SUMMARY:
The author discusses possible aethiological causes of Crohn´s disease taking into consideration the undoubtedly significant impact of the constitution of the intestinal microbial flora. The author pays special attention to Yersinia; their presence in the intestine is believed to be the chief mechanism of subsequent immunity events resulting in the development of the disease. The author briefly discusses the possibilities of differential diagnosis and of treatment. He mentions the profitable cooperation of an infectious disease specialist and a gastroenterologist in the diagnosis of diarrhoeal disorders.