Intestinal Worms
Continuing Education Credits
This parasitology course covers the common helminth (worm) parasites found in human feces. Discussed in the course is 1) how a patient gets infected by each of the intestinal parasites based on the worm's life cycle, 2) microscopic images of each parasite based on diagnostic criteria, and 3) clinical signs and symptoms caused by each helminth parasite.
Appropriate specimens, as well as specimen collection, processing, and methods of microscopic examination are covered along with other diagnostic identification methods.
Objectives
- Recall and briefly describe each of the common helminth (worm) parasites found in human feces.
- Describe how a patient gets infected by each of the intestinal parasites based on the worm's life cycle.
- Identify microscopic images of each parasite based on diagnostic criteria.
- Describe clinical signs and symptoms caused by each helminth parasite.
- Describe appropriate specimens, as well as specimen collection, processing, and methods of microscopic examination.
- Describe other diagnostic methods besides microscopic examination.
- Recognize those helminth species in which the human can host the larval phase in their tissues.
Course Outline
- Introduction to the Helminth (Worm) Parasites found in Human Feces.
- The World of Parasites
- Classification of the Helminths Found in the Gastrointestinal Tract
- Classification of the Intestinal Helminths, continued
- Diagnostic Techniques: The O&P Exam
- Other Techniques for Diagnosing Intestinal Helminths
- Match the common name with the scientific name.
- You receive a stool specimen for O&P in 10% formalin. All of the following procedures can be performed from this specimen except:
- The Trematodes (Flukes)
- Classification of the Trematodes
- Morphology of the Flukes
- Life Cycles of the Flukes (Trematodes) Living in the Intestinal Tract
- Life Cycles of the Flukes Living in the Biliary System and Lungs
- Life Cycles of Schistosoma spp. Living in the Veins
- Diagnosing the Trematodes
- Diagnosing the Trematodes, continued
- Comparison of the Trematode Egg Sizes
- Clinical Symptoms and Treatments of the Flukes
- Match the identification with the image of the egg.
- The following are common among all flukes except:
- An O&P is ordered on a patient with abdominal discomfort and diarrhea, who had just returned from a trip to Asia. A microscopic exam is done on the sediment of a formalin/ethyl-acetate concentrate and the following structure is seen. The structure was approximately 142 x 72 µm. Which of the following best fit this scenario? (Check all that apply.)Figure 9.
- The Cestodes (Tapeworms)
- Classification of the Cestodes
- Morphology of the Tapeworms
- Life Cycles of the Tapeworms
- Life Cycles of the Tapeworms, continued
- Diagnosing the Tapeworms
- Clinical Symptoms and Treatment of Tapeworms
- Match the identification with the image of the egg.
- An O&P is performed on a child who complains of a "tummy ache." The child has not traveled outside of the area. Several of these structures are seen in the microscopic wet mount.
- Match the name of the tapeworm with the name of its larval form.
- The Nematodes (roundworms)
- Classification of the Nematodes
- Classification of the Nematodes, continued
- Life Cycles of Nematodes
- Life Cycles of Nematodes, continued
- Diagnosing the Intestinal Nematodes
- Clinical Symptoms and Treatment of Intestinal Nematodes
- True or False: Many of the nematodes' life cycles require water for the development of their eggs or larvae.
- A child is suspected of having a pinworm infection. What type of specimen should be ordered, and what would you look for?
- Several eggs similar to the one in the image were seen on a formalin-ethyl acetate concentrate done on a child with abdominal pain. The child lives in a rural area of the US and has never traveled outside the country. The eggs measured approximately 63 x 37 µm. What is your diagnosis?
- Summary and More Hints on Diagnosing Intestinal Worms
- Importance of Size
- Importance of Proper Specimen Collection
- Artifacts
- All of the following are recommended fixatives for performing concentration techniques on stool specimens except:
- This structure is seen when examining a direct wet prep. It measures approx. 98 x 60 µm. How would you identify it?
- References
- References
Additional Information
Level of Instruction: Intermediate
Intended Audience: Medical laboratory scientists, medical technologists, and technicians. This course is also appropriate for medical laboratory science students and pathology residents.
Author Information: Margaret Reinhart MS, MLS(ASCP), is a senior lecturer at the University of the Sciences where she has taught Human Parasitology since 1986. She was director of the Medical Laboratory Science Program from 1990-2020. She also did research on various aspects of Parasitology.
The author has no conflict of interest to disclose.
Reviewer Information: Judi Bennett, BSM, MLS(AMT), MLT(ASCP), is an Education Developer with MediaLab by Vastian, bringing over 30 years of experience as a medical laboratory scientist. Before joining MediaLab in 2010, she held key leadership roles, including Clinical Laboratory Manager, Microbiology Supervisor, and Senior Systems Analyst at Gwinnett Health System in Lawrenceville, Georgia. Her extensive knowledge of laboratory operations and a strong commitment to health care quality and education fuel her passion for developing engaging and effective learning tools for the next generation of laboratorians.
Course Description: This course is intended as an overview/review of the common helminth parasites that can typically be diagnosed from a stool specimen. The majority live in the intestines, although a few live in other organs, but their eggs can be found in the feces. The focus is on microscopic identification; some information on other diagnostic methods, life cycles, epidemiology, symptoms and treatment is also given.