The Guinea worm, Dracunculus insignis, has been reported principally in southern Ontario from raccoon, mink and fisher.  In one study more than 50% of 287 raccoon and 194 mink from southern Ontario were infected with D. insignia (Crichton and Beverley-Burton, 1974).  The Guinea worm commonly found in otter is a different species known as Dracunculus lutrae (Crichton and Beverley-Burton, 1973).  D. lutrae has been found in 88% of a sample of 203 otter collected from throughout Ontario.  Specimens of Dracunculus have also been recovered from muskrat, short-tailed weasel and opossum of Ontario and from fox, dog, skunk, Bonaparte weasel and badger in other parts of North America.

Female D. insignia and D. lutrae are slender, whitish roundworms which are up to 28 centimetres long.  Males of both species appear dark, extremely slender and usually one-and-a-half to four centimetres in length.  Female worms are located subcutaneously between the skin and muscle on the thorax, abdomen, groin and legs of hosts.  Mature or gravid females which contain larvae or immature worms are usually located in the legs.  Male worms are rarely found elsewhere than in the subcutaneous tissues of the thorax, abdomen and groin.

The gravid female worm, in its position just under the skin in the legs, causes the development of a blister in the skin of the host which in time ruptures and is followed by the formation of an ulcer.  When this affected area comes in contact with water the worm discharges larvae through the ulcer into the surrounding water.  The larvae are then ingested by Cyclops sp., a small freshwater crustacean within which they develop until they are infective to the final host.  Some fish or frogs may ingest infected Cyclops and serve as reservoir hosts for the parasite.  The final host drinks water containing parasitized Cyclops or ingests infected reservoir hosts and the Dracunculus larvae are released into the intestinal tract.  The larvae then penetrate the wall of the host's intestine and migrate through the body cavity to connective tissues of abdomen, thorax and groin.  After mating male worms remain in this location and fertilized females migrate towards the legs.

The presence of either D. insignis or D. lutrae in an animal does not usually impair the quality of the pelt as in most instances the ulceration is confined to the legs.

D. insignis and D. lutrae are not mortality factors in the wild species they affect, nor are they known to be transmissible to man.

Selected References:

Crichton, V.F.J. and M. Beverley-Burton. 1973. Dracunculus lutrae n.sp. (Nematoda:Dracunculoidea) from the otter, Lutra canadensis, in Ontario, Canada.  Can.  J. Zool. 51:521-529.

Crichton, V.F.J. and M. Beverley-Burton. 1974.  Distribution and prevalence of Dracunculus spp. (Nematoda:Dracunculoidea) in mammals in Ontario.  Can.  J. Zool. 52:163-167.

Crichton, V.F.J. and M. Beverley-Burton. 1975.  Migration, growth, and morphogenesis of Dracunculus insignia (Nematoda:Dracunculoidea).  Can.  J. Zool. 53:105-113.