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Topic: Cercariae

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	Schistosomiasis
		Once it has found its snail host, the miracidium divides, producing thousands of new parasites (cercariae).
		The cercariae are then excreted by the snail into the surrounding water.
		They can penetrate an individual's skin within a few seconds, continuing their biological cycle once they have made their way to the victim's blood vessels.
	www.tulane.edu /~dmsander/WWW/224/Schisto.html (1427 words)

	eMedicine - Schistosomiasis : Article Excerpt by: Palaniandy Kogulan, MD
		The cercariae leave the snail and swim to a human or nonhuman animal, where they penetrate the skin.
		Once inside, cercariae travel to the heart, the lungs, and through the systemic circulation to reach the portal veins where they develop into adult worms.
		Schistosomula: These are tailless cercariae that are transported through blood or lymphatics to the right side of the heart and lungs.
	www.emedicine.com /med/byname/schistosomiasis.htm (611 words)

	The Schistosome Cercaria
		Cercaria are the larval form of the parasite liberated from the snail intermediate host for all Trematode parasites.
		The cercaria of schistosomes are characterised by having long tails which are bifurcated at the end (the furcal rami).
		Cercaria can remain infective, under optimal conditions, for between 5 to 8 hours after shedding, although in the field this is probably much less, due to such factors as variation in water temperature.
	www.path.cam.ac.uk /~schisto/SchistoLife/Cercaria.html (344 words)

	Memórias do Instituto Oswaldo Cruz - Ultrastructure and chaetotaxy of sensory eeceptors in the cercaria of a species ... (Site not responding. Last check: )
		Cercariae were treated with acetylthiocholine iodide and silver nitrate, and some were processed for light, scanning (SEM), and transmission (TEM) electron microscopy.
		The mechanoreception of sensory receptors in the cercaria of Allopodocotyle sp.
		This cotylomicrocercous cercaria crawls with the aid of both suckers to find a host, eventually attaching to the substratum with its glandular tail and then wagging the anterior end of its body back and forth until a suitable host is contacted (Hunninen and Cable 1943, Lo et al.
	www.scielo.br /scielo.php?script=sci_arttext&pid=S0074-02762001000200012 (4050 words)

	BioMed Central \| Full text \| A study on cercarial dermatitis in Khuzestan province, south western Iran
		To obtain cercariae, Lymnaea snails were examined for shedding cercariae by using artificial light or leaving over night or by crushing methods by removing the snails and crushing them against a glass plate.
		Cercariae were collected and fixed in 5% hot formaldehyde and cleared in lactophenol or stained with azocarmine.
		Cercariae of animal schistosomes could be confused with strigeid cercariae, however, the former lack a pharynx.
	www.biomedcentral.com /1471-2458/3/35 (0 words)

	Untitled Document (Site not responding. Last check: )
		Cercariae are light sensitive and are released from snails especially in the early morning.
		In addition to thermotactile stimulation, cercariae follow non-selective chemoattractants such ceramide and cholesterol, which facilitate the sticking of the cercariae on the host's skin.
		They penetrate the stratum corneum (this is facilitated by the release of proteolytic enzymes), and die within a few hours in the epidermis.
	www.stanford.edu /class/humbio103/ParaSites2006/Cercarial_Dermatitis/lifecycle.htm (236 words)

	Parasites, infections and diseases of fishes in Africa: An update
		Cercariae may also have locomotive devices; a tail, in some forked, fins (the forked-tailed cercariae of sanguinicoliids also have a characteristic dorso-median fin fold), and a pair of eyes.
		Cercariae are fork tailed with a dorso-median fin fold (similar to that seen in sanguinicolid cercariae).
		Cercariae penetrated and encysted deeper in the tissues of small fish and the large cysts interfered with organ function.
	www.fao.org /docrep/008/v9551e/V9551E14.htm (6396 words)

	Brazilian Journal of Medical and Biological Research - Ultrastructural and biochemical detection of biotin and ... (Site not responding. Last check: )
		Cercariae, cercarial bodies and adult male worms were examined by transmission electron microscopy employing an avidin-colloidal gold conjugate for the detection of endogenous biotin.
		In the cercariae, gold particles were mainly distributed on muscle fibers (Figure 2a), but dispersed granules were observed in the tegument and mitochondria (Figure 2c).
		The bands from cercarial bodies and tails obtained from labeled cercariae did not differ from those obtained from unlabeled samples, suggesting the loss of cercarial surface polypeptides from the glycocalyx during the isolation of bodies and tails, since many other bands were seen in the whole labeled cercariae.
	www.scielo.br /scielo.php?script=sci_arttext&pid=S0100-879X1997000700003 (2180 words)

