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Med Hypotheses. 2007;69(3):652-9. Epub 2007 Mar 26.

Is this recently characterized gastrointestinal pathogen responsible for rising rates of inflammatory bowel disease (IBD) and IBD associated autism in Europe and the United States in the 1990s?

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  • 1Blastocystis Research Foundation, 5060 SW Philomath Blvd, #202 Corvallis, OR 97333-1044, USA.


In 2006, a pathogenic variant of the common intestinal organism Blastocystis was discovered in patients who were experiencing chronic gastrointestinal symptoms. Most species of Blastocystis inhabit humans with no symptoms. The discovery of a pathogenic variant of Blastocystis is significant, because Blastocystis is related to Entamoeba, a similar organism with pathogenic variants that kill over 100,000 people each year. Recent research has shown that Blastocystis infections may be undetectable using existing clinical methods. Medical case reports from the Middle East, Europe, and United States suggest that infection with this variant may already be widespread and misdiagnosed as one of several functional disorders.


A more virulent or transmissible type of Blastocystis emerged in the Middle East in the 1980's, and was transmitted to Europe and the United States by military and more significantly vacation and business travel. The lack of adequate tests made it impossible to detect the infection. Transmission to the larger population resulted in rising inflammatory bowel disease (IBD) rates in Europe in the 1990's. The relationship between IBD and autism is explored, along with the possibility that the same pathogen causes both conditions.


Serological and epidemiological findings are presented supporting the hypothesis. Blastocystis survives sewage treatment, shows low host specificity, and can be spread by many animals. Several communities which have been studied due to high autism rates are located close to rivers which receive large quantities of sewage effluent, such as South Thames (England), Olmsted County (Minnesota, USA) and many communities in Oregon (USA).


Scientists from other countries represent the first line of defense against emerging infectious diseases, but their publications on Blastocystis are not well known in the United States and Europe. With the publication of corroborating research by Western scientists in core scientific journals, it is hoped that an appropriate response from the public health system will be forthcoming. Investigation into the existence of infection in the groups mentioned with sensitive and specific tests should be performed. Such tests could include a serum antibody test and a Polymerase Chain Reaction test specific to the pathogenic variant.

[PubMed - indexed for MEDLINE]
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