High incidence of Campylobacter concisus in gastroenteritis in North Jutland, Denmark: a population-based study.

The incidence of non-thermophilic Campylobacter species was assessed in an unselected population-based study in a mixed urban and rural community in North Jutland, Denmark. In a 2-year study period, 11,314 faecal samples from 8302 patients with gastroenteritis were cultured with supplement of the filter method. We recovered a high incidence of Campylobacter concisus (annual incidence 35/100,000 inhabitants), almost as high as the common Campylobacter jejuni/coli. In contrast, there was a very low incidence of other non-thermophilic Campylobacter species, such as Campylobacter upsaliensis. Campylobacter concisus was, unlike C. jejuni/coli, found more frequently among small children (<1 year) and the elderly (≥ 65 years). Around 10% of the patients with C. consisus had co-infections dominated by Clostridium difficile and Salmonella enterica, whereas co-infections occurred in about 5% of C. jejuni/coli patients. We observed a seasonal variation in C. jejuni/coli with a peak incidence in late summer months and autumn, whereas there was an almost constant monthly prevalence of C. concisus. Among patients participating in a questionnaire sub-study, there was a higher degree of close contacts with animals, especially dogs, as well as a higher travel exposure among C. jejuni/coli patients compared with C. concisus patients. We did not culture any C. concisus in stool samples from a small cohort of healthy individuals. Future studies have to focus on the clinical follow-up and the long-term risk of inflammatory bowel diseases in C. concisus-positive patients. We conclude that there is a high incidence of C. concisus in Denmark.