Trematodes in Crayfish


Category 4 (Negligible Regulatory Significance in Canada)

Common, generally accepted names of the organism or disease agent

Metacercarial infection of crayfish, Trematode infections.

Scientific name or taxonomic affiliation

  1. Various species of Digenea including metacercariae of Paragonimus spp., Crepidostomum cornutum, Orchipedium (=Distoma) sp., Mariteminoides medium, Macroorchis spinulosus.
  2. Adults of Allocorrigia filiformis in the trematode family Dicrocoeliidae (Turner and Corkum 1977).

Geographic distribution

  1. Global, although each species probably has a confined distribution.
  2. Swamps in the vicinity of Baton Rouge, Louisiana.

Host species

  1. Many species of crayfish including Procambarus sp., Orconectes sp., Cambarus sp., and Cambaroides sp. Metacercariae have also been reported from marine crustaceans including lobsters and crabs.
  2. Procambarus clarkii.

Impact on the host

Majority of the species are innocuous. However, the wound produced by the invading cercaria may provide an entry for secondary infection. Also heavy infections may have a seriously debilitating, perhaps lethal, effect. Some species of the genus Macroorhic are infectious to mammals and species of Paragonimus can cause serious problems for humans if crayfish from infected areas in Asia are eaten raw.

Unlike most other trematode infections in crustaceans, Allocorrigia filiformis, in the antennal glands of a high percentage of P. clarkii in Louisiana, attains sexual maturity in its invertebrate host. Eggs of A. filiformis containing active miracidia occur in the excretory tubules of the crayfish antennal gland and probably exit the crayfish via the excretory pore of the antennal gland. Although up to three A. filiformis were observed threaded through the interstices of the antennal gland and in some crayfish both antennal glands were infected, no evidence of pathology was described (Turner and Corkum 1977).

Diagnostic techniques

Squash Preparations: Trematodes (including metacercariae) can be observed in thin slices (about 3 mm thick) of tissue pressed between two glass plates and examined under a dissecting microscope (50 × magnification). Many species encyst in specific organs of the crayfish

Histology: Cross sections of trematodes can be observed in stained tissue sections.

Methods of control

Prevention and control impractical in the field. In intensive culture contact with molluscan first intermediate hosts should be avoided.


Alderman, D.J. and J.L. Polglase. 1988. Pathogens, parasites and commensals. In: D.M. Holdich and R.S. Lowery (eds.). Freshwater Crayfish ­ Biology, Management and Exploitation. Timber Press, OR., p. 195-197.

Chai, J.-Y., W.-M. Sohn, S. Huh, M.-H. Choi and S.-H. Lee. 1996. Redescription of Macroorchis spinulosus Ando, 1918 (Digenea: Nanophyetidae) encysted in the fresh water crayfish, Cambaroides similis. The Korean Journal of Parasitology 34: 1-6.

Sogandares-bernal, F. and J.R. Seed. 1973. American Paragonimiasis. Current Topics in Comparative Pathobiology 2: 1-56.

Turner, H.M. and K.C. Corkum. 1977. Allocorrigia filiformis gen. et sp. n. (Trematoda: Dicrocoeliidae) from the crayfish, Procambarus clarkii (Girard, 1852). Proceedings of the Helminthological Society of Washington 44: 65-67.

Citation Information

Bower, S.M., McGladdery (2003): Synopsis of Infectious Diseases and Parasites of Commercially Exploited Shellfish: Trematodes in Crayfish.

Date last revised: April 2003
Comments to Susan Bower

Date modified: