Increased Incidence of Inflammatory Bowel Disease: The Price of the Decline of Infectious Burden?

Hélène Feillet; Jean-François Bach


Curr Opin Gastroenterol. 2004;20(6) 

In This Article

Lessons From Other Immune Disorders

The data presented above are suggestive of a protective role of infections for IBD. Their significance should be interpreted in the context of similar and better-documented data obtained in allergic and autoimmune diseases.[3] The increased incidence in developed countries and uneven geographical distribution are fully substantiated with a North-South incidence gradient. The role of socioeconomic levels and sanitary conditions is well documented in the case of allergic diseases, where direct evidence was obtained of a negative correlation between environmental endotoxin levels (used as a surrogate marker of bacterial infections) and incidence of atopic diseases.[29] It was also noted in the case of atopy and insulin-dependent diabetes mellitus (IDDM) that in families with several children, the firstborn child, who is less exposed to siblings' infections shows higher disease incidence than siblings of higher birth rank. The causal relation between decline of infections and increased disease incidence is indicated by the study of a wide spectrum of spontaneous or experimentally induced animal models of autoimmune or allergic diseases where disease prevention is obtained by deliberate infection by a number of pathogens (bacteria, viruses, or parasites) and by the demonstration (in the case of human atopic dermatitis), that the disease is prevented or improved by oral intake of nonpathogenic lactobacilli.[30,31] Collectively, these data bring strong evidence that the decline of infections observed in developed countries is at the origin of the increased incidence of allergic and autoimmune diseases. There is still much uncertainty, however, about the identity of the pathogens that are involved in this protection.


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