Outbreak of norovirus in Västra Götaland associated with recreational activities at two lakes during August 2004.
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.
Sartorius
Benn
B
European Programme for Intervention Epidemiology Training (EPIET), Solna, Sweden. Benns@nicd.ac.za
Andersson
Yvonne
Y
Velicko
Inga
I
De Jong
Birgitta
B
Löfdahl
Margareta
M
Hedlund
Kjell-Olof
KO
Allestam
Gorel
G
Wångsell
Claes
C
Bergstedt
Olof
O
Horal
Peter
P
Ulleryd
Peter
P
Soderstrom
Ann
A
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