title: Outbreak of norovirus in Västra Götaland associated with recreational activities at two lakes during August 2004.
abstract: A large community outbreak of norovirus (NV) gastrointestinal infection occurred in Västra Götaland County, Sweden in August 2004, following attendance at recreational lakes. A frequency age-matched case control study was undertaken of persons who had attended these lakes to identify risk factors. 163 cases and 329 controls were included. Analysis indicates that having water in the mouth while swimming (OR=4.7; 95% CI 1.1-20.2), attendance at the main swimming area at Delsjön Lake (OR=25.5; 95% CI 2.5-263.8), taking water home from a fresh water spring near Delsjön lake (OR=17.3; 95% CI 2.7-110.7) and swimming less than 20 m from shore (OR=13.4; 95% CI 2.0-90.2) were significant risk factors. The probable vehicle was local contamination of the lake water (especially at the main swimming area). The source of contamination could not be determined.
authors: European Programme for Intervention Epidemiology Training (EPIET), Solna, Sweden. Benns@nicd.ac.za
authors: Benn
authors: B
authors: Sartorius
authors: Yvonne
authors: Y
authors: Andersson
authors: Inga
authors: I
authors: Velicko
authors: Birgitta
authors: B
authors: De Jong
authors: Margareta
authors: M
authors: Löfdahl
authors: Kjell-Olof
authors: KO
authors: Hedlund
authors: Gorel
authors: G
authors: Allestam
authors: Claes
authors: C
authors: Wångsell
authors: Olof
authors: O
authors: Bergstedt
authors: Peter
authors: P
authors: Horal
authors: Peter
authors: P
authors: Ulleryd
authors: Ann
authors: A
authors: Soderstrom
mesh_terms: D000293:Adolescent; D000328:Adult; D017250:Caliciviridae Infections / Q000453:epidemiology*; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks; D005260:Female; D005618:Fresh Water / Q000821:virology*; D005759:Gastroenteritis / Q000453:epidemiology* / Q000821:virology; D006306:Health Surveys; D006801:Humans; D007223:Infant; D008297:Male; D029322:Norovirus; D011998:Recreation; D012307:Risk Factors; D013548:Sweden / Q000453:epidemiology; D013550:Swimming