title: Prevalence and molecular epidemiology of noroviruses detected in outbreak and sporadic cases of acute gastroenteritis in Bulgaria.
abstract: Noroviruses constitute a genetically diverse group of viruses in the Caliciviridae family, and are recognized as an important cause of acute non-bacterial gastroenteritis worldwide. To date there are no data on the incidence of noroviruses as a cause of gastroenteritis in Bulgaria. Fecal samples from an outbreak, and sporadic cases of diarrhea that occurred between December 2006 and April 2007 were tested for the presence of noroviruses. From a total of 474 stools (341 from sporadic cases and 133 cases from a single outbreak) examined, 72 samples (37 from sporadic cases and 35 from the outbreak) were positive using a norovirus-specific enzyme immunoassay. Fifty-nine specimens were confirmed and genotyped by RT-PCR and sequencing of regions of the RNA-dependent RNA polymerase and/or capsid. Sequence and phylogenetic analyses of 29 norovirus strains revealed a great diversity of norovirus genotypes among the sporadic cases including: GGII.3, GGII.4/2006a, GGII.4/2006b, GGII.20, and GGII.Karachi. A single norovirus genotype (GGII.4/2006b) was identified as the causative agent of the outbreak. This first investigation on the prevalence and molecular epidemiology of noroviruses demonstrates the significant role of these viruses as etiologic agents in acute gastroenteritis in Bulgaria.
authors.affiliation: National Reference Laboratory of Enteroviruses, National Center of Infectious and Parasitic Diseases, Sofia, Bulgaria. zornitsavmbg@yahoo.com
authors.forename: Zornitsa
authors.initials: Z
authors.lastname: Mladenova
authors.forename: Neli
authors.initials: N
authors.lastname: Korsun
authors.forename: Tsvetelina
authors.initials: T
authors.lastname: Geonova
authors.forename: Ilaria
authors.initials: I
authors.lastname: Di Bartolo
authors.forename: Lucia
authors.initials: L
authors.lastname: Fiore
authors.forename: Franco Maria
authors.initials: FM
authors.lastname: Ruggeri
mesh_terms: D002031:Bulgaria / Q000453:epidemiology; D017250:Caliciviridae Infections / Q000453:epidemiology* / Q000821:virology*; D016000:Cluster Analysis; D004196:Disease Outbreaks; D004797:Enzyme-Linked Immunosorbent Assay; D005243:Feces / Q000821:virology; D005759:Gastroenteritis / Q000453:epidemiology* / Q000821:virology*; D005838:Genotype; D017720:Molecular Epidemiology; D029322:Norovirus / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D010802:Phylogeny; D015995:Prevalence; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D017385:Sequence Homology