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DPDx is an education resource designed for health professionals and laboratory scientists. For an overview including prevention and control visit www.cdc.gov/parasites/capillaria/.

Hepatic Capillariasis

[Capillaria hepatica]

Eggs of C. hepatica in liver stained with hematoxylin and eosin (H&E). The egg in this figure (1000x magnification) shows the typically striated shell and shallow polar prominences.

Eggs of C. hepatica in liver stained with hematoxylin and eosin (H&E). The egg in this figure (1000x magnification) shows the typically striated shell and shallow polar prominences.


Causal Agent

The nematode (roundworm) Capillaria hepatica causes hepatic capillariasis in humans.


Life Cycle

Life cycle of Capillaria hepatica.

Capillaria hepatica has a direct life cycle that requires only one host.  Adult worms invade the liver of the host (usually rodents, but may also be pigs, carnivores and primates, including humans), and lay hundreds of eggs in the surrounding parenchyma The number 1.  The eggs are not passed in the feces of the host, and remain in the liver until the animal dies and decomposes The number 2, or is eaten by a predator or scavenger The number 3.  Eggs ingested by such an animal are unembryonated, are not infectious, and are passed in the feces, providing an efficient mechanism to release eggs into the environment The number 4.  Cannibalism has been reported as an important role in transmission among rodent populations.  Eggs embryonate in the environment The number 5, where they require air and damp soil to become infective.  Under optimal conditions, this takes about 30 days.  The cycle continues when embryonated eggs are eaten by a suitable mammalian host The number 6.  Infective eggs hatch in the intestine, releasing larvae.  The larvae migrate via the portal vein to the liver.  Larvae take about four weeks to mature into adults and mate.  Humans are usually infected after ingesting embryonated eggs in fecal-contaminated food, water, or soil The number 7.  Occasionally in humans, larvae will migrate to the lungs, kidneys, or other organs.  The presence of C. hepatica eggs in human stool during routine ova-and-parasite (O&P) examinations indicates spurious passage of ingested eggs, and not a true infection.  Diagnosis in humans is usually achieved by finding adults and eggs in biopsy or autopsy specimens.

Geographic Distribution

Rare cases of human infections with C. hepatica have been reported worldwide.

Clinical Presentation

Hepatic capillariasis (C. hepatica) manifests as an acute or subacute hepatitis with eosinophilia, with possible dissemination to other organs. It may be fatal.

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  • Page last reviewed November 29, 2013
  • Page last updated November 29, 2013
  • Content source: Global Health - Division of Parasitic Diseases and Malaria
  • Notice: Linking to a non-federal site does not constitute an endorsement by HHS, CDC or any of its employees of the sponsors or the information and products presented on the site.
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