title: Investigation of Swedish cases reveals an outbreak of cryptosporidiosis at a Norwegian hotel with possible links to in-house water systems.
abstract: BACKGROUND
  In March 2007, the Norwegian Institute of Public Health was notified of Swedish individuals diagnosed with cryptosporidiosis after staying at a Norwegian hotel. In Norway, cryptosporidiosis is not reportable, and human infections are rarely diagnosed.
  
  
  METHODS
  A questionnaire on illness and exposure history was e-mailed to seven organised groups who had visited the hotel in March. Cases were defined as persons with diarrhoea for more than two days or laboratory-confirmed cryptosporidiosis during or within two weeks of the hotel visit. The risk factor analysis was restricted to two groups with the highest attack rates (AR) and same hotel stay period. Local food safety authorities conducted environmental investigations.
  
  
  RESULTS
  In total, 25 diarrhoeal cases (10 laboratory-confirmed) were identified among 89 respondents. Although environmental samples were negative, epidemiological data suggest an association with in-house water consumption. In one group, the AR was higher amongst consumers of water from hotel dispenser (relative risk [RR] = 3.0; 95% confidence interval [CI]: 0.9-9.8), tap water (RR = 2.3; CI: 0.9-5.8), and lower amongst commercial bottled water drinkers (RR = 0.6; CI: 0.4-1.0). Consumption of ice cubes was a risk-factor (RR = 7.1; CI: 1.1-45.7) in the two groups combined.
  
  
  CONCLUSIONS
  This outbreak would probably have remained undetected without the alert from Swedish health authorities, illustrating the difficulties in outbreak detection due to low health care seeking behaviour for diarrhoea and limited parasite diagnostics in Norway. Awareness of cryptosporidiosis should be raised amongst Norwegian medical personnel to improve case and outbreak detection, and possible risks related to in-house water systems should be assessed.
authors.affiliation: Department of Infectious Disease Epidemiology, Norwegian Institute of Public Health, Oslo, Norway. agneshajdu@yahoo.com
authors.forename: Agnes
authors.initials: A
authors.lastname: Hajdu
authors.forename: Line
authors.initials: L
authors.lastname: Vold
authors.forename: Torild A
authors.initials: TA
authors.lastname: Østmo
authors.forename: Anna
authors.initials: A
authors.lastname: Helleve
authors.forename: Sigrid R
authors.initials: SR
authors.lastname: Helgebostad
authors.forename: Truls
authors.initials: T
authors.lastname: Krogh
authors.forename: Lucy
authors.initials: L
authors.lastname: Robertson
authors.forename: Birgitta
authors.initials: B
authors.lastname: de Jong
authors.forename: Karin
authors.initials: K
authors.lastname: Nygård
mesh_terms: D000818:Animals; D003457:Cryptosporidiosis / Q000453:epidemiology / Q000469:parasitology*; D003458:Cryptosporidium / Q000235:genetics / Q000302:isolation & purification*; D003967:Diarrhea / Q000453:epidemiology / Q000469:parasitology; D004196:Disease Outbreaks; D005260:Female; D005618:Fresh Water / Q000469:parasitology*; D006801:Humans; D008297:Male; D009664:Norway / Q000453:epidemiology; D012150:Polymorphism, Restriction Fragment Length; D011795:Surveys and Questionnaires; D014881:Water Supply / Q000032:analysis*; D044465:White People