Infectious Disease and Microbiology – Dicrocoelium dendriticum

Overview

Dicrocoelium dendriticum is a trematode helminth, commonly referred to as the lancet liver fluke. Human infection is rare and is usually asymptomatic, although the parasite may occasionally involve the biliary tract and cause symptoms such as biliary colic.

Microbiologic Characteristics

D. dendriticum is a trematode (fluke) that primarily inhabits the biliary system of its usual mammalian hosts.

Human infection is unusual and generally occurs accidentally.

Epidemiology

Dicrocoelium dendriticum has a worldwide distribution, but true human infection is rare.

Its eggs may sometimes be identified in human stool specimens without indicating genuine infection.

Spurious Passage of Eggs

A particularly important point is that eggs of D. dendriticum may appear in stool after a person eats infected animal liver.

In this situation, the parasite has not established infection in the patient. The eggs are simply passing through the gastrointestinal tract.

Therefore, detection of D. dendriticum ova in stool does not always prove true human parasitism.

Clinical Infection

Most true infections are asymptomatic.

When symptoms occur, they are usually related to the biliary tract and may include:

• Right upper quadrant discomfort

• Intermittent biliary pain

• Biliary colic

Symptomatic disease is exceptional.

Diagnosis

Diagnosis is based on parasitologic examination of stool specimens for characteristic eggs.

Because false-positive or spurious egg passage can occur, stool findings should be interpreted together with the clinical picture and dietary history.

Repeated stool examinations may help distinguish true infection from transient passage after ingestion of infected animal liver.

Treatment

Treatment is generally unnecessary in asymptomatic patients.

For the rare patient with symptomatic infection in whom other causes of biliary symptoms have been excluded, the source recommends:

Praziquantel 25 mg/kg orally every 8 hours for 3 doses

High-Yield Clinical Pattern

Dicrocoelium eggs found in stool

• ●

No compatible symptoms

• ●

Recent ingestion of animal liver

→ Consider spurious passage rather than true infection

Exam Essentials

Organism: Dicrocoelium dendriticum

Type: Trematode helminth

Common name: Lancet liver fluke

Distribution: Worldwide

Human infection: Rare

Typical course: Usually asymptomatic

Possible manifestation: Biliary colic

Diagnosis: Stool parasitologic examination

Important pitfall: Eggs in stool may represent spurious passage after eating infected animal liver

Treatment for symptomatic true infection: Praziquantel

Key clinical pearl: Finding Dicrocoelium dendriticum eggs in stool does not automatically mean true infection; first consider spurious passage from recently consumed infected liver.