Euryhelmis squamula (Rudolphi, 1819) Poche, 1926
(Figure 2-18)
ETYMOLOGY:Eury = wide and helmis = worm; squamula refers to the scale-like shape of the body.
SYNONYMS:Eurysoma of Dujardin, 1845; the name was already occupied for other organisms.
HISTORY: This fluke is known from mustelids and foxes in Europe and from mustelids and raccoons in North America. The metacercariae were first found encysted under the skin of a frog (Zeller, 1867)/
GEOGRAPHIC DISTRIBUTION: This trematode appears to have a holarctic distribution having been found in Europe and North America.
LOCATION IN HOST: Small intestine.
PARASITE IDENTIFICATION: The genus Euryhelmis is characterized by being a very wide trematode. This trematode differs from Euryhelmis monorchis in that it possesses two testes. The trematodes are about 1 mm long by 1 mm in width.
LIFE CYCLE: The life cycle has elucidated by Anderson and Pratt (1965). The snail used by the parasite in Oregon, US, was Bythinella hemphilli. The cercariae produced were found to have a tail that was one-third longer than the body with a dorsal fin fold. The cercaria penetrated and encysted under the skin of frogs (Ascaphus truei and Rana aurora). Metacercariae have also been recovered from the newt (Triturus cristatus) and toads. Cats have been experimentally infected by being fed metacercariae (McIntosh, 1936).
CLINICAL PRESENTATION AND PATHOGENESIS: Thought to be asymptomatic.
TREATMENT: Probably praziquantel, but not reported.
EPIZOOTIOLOGY: Cats would become infected by eating raw frogs, toads, or newts.
HAZARD TO OTHER ANIMALS: None known; however, due to the requirements for two intermediate hosts, it is unlikely that an infected cat would pose a direct threat to other animals.
HAZARD TO HUMANS: Humans might be infected if they were to eat uncooked or improperly cooked frog legs.
CONTROL/PREVENTION: The prevention of the ingestion of amphibia.
REFERENCES:
Anderson GA, Pratt I. 1965. Cercaria and first intermediate host of Euryhelmissquamula. J Parasitol 51:13-15.
McIntosh A. 1936. The occurrence of Euryhelmissquamula (Rud., 1819) in the United States> J Parasitol 22:536.
Zeller E. 1867. Ueber das enkystierte Vorkommen von Distomumsquamula Rud. in braunen Grasfrosh. Z Wissensch Zool 17:215-220.
Figure 2-18. Euryhelmissquamula from a raccoon in Georgia, US. Note the wide body of this genus of organisms.