Case #526 – October, 2020
During a field study in Cambodia, stool ova and parasite (O&P) examinations were performed on participants in rural villages. Unusual eggs were found in the formalin-ethyl acetate concentrated stool specimen of one middle-aged woman. Shown in figures A – C are the eggs, which measured an average of 53 x 32 µm. What is your diagnosis? What does this indicate about the patient’s diet, and are any follow-up actions necessary?
These eggs belong to Capillaria hepatica (=Calodium hepaticum). However, when eggs of this species are found in human stool, this indicates spurious passage following ingestion of an infected animal liver. True hepatic capillariasis is rare and is diagnosed by detection of eggs or adult worms in liver biopsy/autopsy specimens. In areas where both C. hepatica and C. philippinensis occur, the larger size and thicker shells of C. hepatica are differentiating features.
Diagnostic features shown included:
- Barrel-shaped eggs measuring 50—70 µm x 30—35 µm, which are unembryonated. Capillaria philippinensis eggs are smaller, measuring only 35 to 45 µm by 20-25 µm and are passed in feces.
- Thick, striated shell.
- Non-protruding polar plugs.
More on: Capillaria hepatica
Images presented in the monthly case studies are from specimens submitted for diagnosis or archiving. On rare occasions, clinical histories given may be partly fictitious.
DPDx is an educational resource designed for health professionals and laboratory scientists. For an overview including prevention, control, and treatment visit www.cdc.gov/parasites/.