Intestinal Protozoan Parasites

Author: Margaret Reinhart, MS, MLS(ASCP)
Reviewers: Diane M. Valentin, MS, MLS(ASCP)MB and Laurie Bjerklie, MA, MLS(ASCP)CM
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Continuing Education Credits

P.A.C.E.® Contact Hours: 2 hour(s)

Florida Board of Clinical Laboratory Science CE Credit Hours

Florida Board of Clinical Laboratory Science CE - General (Microbiology/Mycology/Parasitology): 1.5 hour(s)

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This course is intended as a survey or overview of the protozoa (protista) that can be found in the human intestinal tract, and how to diagnose them. A brief introduction of each parasite, including its epidemiology and life cycle will be given. The emphasis will then be on key diagnostic features.

Objectives

  • Describe each of the commonly found protozoan parasites found in human feces.
  • Describe how a patient gets infected by each parasite.
  • Identify microscopic images of each parasite based on key diagnostic criteria.
  • Differentiate those protozoa that are capable of causing disease from those which are commensal.
  • Describe other (besides microscopy) diagnostic tests which can be used for the detection and identification of some of the commonly found parasites.

Course Outline

  • Introduction to the Intestinal Parasitic Protozoa
    • The World of Parasites
    • Introduction to Protozoa
    • Classification of the Protozoa
    • Classification of Intestinal Protozoa by Locomotion
    • Match the parasite group with their type of locomotion.
  • Overview of Diagnostic Techniques
    • Types of Diagnostic Techniques
    • Collection and Processing for Performing the Microscopic Exam
    • Collection and Processing for Performing the Microscopic Exam: Fixatives
    • Concentration Techniques
    • How to Perform the Microscopic Exam
    • Entero-Test (Duodenal Capsule)
    • Molecular Methods
    • Antigen and Antibody Detection
    • Suggested Protocols for Parasite Recovery
    • True or False: A direct wet prep for examining stool specimens for ova and parasites is a preferred method for parasite detection and identification.
    • All of the following are stains that can be used on permanent smears for protozoa except:
  • Life Cycles, Epidemiology, Diseases, and Diagnosis of the Amoebae
    • Pathogenic versus Commensal Amoebae
    • Entamoeba histolytica Life Cycle
    • Entamoeba histolytica Epidemiology and Disease
    • Differentiating E. histolytica Trophozoites from the Commensal Amoeba Trophs
    • Differentiating E. histolytica Cysts from the Commensal Amoeba Cysts
    • Other Diagnostic Techniques for Entamoeba histolytica
    • Match the amoeba species with whether it is pathogenic or commensal.
    • True or False: People become infected with Entamoeba histolytica by consuming food contaminated (usually of human fecal origin) with trophozoites of the organism.
    • An MLS is puzzled when she finds cysts resembling E. histolytica or E. hartmanni. A way of distinguishing Entamoeba histolytica cysts from cysts of Entamoeba hartmanni is:
    • Common methods of detecting pathogenic gastrointestinal infection with Entamoeba histolytica include all of the following except:
  • Life Cycles, Epidemiology, Diseases, and Diagnosis of the Flagellates
    • Pathogenic versus Commensal Flagellates
    • Giardia and Dientamoeba Life Cycles
    • Giardia and Dientamoeba Epidemiology and Disease
    • Differentiating Giardia and Dientamoeba Trophozoites from the Commensal Flagellated Trophozoites
    • Differentiating Giardia and Dientamoeba Cysts from those of the Commensal Flagellates
    • Other Diagnostic Techniques for Giardia and Dientamoeba
    • A physician suspects that a patient may be infected with Giardia and orders an O&P exam. Examination of a trichrome-stained smear on the loose stool is negative for ova and parasites. Why does this not definitively rule out the presence of Giardia?
    • Match the trophozoite to the image from a trichrome-stained smear.
    • The best methods for diagnosing G. duodenalis trophozoites include all of the following except:
  • Life Cycle, Epidemiology, Disease, and Diagnosis of the Ciliate Balantidium coli
    • Life Cycle, Epidemiology, and Disease Caused by Balantidium coli
    • Diagnosis of Balantidium coli
    • An O&P exam is ordered. It is noted that Blantidium coli infection is suspected. The best method for diagnosis is:
  • Other Intestinal Protists
    • Blastocystis spp: Epidemiology, Disease, and Life Cycle
    • Blastocystis Diagnosis
    • Intestinal Sporozoa: Cryptosporidium spp., Cyclospora cayetanensis, Cystoisospora belli, and Sarcocystis spp.
    • Cryptosporidium spp.
    • Cyclospora cayetanensis
    • Cystoisospora belli (formerly Isospora belli)
    • Sarcocystis spp.
    • Microsporidia
    • Summary of the Morphologic Features of Blastocystis, Sporozoa, and Microsporidia
    • The sporozoa are characterized by all of the following except:
    • A laboratorian performs an acid-fast stain on a fecal smear and finds several round, acid-fast structures measuring 8–10 μm. The most likely diagnosis is:
    • True or False: The organisms belonging to the Microsporidia group have an obligate extracellular phase of development.
  • References
    • References

Additional Information

Level of Instruction:  Intermediate to Advanced
Intended Audience: Medical laboratory scientists, medical laboratory technicians, laboratory supervisors, and laboratory managers. This course is also appropriate for MLS and MLT students and pathology residents.
Author Information: Margaret Reinhart, MS, MLS(ASCP), is a Senior Lecturer emerita in Biological Sciences at the University of the Sciences in Philadelphia, PA, where she taught hematology, clinical immunology, parasitology, and other related courses, as well as directed the MLS program for over 30 years. She is currently an adjunct instructor in Hematology at Pennsylvania Hospital, Philadelphia, PA.  She holds a Master's Degree in Biology and Health Care Administration.
The author has no conflict of interest to disclose.
Reviewer Information: 
Diane M. Valentin, MS, MLS(ASCP)MB, is a graduate of the University of the Sciences in Philadelphia who has worked as a medical laboratory professional since graduation. She also earned a Master of Science degree in biomedical informatics, focusing on bioinformatics, from Rutgers University and a certificate in molecular laboratory diagnostics from Michigan State University. She holds two certifications from the American Society of Clinical Pathology as a Medical Technologist and Technologist in Molecular Biology.
Laurie Bjerklie, MA, MLS(ASCP)CM, is a Lead Education Developer. She earned a B.S. in Medical Laboratory Science from the University of North Dakota and an M.A. in Curriculum and Instruction from Saint Xavier University. She has over 15 years of experience in higher education and has held program director and faculty positions in both MLT and MLS programs.