Capillaria hepatica

This name might look similar, as it is also a Capillaria type nematode. However, it presents very differently than Capillaria philippenensis! Instead of living inside fish eating birds, the adults of Capillaria hepatica lives in rat livers. Humans are the accidental (incidental) hosts.

This problem is found worldwide, but it is not very common. The adult worms get up to about 1 cm. The adults lay the eggs in the liver, where they stay in stasis until the rat is eaten by another animal. The purpose of this host is just to digest the liver - after this, the eggs pass out with the feces into the soil. The eggs hatch and then mature outside in the soil, where they are eaten again (hopefully by a rat), where they then migrate to the liver to complete their life cycle.

Humans typically get this infection by accidentally touching an area where the eggs have passed out. Most often this happens when a pet has eaten an infected rat. In humans, severe infections may result in fever, hepatomegaly, and hyper eosiniphilia, similar to a VLM infection. The eggs are then trapped in the liver, where they may cause an allergic reaction. This is a dead end stage for this parasite, unless the human's liver gets eaten and digested. (Hannibal situation?)

Diagnosis is made though liver biopsies, which will typically present adult worms and eggs. Usually humans will not pass any eggs in the feces. If they are, you know they got the infection in a different way- possibly if they ate an infected rat!

Photo Credit: cdc.gov

This is a liver section with eggs!

Eggs are similar to Capillaria philippenensis, in that they have bipolar prominences and a thick pitted shell.