	Schistosomiasis Summary
		The cercariae, which survive outside a host for 48 hours, quickly penetrate unbroken skin, the lining of the mouth, or the gastrointestinal tract.
		Cercariae emerge daily from the snail host in a circadian rhythm, dependent on ambient temperature and light.
		Young cercariae are highly motile, alternating between vigorous upward movement and sinking to maintain their position in the water.
	www.bookrags.com /Schistosomiasis (3816 words)

	Cercarial dermatitis - Page 2
		Cercarial dermatitis (swimmer's itch) is a cutaneous inflammatory response usually associated with penetration of the skin by cercariae of bird schistosomes.
		This is an indication of initial penetration of the cercariae.
		The cercariae then must be identified as being a type that can cause cercarial dermatitis by using appropriate reference material.
	www.dpd.cdc.gov /dpdx/HTML/Frames/A-F/CercarialDermatitis/body_CercarialDermatitis_page2.htm (246 words)

	NIAID Schistosomiasis Resource Center
		Cercariae that emerge can be seen in the water using a dissecting microscope.
		mansoni cercariae are placed in a 12-mm x 75-mm glass or plastic test tube and conditioned water added to within 10-mm from the top of the tube.
		Thus, S. japonicum cercariae are usually placed on the abdomen using a small hair-loop connected to the end of a Pasteur pipette.
	www.schisto-resource.org /sop.htm (1766 words)

	Larval Trematoda: Winterbourne
		Cercariae are very active compared with other monostome species found, swimming being accompianied by strong contractions of both body and tail.
		Cercariae swim actively by thrashing movements of the tail which is held vertically above the body.
		Cercariae were found in 13 collections and in 12 of these monostome species were present.
	www.indiana.edu /~curtweb/trematodes/Winterbourne.htm (2158 words)

	statistics (Site not responding. Last check: )
		Cercariae from some species of nonhuman schistosomes are attracted to light and will concentrate at the surface of the water.
		The reason appears to lie in the fact that the free-swimming stage (cercaria) of some schistosome species float to the surface of the water and drift with the wind to the shore.
		Floating cercariae of some species of schistosomes are sticky and attach to the body as the bather leaves the water.
	www.horseheadlake.org /itch.html (3351 words)

	[No title]
		For cercariae in the water, this structure is absolutely es-sential, but after penetration into a host it could be a source of possible activation of host immune system.
		However, changes in glycosylation of cercariae and fol-lowing post-penetration stages seem to be a good marker of transformation not only for schistosomes but also for other host-penetrating species.
		Cercariae of trematodes (Digenea) from fresh-water molluscs in South-Eastern Germany: a comparison with the Czech Republic A.
	www.saske.sk /pau/helminthologia/HDays05.doc (7682 words)

	Fauna of Trematodes - Lymnaea stagnalis
		The cercaria hang motionless with their bodies bent in the water and let themselves be carried along by the current, interrupted only by short and fast swimming movements.
		The two suckers of the cercariae are approximately the same size, the intestinal system is strongly developed, and the intestinal branches almost reach the end of the body.
		The cercariae which stream out of the sporocysts are active swimmers, that often stay at the surface of the water, but they can also crawl about the water bed.
	www.uni-bielefeld.de /biologie/Didaktik/Zoologie/html_eng/galerie_Ls_eng.html (1637 words)

	Bioline International Official Site (site up-dated regularly)
		In sporocyst and cercariae stages, partially entire larvae were found, enclosed by granulomas, in the cephalic area, in the kidney and among the lobules of the digestive gland.
		Partially degenerated cercariae were found, enclosed by granulomas, in the cephalic area, in the mantle, in the tentacles, in the wall of the palial cavity and in the pseudobranchias.
		Sporocysts II containing agglomerated germinative cells with covering membrane and cercariae in different development stages were found close to the oesophagus, to the stomach, to the intestine, in the gland of the albumen, in the seminal vesicle, and among the lobules of the digestive gland and of the ovitestis.
	www.bioline.org.br /request?oc01118 (7021 words)

	U of M - 22.346 Lab (Site not responding. Last check: )
		The first readia generation leaves the sporocyst and enters the liver of the snail where the next two redial generations are produced with the third one producing cercariae.
		Cercariae are released and are positively phototropic and swim about until they contact a frog or a tadpole.
		When this happens the cercariae will encyst on the viscera of the tadpole, then rapidly excyst and move to the rectum.
	www.umanitoba.ca /faculties/science/zoology/faculty/dick/z346/diplohome.html (201 words)

