Cercaria

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cercaria

[sər′kar·ē·ə]
(invertebrate zoology)
The larval generation which terminates development of a digenetic trematode in the intermediate host.

Cercaria

 

the larva of parasitic worms of the class Trematoda. The body, which measures 0.3–1 mm in length, has an oral and a ventral sucker. Cercariae have a furcately branched intestine, a nervous system, sometimes ocelli, cephalic glands, and well-developed protonephridia. Typical of cercariae is the development of a tail, which is sometimes bifurcate (in furcocercariae) or equipped with lateral appendages.

The cercaria develops inside the preceding larval form, the sporocyst or redia, as a result of parthenogenesis. It leaves the body of the first intermediate host, a mollusk, and swims in water by means of its tail. It then penetrates the body of the second intermediate host, an invertebrate or frequently a fish, and becomes a metacercaria. The common liver fluke has no second intermediate host; the cercaria becomes encysted on coastal vegetation and is transformed into the next larval form, adolescarium.

References in periodicals archive ?
w], the time between cercarial penetration to the mature worm, are all biologic parameters.
This provides a crude measure of the spatial variation in cercarial concentration.
However, there are some cercarial bioassay data that might allow a crude rank ordering of infected snail density by village.
z] Sporocyst development delay to 60-83 cercarial release (days) [[mu].
Cercarial dermatitis (swimmer's itch) is caused by penetration of human skin with cercariae of schistosome parasites; the condition is common and recurrent in freshwater habitats worldwide.
A cercarial dermatitis outbreak in San Francisco Bay was reported in 1954 (1).
dermatitis were reported in San Francisco Bay or elsewhere on the Pacific Coast until the summer of 2001 when 36 cases of cercarial dermatitis were reported at Crescent Beach in Surrey, British Columbia, Canada; 44 cases were reported in 2002 (20).
In June 2005, cercarial dermatitis appeared again in San Francisco Bay.
Snails were isolated singly or in groups of 5 in plastic containers in saline water (20-35 parts per thousand [ppt]) and placed in natural light to induce cercarial shedding.
hematobium, Schistosoma haematobium; CDA, cercarial dermatitis, asymptomatic.
Indirect tests for schistosomiasis rely on detection of circulating antibodies to egg, cercarial or adult schistosomes.
Schistosomiasis is transmitted through contact with infected water when the cercarial larvae penetrate skin, and increasing evidence exists that M.