Campylobacter species in broiler chickens.

The incidence of Campylobacter spp. in broiler chickens in Northern Ireland was determined by examining three groups of birds. These included: (1)12 flocks of broilers monitored at regular intervals from their introduction into commercial units until the time of slaughter; (2) 21 batches of unsolicited birds submitted to the laboratory for postmortem examination; and (3) 13 batches of chicks under 36 hours old. Most birds became infected but Campylobacter spp. were not usually isolated during the first 2 weeks of life. C. jejuni biotype 1 was the predominant species isolated although C. coli and an atypical strain were also isolated. At least five distinct serotypes were present (Penner sero-types 1,3,5,9 and 11) of which serotypes 1 and 9 were most common. In birds older than 2 weeks of age, an association was sometimes observed between the sudden occurrence of wet litter and the presence of C. jejuni in all or the majority of the birds sampled. Infection of broilers under 2 weeks of age was accompanied by mortality.