Laboratory Studies

Laboratory studies that may be used in the diagnosis of diphyllobothriasis include the following:

Microscopic stool examination for ova and parasites ^[33]: In Taenia species, stool examination has a poor sensitivity of 51.5 to 68%. For Diphyllobothrium infestation, more data is required to determine whether the sensitivity of microscopy for detection of ova and parasites is higher given that Diphyllobothrium adults produce > 1 million eggs per day compared to 300,000 eggs per day by Taenia species. ^{[34, 35, 36]}
Complete blood count (CBC) - Eosinophilia may be present
Hemoglobin level and hematocrit - These may be below or at the lower end of the reference range. The anemia produced by diphyllobothriasis is typically associated with increased free hydrochloric acid in gastric juice, in contrast to the relative achlorhydria invariably observed in true pernicious anemia.
Mean cell volume - This may be above or at the higher end of the reference range
Peripheral smear
Vitamin B-12 level
Folate level

Diagnosis of D latum infection is based on identification of the ovoid and operculated eggs in the stool with a typical knob on the end opposite the operculum. The stool sample does not require concentration for visualization of the eggs. Usually, this is not difficult, because of the large quantity of eggs (≥1 million) produced each day. Also frequently seen in stool are the trapezoid-shaped mature proglottids, which are wider than long and have a rosette-shaped gravid uterus with a central uterine pore. While species identification on gross morphologic appearance is difficult, it may not have much clinical relevance as treatment of Diphyllobothriasis is the same regardless of the species. Species identification through multiplex PCR studies sequencing the COX1 gene, subsequently helps clarify the intermediate hosts and is important for epidemiological purposes and disease prevention.^{[37, 38, 39, 40]}

Proglottids of Diphyllobothrium latum.

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Egg of Diphyllobothrium latum with arrow pointing to operculum.

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Other Studies

In general, no imaging studies are required to evaluate diphyllobothriasis, unless they are clinically indicated by other aspects of the patient’s presentation. For example, patients who present with obstruction require appropriate testing, starting with both flat and upright abdominal radiography. Abdominal ultrasonography, a real-time, non-invasive test might detect the hyperechoic, ribbon-like structure freely floating in the intestinal lumen.^[8]

On occasion, cases of diphyllobothriasis have been successfully identified by means of upper endoscopy or capsule endoscopy.^{[13, 41, 42]}

Treatment & Management

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Media Gallery

Life cycle of diphyllobothrium.
Egg of Diphyllobothrium latum with arrow pointing to operculum.
Proglottids of Diphyllobothrium latum.
Diphyllobothrium life cycle. This illustration depicts the life cycle of different species of Diphyllobothrium parasitic cestodes, the causal agents of the disease diphyllobothriasis. Courtesy of the Centers for Disease Control and Prevention (CDC) (https://www.cdc.gov/dpdx/diphyllobothriasis/).

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Author

Shireen R Chacko, MBBS Resident Physician, Department of Internal Medicine, Albert Einstein Medical Center

Disclosure: Nothing to disclose.

Coauthor(s)

Antonette B Climaco, MD Attending Physician, Division of Infectious Diseases, Department of Medicine, Einstein Healthcare Network

Antonette B Climaco, MD is a member of the following medical societies: American Academy of HIV Medicine, HIV Medicine Association, Infectious Diseases Society of America, Philippine Medical Association

Disclosure: Nothing to disclose.

Chief Editor

Pranatharthi Haran Chandrasekar, MBBS, MD Professor, Chief of Infectious Disease, Department of Internal Medicine, Wayne State University School of Medicine

Pranatharthi Haran Chandrasekar, MBBS, MD is a member of the following medical societies: American College of Physicians, American Society for Microbiology, International Immunocompromised Host Society, Infectious Diseases Society of America

Disclosure: Nothing to disclose.

Additional Contributors

David R Haburchak, MD, FACP Key Faculty, Wellstar Kennestone Internal Medicine Residency Program, Wellstar Health System

David R Haburchak, MD, FACP is a member of the following medical societies: American College of Physicians, American Osler Society, American Society for Microbiology, Christian Medical and Dental Associations, Infectious Diseases Society of America

Disclosure: Nothing to disclose.

Derek Ryan Linklater, MD Assistant Professor of Military and Emergency Medicine, F Edward Hebert School Of Medicine; Assistant Clinical Professor of Emergency Medicine, Texas A&M Health Science Center College of Medicine; Clinical Instructor of Pediatrics, Baylor College of Medicine

Derek Ryan Linklater, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Emergency Medicine, Society for Academic Emergency Medicine, American College of Emergency Physicians

Disclosure: Nothing to disclose.

Coburn H Allen, MD Assistant Professor of Pediatrics, Dell Children's Hospital

Coburn H Allen, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Pediatrics, Infectious Diseases Society of America, Pediatric Infectious Diseases Society

Disclosure: Nothing to disclose.

Acknowledgements

Thomas M Kerkering, MD Chief of Infectious Diseases, Virginia Tech Carilion School of Medicine

Thomas M Kerkering, MD is a member of the following medical societies: Alpha Omega Alpha, American College of Physicians, American Public Health Association, American Society for Microbiology, American Society of Tropical Medicine and Hygiene, Infectious Diseases Society of America, Medical Society of Virginia, and Wilderness Medical Society