Capillaria hepatica is a parasitic nematode which causes hepatic capillariasis in rodents and numerous other mammal species, including humans.

[citation needed] Adults are often found in dozens of rodent species, but also occur in a wide variety of other wild and domestic mammals, and occasionally humans.

[5][6] C. hepatica has been found in temperate and tropical zones on every continent and infestation rates of wild-caught rats of up to 100% have been reported.

[13] Once these "environmentally-conditioned" eggs are eaten by a suitable host, the first stage larvae (L1) hatch in the intestine and continue the life cycle.

[8] However, as the adult C. hepatica begin to die in the liver tissue, their decomposition accelerates the immune response of the host.

[15] This response leads to chronic inflammation and encapsulation of the dead worms in collagen fibers, and eventually to septal fibrosis (abnormal connective tissue growth) and cirrhosis of the liver.

Infections of C. hepatica can present with several clinical symptoms, including abdominal pain in the liver area, weight loss, decreased appetite, fever and chills, hepatitis (liver inflammation), ascites (excess fluid in the peritoneal cavity) and hepatolithiasis (gallstones in the bile ducts).

[8] Diagnosis is made by finding eggs or adults of C. hepatica in liver tissue from biopsy or necropsy samples.

[1] The encapsulated eggs and adults may appear as white nodules which measure 2–3mm in diameter on the surface and interior of the liver at autopsy.

[20] Two calcified objects recovered from a 3rd to 4th-century grave of an adolescent in Amiens (Northern France) were identified as probable hydatid cysts.

The authors claimed that hepatic capillariasis could be expected given the poor level of environmental hygiene prevalent in this period.

Identification of tissue-dwelling parasites such as C. hepatica in archaeological remains is particularly dependent on preservation conditions and taphonomic changes and should be interpreted with caution due to morphological similarities with Trichuris sp.