Dicrocoelium spp

From Cow
Dicrocoelium adult under light microscopy

Dicrocoelium spp (Lancet liver fluke) is a zoonotic[1] parasitic trematode (fluke) of cattle worldwide.

Species which are pathogenic in cattle include:

  • Dicrocoelium dendriticum[2]

The life cycle involves intermediate snail hosts (Lymnaea spp) with infective metacercariae that are eaten by cattle during grazing. The adult fluke usually resides in the bile duct of cattle and cause extensive liver disease during their migration. Once mature, the flukes pass eggs into the bile, which are passed out in the feces and contaminate pasture. Other animals, as well as humans become infected by eating uncooked beef.

Clinical signs are often vague in cattle and laboratory testing for Dicrocoelium eggs and elevated bilirubin and liver enzyme on blood tests may help determine a diagnosis[3]. In acute infections, acute hepatitis is a common sequelae, which usually leads to cirrhosis in more chronic cases. Bile duct walls may become greatly thickened and calcified and adult flukes may also be found in aberrant sites such as the lungs.

Diagnosis is based on presenting clinical signs, isolation of the parasite eggs in feces, identification of adult flukes in the liver and laboratory analysis of parasite for identification. Commercially available ELISA are also available in some countries.

Control of this parasite is through use of molluscicides to control the snail (intermediate host) as well as flukicidal drugs such as triclabendazole, closantel, moxidectin plus triclabendazole and oxyclozanide[4].

References

  1. El-Shafie AM et al (2011) Zoonotic Dicrocoeliasis dendriticum in a farmer's family at Giza Governorate, Egypt. J Egypt Soc Parasitol 41(2):327-336
  2. Ekstam B et al (2011) Predicting risk habitats for the transmission of the small liver fluke, Dicrocoelium dendriticum to grazing ruminants. Geospat Health' 6(1):125-131
  3. Arias M et al (2011) Prevalence of mixed trematode infections in an abattoir receiving cattle from northern Portugal and north-west Spain. Vet Rec 168(15):408
  4. Merck Vet Manual