Incidence trend and risk factors for campylobacter infections in humans in Norway.
BACKGROUND
The objectives of the study were to evaluate whether the increase in incidence of campylobacteriosis observed in humans in Norway from 1995 to 2001 was statistically significant and whether different biologically plausible risk factors were associated with the incidence of campylobacteriosis in the different counties in Norway.


METHODS
To model the incidence of domestically acquired campylobacteriosis from 1995 to 2001, a population average random effect poisson model was applied (the trend model). To case data and assumed risk-factor/protective data such as sale of chicken, receiving treated drinking water, density of dogs and grazing animals, occupation of people in the municipalities and climatic factors from 2000 and 2001, an equivalent model accounting for geographical clustering was applied (the ecological model).


RESULTS
The increase in incidence of campylobacteriosis in humans in Norway from 1995 to 2001 was statistically significant from 1998. Treated water was a protective factor against Campylobacter infections in humans with an IRR of 0.78 per percentage increase in people supplied. The two-level modelling technique showed no evidence of clustering of campylobacteriosis in any particular county. Aggregation of data on municipality level makes interpretation of the results at the individual level difficult.


CONCLUSIONS
The increase in incidence of Campylobacter infections in humans from 1995 to 2001 was statistically significant from 1998. Treated water was a protective factor against Campylobacter infections in humans with an IRR of 0.78 per percentage increase in people supplied. Campylobacter infections did not appear to be clustered in any particular county in Norway.
Sandberg
Marianne
M
The Norwegian School of Veterinary Science, Oslo, Norway. marianne.sandberg@veths.no
Nygård
Karin
K
Meldal
Hege
H
Valle
Paul Steinar
PS
Kruse
Hilde
H
Skjerve
Eystein
E
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000818:Animals; D002167:Campylobacter / Q000302:isolation & purification; D002169:Campylobacter Infections / Q000453:epidemiology* / Q000209:etiology / Q000517:prevention & control; D002648:Child; D002675:Child, Preschool; D016000:Cluster Analysis; D004784:Environmental Monitoring; D062665:Epidemiological Monitoring; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D009111:Local Government; D008297:Male; D008875:Middle Aged; D009664:Norway / Q000453:epidemiology; D016012:Poisson Distribution; D011159:Population Surveillance; D011200:Poultry / Q000382:microbiology; D018570:Risk Assessment; D012307:Risk Factors; D014871:Water Microbiology; D018508:Water Purification