Deer Liver Fluke

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Deer Liver Fluke

• By Kara

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Basic Information

• Scientific name Facioloides magna from Latin
  fasciolaband, magnalarge
• Class Trematode (Flukes)
• Phylum Platyhelminthes (Flatworms)

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Description

• Flat, enlongated, oval, look like blood
  suckers/ leaches
• Purple-gray color
• looks like a blood clot (in liver)
• Surrounded by fibrous capsule, bathed in a dark,
  muddy-appearing fluid.
• 15-30mm wide by 30-100mm long by 2-5mm thick

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Where it likes to live

• The natural host is the deer, which is also a
  reservoir host
• found in captive elk, but has not been observed
  in free elk.
• The fluke can also infect cattle, sheep, and
  llama.

• Some other states and Canadian report the fluke
  in moose, elk, white-tailed deer, mule deer,
  bison, and yak.
• It has also been reported in red deer, fallow
  deer, and sambar deer in Europe.

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Steps to infection

• Adult flukes deposit eggs in the ducts and
  cavities of the liver of the host.
• the eggs pass to the intestinal tract and are
  eliminated in the feces.
• The eggs need moisture for development, and will
  hatch in moist feces or shallow water

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Steps continued

• It takes about 25 days for eggs to hatch into the
  next stage, miracidia.
• Miracidia enter the snail as its next host
• In the snail, development proceeds to a
  sporoscyst form which can produce redia and
  daughter redia

• these redia produce cercaria, the final
  intramolluscan form
• Cercaria leave the redia while immature, and
  leave the snail after about four days

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Once outside the snail.

• cercaria encyst on vegetation
• these encysted forms are called metacercaria.
  They represent infective larvae, or young flukes,
  that are very resistant to the elements

• These are ingested by deer (or other host)
• the larvae penetrate the wall of the intestine,
  and migrate to the liver.
• The flukes develop in about three months.
• If all conditions are right, the cycle can be
  completed in five months.

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Damage to sheep

• In sheep these parasites do great damage to the
  liver
• uninterrupted migration throughout the liver
  causes massive hemorrhage and a peritonitis may
  develop
• sheep are the only host where the fluke causes
  such damage two or three of these parasites can
  cause death in a sheep.

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No damage here

• Cattle, bison, yak, and deer will encapsulate
  mature flukes in the liver, restricting their
  migration, and damage
• under experimental conditions, mule deer fawns
  and elk calves have died from fluke infection.

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Finding a Fluke

• examining visually for the parasites by making
  slices at 0.5 inch intervals through the entire
  liver
• Fibrous capsules may be visible on the lung
  surface

• It is also possible to diagnose flukes by
  microscopic examination of the feces for eggs of
  the parasite.

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Treatment

• fasciolicide drugs have been developed which are
  effective against mature Flukes.
• Triclabendazole in a medicated corn bait was
  given to white-tailed deer in a wildlife refuge
  in Texas

• resulting in the population of liver flukes being
  significantly lower

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Summary

• Deer liver flukes are not harmful to deer. The
  life cycle takes about 5 months for the Fluke and
  it spends 4 days living in a snail before it
  makes its way into the deer.
• (all information from http//www.michigan.gov/dnr/
  Pictures from google and that website)