The many faces of Crohn’s Disease: Latest concepts in etiology

The notion that Crohn’s Disease (CD) occurs as a result of an aberrant reaction to the commensal microbiota in genetically susceptible hosts is widely regarded by physicians and scientists as fact. Yet although it is undisputed that Crohn’s Disease is immune-mediated, an aberrant reaction to one’s own native flora is far from proven. The aim of the current review is to present a summary of the known infectious causes of Crohn’s Disease, whilst highlighting the limitations of using outdated methods to attempt to classify the disease as a single entity. We propose a re-classification of Crohn’s Disease, and suggest that the disease is best conceptualized as a syndrome, an “umbrella-like” term comprising a group of diseases with varying infective etiologies, which clinically, endoscopically and histologically are indistinguishable from CD.