CXCL8 and infection: In human infection studies, stools become C. jejuni culture-positive 48 hours after bacterial ingestion, and there is, on average, 88.5 hours between ingestion and the onset of diarrhea.12 A study that followed a single patient before and after C. jejuni infection found that there was a strong induction of IL-1β, IL-8, IL-6, IFN-γ, and C-reactive protein in the serum at 3 to 10 days after onset of symptoms.13C.