Saturday, January 9, 2010

Information about Blastocystis

Above is a link to more information about Blastocystis from Wikipedia.


Anonymous said...

Contact the Blastocystis Research Foundation.


Mary Jo said...

Thanks Anonymous for these sites. I've read a lot about the Blastocystis Research Foundation and the incidences that were found in Oregon. It's odd to me that the Western United States seems to have more cases. I'm not sure if it's because we have the ocean, because more people travel to and from here, because we tend to diagnose things more, we swim more due to the nice weather, or what? I'd be curious to hear what everyone else thinks is the reason that more cases are being found here.

Anonymous said...

I definitely think it is the traveling aspect.

Mary Jo said...

This is interesting. We haven't really traveled. The school my daughter attends has many families that do travel over the summer to all different countries. Her school has an outdoor, swimming pool which all the children are required to swim in during PE classes every fall and spring. Do you think she could be getting it from the pool at the school? She seems to be symptomatic every fall and spring. I wasn't sure if this was the life cycle of the organism or she's getting reinfected each time since we still haven't conclusively identified the source of the infection.

Anonymous said...

I think the traveling aspect increases the risk of transmission in areas where the population tends to travel. You don't necessarily have to travel yourself to get Bh.

Mary Jo said...

Here's what the EPA sent from the CDC about Blastocystis:

Dear Ms Townzen,

This is an additional response from the EPA library, which had received your email regarding your daughter's situation.We were able to obtain a response from the Centers for Disease Control (CDC) in Atlanta, Georgia. I have pasted the response below. I hope that your daughter's situation will be resolved.


Rosemary Hardy, Reference Librarian/ ASRC Management Services
U.S. EPA Region 9 Library / 75 Hawthorne St. / San Francisco, CA 94105
415-972-3657 phone
415-947-3553 fax


Very little is known about Blastocystis and its status as a cause of disease is also unclear. In the absence of reliable data generated by appropriate clinical studies, there are no clear conclusions regarding the pathogenicity of this organism in the human host. Similarly, there is no agreement on what treatments are appropriate to eradicate Blastocystis carriage.

The classification of Blastocystis is still somewhat controversial. It is not a protozoan parasite as was previously suggested; Blastocystis is now known as a stramenopile, based on recently completed genomic sequencing. This places it among other unicellular and multicellular protists such as brown algae, diatoms, and water molds. There are 10 recognized subtypes of Blastocystis, which can only be differentiated by genetic sequencing and not by morphological criteria using microscopy or staining methods. The lifecyle and transmission routes of Blastocystis are undefined but it is presumed to spread by fecal-oral route of the cyst stage. In experimental studies, laboratory animals started shedding Blastocystis in their stool 1 to 2 days after infection by introduction of cysts directly into the stomach.

Blastocystis is commonly found in the stool of both symptomatic and asymptomatic or healthy people. Several possible ways for Blastocystis to cause disease have been proposed based on laboratory studies but none have been proven in epidemiological studies. Researchers in the academic arena are exploring whether or not some subtypes are associated with disease. When Blastocystis has been suspected to cause disease in individual patients, various treatments have been employed but no conclusive data on effective treatment has been generated, partly because of difficulties in assessing response to therapy, since reinfection may explain apparent treatment failure, and lack of knowledge about the natural history of Blastocystis carriage in the host. Currently, there is little known about how long Blastocystis will persist or if the organism will clear on its own at some point, i.e. that carriage of this organism is self-limiting.

With regard to the public health system, there are no requirements for reporting of Blastocystis when the organism is identified in stool samples at either the state or national level. The drug emetine is a very toxic drug and is not FDA-approved. This drug is stocked by the CDC Drug Service; physicians seeking to treat patients with emetine must first contact the FDA to obtain an individual IND (investigational new drug) protocol approval before this drug can be released. With regard to the question about research studies, physicians seeking to enroll their patients in clinical trials can consult the NIH website at for information on current and planned treatment trials.

I hope you find this information useful.


Susan P. Montgomery, DVM, MPH
Team Lead, Diagnostics and Epidemiology
Parasitic Diseases Branch
4770 Buford Highway, MS F-22
Atlanta, GA 30341-3724
Phone: 770.488.4520
Fax: 770.488.7761