The following have been implicated in outbreaks: Contact with infected animals (eg, puppies) Contact with contaminated food or water (eg, handling contaminated food) Ingestion of contaminated food (especially undercooked poultry), water, or unpasteurized raw milk Person-to-person transmission through fecal-oral and sexual contact may also occur but is uncommon because a large number of Campylobacter organisms are required to cause infection.