Dicrocoelium dendriticum: Lancet fluke

General Description: Lancet-shaped fluke, 6 to 10 mm long and 1.5 to 2.5 mm wide.

Life Cycle: Two intermediate hosts are necessary: a snail and an ant. The miracidium hatches after the egg has been swallowed by the snail. Cercariae are produced in about 3 months and are eliminated from the snail by way of slime balls. When the slime balls are ingested by ants the metacercariae develop in the ant´s abdominal cavity. Cattle are infected by eating infected ants on pasture. The cattle´s digestive process releases metacercariae, which are immature flukes. These enter the liver through the common bile duct of the intestine. After approximately 11 to 12 weeks, adults are capable of producing eggs.

Location: Bile ducts and gallbladder of liver.

Geographical Distribution: Lancet flukes are reported in Europe, Asia, North America, and North Africa.

Significance: Lancet flukes may cause extensive liver damage, causing the host to "do poorly". Condemnation of infected livers at slaughter is a serious economic loss when many cattle in a herd are infected. A distinguishing factor is that the lancet fluke enters the liver from the intestine via the bile duct.

Effect on Host: The fluke damages the liver and, in heavy infections, may cause cirrhosis of the liver and enlargement of bile ducts. Blood loss results in anaemia and oedema. Infected animals lose weight.

Diagnostic Information: Eggs, each containing a miracidium, may be found in faeces.

Control: Elimination of land snails is difficult. Deworming of cattle that have flukes is the most effective means of reducing parasite loads.

Dicrocoelium - adult