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User:Gastro guy/blc

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History

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The Blastocystis controversy refers to a disagreement between physicians and researchers concerning whether infection with the protozoan Blastocystis causes symptoms in humans. Blastocystis is a genus of gastrointestinal parasites which infect a wide variety of mammals, birds, amphibians, reptiles and fish.

During the first 8 decades of the 20th century, sporadic medical reports from physicians appeared in the literature describing patients who has symptoms of diarrhea and abdominal pain, and who were found to be infected only with Blastocystis:

In 1984, one researcher noted that Blastocystis case reports "began to increase" [ZIERDT_1991]. During the period 1900-1970, nn reports of Blastocystis infection appeared the the literature. During the period 1985-1990, nn reports were submitted:

Two physicians began responding to the reports - EK Markell, MP Edkow, and Additionally, one microbiological study indicated lack of serum immune response on patients infected. A counter-report (lack of serum immune resonse) 2889924

Markell and Udkow wrote an additional article in JCM in 1988:

An additional one reporting no association: 3055191 - other explanations

Highlights: Invasiveness2322029 2333700 One of the largest reports from Saudi Arabia: 2808664 Prompted reply from Department of Laboratories, North Shore University Hospital, Manhasset, New York., indicaitng they had seen it in many patients without symptoms

Main points of controversy (1990)

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Blastocystis is harmless

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The points made here were that:

  1. Koch's postulates had never been proven
  2. Never has been an epidemic or point
  3. No immune response
  4. In my clinical experience, the people who have this do not have symptoms. The ones who have symptoms can be explained by other causes.
  5. Wide range of symptoms (Variable Pathogenicity)
  6. There is no drug that consistently cures the infection
  7. In some patients, treatment


Blastocysti causes disease

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  1. Koch's postulates not proven with many diseases
  2. There may be more than one species


Publications Since 1990

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Supporting Non-Pathogenicity:

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Supporting Pathogenicity:

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  1. Koch's postulates were proven in studies by three different research groups
  2. Epidemics were reported several times
  3. Earlier Chen study only looked for Igg1 response - Igg2 response shown in two studies to be present only in symptomatic infection
  4. Suggestion that may be two species confirmed - nine separate species groups (see phylogentics and pathogenicity below)
  5. New protozoa found that are not responsive to drugs
  6. Testing found to be msising most infections

Supporting Both: The finding regarding phylogentics has been proposed to provide an explanation for why researchers in different areas of the world were reporting different results.


Professional Opinions: Similar long-standing disagreements have existed for other gastorintestinal pathogens, such as Giardia, H Pylori, Cholera. Medicine lacks a central governing body. Scientists are free to express opinions. Even in cases like AIDS, some physicians still dissent as to whether HIV is the cause, and there opinion, although considered fringe, has guided the policy of South Africa.


Recent Development

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Asia:

  • Experimental Blastocystis infection in mice was reported to produce intestinal lesions and invasive infection (College of Public Health, Zhengzhou University) pmid 17094618
  • Experimental infection in mice was reported to produce severe intestinal damage, infection through entire gastrointestinal tract, weight loss, lethatrgy, and and death in mice (16566218
  • Researchers at University of Malaysia reported that the type of Blastocystis which causes disease is genetically distinct from a similar looking harmless type, and that it behaves differently in culture.


North America:

  • A study reported that patients infected with Blastocystis exhibited extra-intestinal symptoms of skin rash, fatigue, and headaches.
  • An article published in Medical Hypotheses noted that symptoms reported in Blastocystis infection are similar to those of Persian Gulf veterans, and suggested that Gulf War Syndrome may be the result of Western physicians failing to recognize the significance of the infectinon.
  • An article published in Oregon's Gazette Times newspaper identified patients chronically infected with Blastocystis, experiencing medical disability and severe intestinal symptoms. The article noted 50% of returning veterans were found to carry Blastocystis infection.
  • The Oregon State Legislature considered a bill requiring the health department to track Blastocystis infection. THe Oregon Department of Human Services opposed the bill and indicated more research was needed on Blastocystis infection.
  • A search of the National Institutes of Health CRISP Grant Funding Databse shows that no NIH grant has been awarded for funding Blastocystis research in United States in the last 10 years

Middle East:

  • Saudi officials identified Blastocystis as a foodborn infection, noting that leafy vegetables were widely contaminated with Blastocystis cysts. 16680247
  • 79% of patients in Turkey with Blastocystis were found to have gastrointestinal illness 17124674
  • Physicians noted patients presenting with abdominal pain, fever, appearing to require appendectomy, actually infected with Blastocystis, 16863863
  • A study from Turkey found an association between Blastocystis infection and stunting in children. 17179909

Europe:

  • A Denmark study reported that conventional diagnostic techniques fail to detect aubstantial number of infections even in patients with diarrhea, and that these can not be detected with culture methods. Study recommended use of special purpose diagnostics.

Australia:

  • A study performed in Melbourne, Australia reported a lack of association between Blastocystis infection and symptoms

Tables

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References

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