Enhanced surveillance of campylobacter infection in the North West of England 1997-1999.

OBJECTIVES: To identify sources and routes of infection for sporadic cases of campylobacter infection in the North West of England.
METHODS: Standard, structured questionnaires were used to gather epidemiological information from cases of campylobacter infection in the North West Region of England between 1997 and 1999. The strains of campylobacter isolated from these cases were identified and typed using serotyping and phage typing methods. Analysis of combined serotype and epidemiological data is presented. RESULTS AND
CONCLUSIONS: Human campylobacter infection in the North West is seasonal and a new observation was a peak in cases in March each year. Drinking bird-pecked milk was a highly seasonal exposure that might be an indicator of environmental contamination with campylobacter. A possible environmental basis for seasonality of infection is discussed. Frequencies of risk exposures related to serotypes of cases are described and a potential association was demonstrated between Campylobacter jejuni HS6 and consumption of bird-pecked milk. Also, Campylobacter coli infections were more commonly associated with travel abroad than C. jejuni and a decreased proportion of C. jejuni HS2 and C. jejuni HS11 reported consumption of meat and unpasteurised milk (respectively). Contact with a sick animal may be a significant risk exposure in younger age groups and in those who do not consume poultry or meat. It is clear from this and other studies that the sources and vehicles of human campylobacter infection are numerous and interventions that target a single risk factor are unlikely to impact significantly on the overall burden of disease.