Dicrocoeliasis (Lancet Liver Fluke Disease)
Parasite: Dicrocoelium dendriticum (Trematode)
Geographic Range: Europe, Asia, North America (introduced)
Hosts:
- Definitive Host: Grazing animals (sheep, cattle) (accidental: humans)
- Intermediate Hosts:
- First Intermediate Host: Land Snail
- Second Intermediate Host: Ant
Transmission: Humans accidentally ingest infected ants in water or food.
Symptoms: Abdominal pain, gallbladder inflammation (often asymptomatic)
Adult Worm:
- Size: 8-14mm long, 2mm wide
- Morphology:
- 2 suckers (oral and ventral)
- Irregular shaped testes and ovaries
- Nervous system of ganglion
- Excretory system of protonephridia type
Life Cycle:
- Eggs shed in feces of definitive host (sheep, cattle)
- Eggs ingested by snail
- Miracidia hatch in snail and migrate to tissues
- Miracidia develop into sporocysts
- Sporocysts produce daughter sporocysts
- Daughter sporocysts produce cercariae
- Cercariae leave snail in slime
- Ant ingests cercariae (cercariae become metacercariae)
- Definitive host ingests infected ant
Metacercariae excyst in small intestine and mature in liver
Notes:
- Dicrocoeliasis is a liver disease caused by the trematode Dicrocoelium dendriticum.
- Grazing animals are the main hosts, but humans can accidentally become infected.
- Infection is often asymptomatic.
- Treatment is available for human cases.