Population dynamic and within-host adaptation of Campylobacter jejuni in pre-weaned healthy dairy calves

Understanding the emergence, persistence and transmission Campylobacter jejuni within livestock herds is a prerequisite to identify on-farm management practices that control the human infections sourced from bovine animals. Our objective was to characterise C. jejuni population in dairy calves during the pre-weaning period and to explore the impact of exposure to wild birds on C. jejuni diversity and population changes in calves. Forty-eight dairy calves were reared in three indoor pens till weaning. Two pens were covered with orchard bird netting to prevent bird access, while one pen had unrestricted access to birds. A total of 8 faecal samples were collected from each calf from birth till weaning at approx. 10 weeks old, and the genetic relatedness of C. jejuni isolates was evaluated by MLST and cgMLST. The study demonstrated the importance of time in influencing C. jejuni population in the gut of healthy pre-weaned dairy calves; it also suggested potential news avenues for farm-specific C. jejuni mitigation strategies.