isolates derived from respiratory samples and diagnosed in the laboratory. Two hundred thirty-four viruses were sequenced. The samples were mainly from children under 1 year old (79%). The phylogeny of the N-terminal part of the G gene was studied after amplification and sequencing. One hundred fifty-two viruses belonged to subgroup B and 82 to subgroup A. The subgroup A viruses could be further divided into genotypes GA2 (25) and GA5 (57) and the subgroup B viruses into GB3 (137) and SAB1 (15) strains. These strains clustered with subgroup A and subgroup B strains from Kenya from the same period, as well as with strains from Great Britain from 1995 to 1998. The dominance of subgroup B strains in Stockholm during 2002-2003 is in agreement with findings from other parts of the world during the same years. Only two genotypes of subgroup A, GA2 and GA5, were circulating during this time, and GA2 has been circulating in Sweden for more than 20 years. Consecutive strains from the same individual displayed no variability in the sequenced region, which was also true of strains that had been passaged in cell cultures.

No abstract