	In vitro encystment of echinostomatid cercariae
		The cercaria mortality after 24 h in the whole hemolymph was twice higher than in plasma (40% and 20%, respectively) and much higher than in the control medium (sea water).
		There is shown both the strong individual variability of toxicity of the individual mussel hemolymph for cercariae and the variability of the resistance to the toxic factors of the cercariae obtained from various L. littorea individuals.
		Gorbushin, A., Levakin, I. 2005 Encystment in vitro of the Cercariae Himasthla elongata (Trematoda: Echinostomatidae).
	www.angelfire.com /sc/gorbushin/encystment.html (0 words)

	Swimmer's Itch - Upper Hay Lake Association
		Any attempts to control swimmer’s itch by treatment to kill either the cercariae or their snail hosts are ineffective because cercariae are capable of swimming or drifting long distances from non-treated areas.
		Immature larval forms (cercariae), of parasitic flatworms (schistosomes), are released from infected snails into fresh and salt water, such as lakes, ponds, and lagoons.
		When cercariae contact a suitable bird or mammal, they penetrate through the skin, migrate through various organs such as the liver and lungs, and then reside in the blood vessels of the host, particularly those surrounding the intestine.
	www.mnlakes.org /SubAssociations/index.cfm?ID=2084&NAV=1177 (2296 words)

	Swimmer’s Itch
		It is the penetration of those cercariae through the skin of bathers which results in swimmer’s itch.
		Man is an accidental host, and had the cercariae found their natural host, they would complete their life cycle to adult form.
		As the cercariae penetrate the skin, a temporary, prickly, itching sensation occurs, sometimes followed by a general inflammation of the affected area.
	www.publichealthgreybruce.on.ca /Water/BeachSafety/Swimmers_ItchFS.html (448 words)

	Digenea -- Encylopedic Reference of Parasitology
		Cercariae of many digeneans find and recognize their hosts with complex behavior patterns and via very different, highly sensitive and specific receptors.
		For example, cercariae of human schistosomes accumulate in the uppermost water layers, whereas parasites of ground-dwelling invertebrates orientate towards the bottom of waters, and some of them select microhabitats there with a defined light intensity.
		The cercariae shift to a high swimming activity, which leads them upward in the water column, and this may increase the chance for an encounter with their human hosts.
	parasitology.informatik.uni-wuerzburg.de /login/n/h/0387.html (0 words)

	Hope College ~ Swimmer's Itch ~
		When cercariae contact a suitable bird or mammal, they penetrate through the skin, migrate through various organs such as the liver and lungs, and then reside in the blood vessels of the host, particularly those surrounding the intestine.
		If the cycle can be reared in the laboratory, cercariae from the lab cultures can be compared to those that emerge from naturally-infected snails taken from areas on the lake where swimmer's itch was a problem.
		Furthermore, the cercariae from the species of schistosomes that cycle through common mergansers, are much larger than average and emerge only from lymnaeid snails, particularly Stagnicola emarginata.
	www.swimmersitch.org /faq.html (0 words)

	Lakes Page - Topic - Swimmer's Itch, Maine DEP
		Cercariae penetrate the skin of bathers as water droplets dry.
		The miracidia penetrate snails and further develop into cercariae, minute free-swimming, fork-tailed colorless animals that are then released by the snails.
		If cercariae are on the skin they will try to penetrate the moment you emerge from the water.
	www.maine.gov /dep/blwq/doclake/itch.htm (379 words)

	PARASITES in the Human Body
		Infection occurs through contact with fresh water that contains infective cercariae released from an intermediate host snail.
		The cercaria penetrates intact human skin and transforms into the migrating schistosomulum larva, that migrates through the bloodstream to the hepatic portal system to complete the parasites lifecycle.
		Penetration of the skin by the cercaria (usually from species unable to develop in man, particularly cercaria of species of avian schistosomes) may result in a form of dermatitis, cercarial dermatitis, though this is not as important in terms of pathology as egg induced pathology, (see below).
	www.savedrclark.net /parasites.htm (1054 words)

	Dr. Ramaswamy's Presentation
		Skin is the only known route of entry for this parasite into humans and the infective stage of the parasite, called cercariae, can penetrate intact skin within minutes after water contact.
		Another disease condition called "swimmer's itch" or "cercarial dermatitis" is caused by inadvertent entry of the cercariae of animal schistosome (for example Trichobilharzia ocellata - a bird schistosome) into the human skin resulting in severe dermatitis.
		During the last 30-40 years several chemical compounds were screened by different laboratories for their ability to confer protection against cercarial penetration.
	www.deet.com /astmh/Swamy.html (0 words)

	Echinostomatid cercariae and metacercariae in Bithynia tentaculata in lake Zhuvintas and the Nyamunas delta (Site not responding. Last check: )
		Echinostomatid cercariae and metacercariae in Bithynia tentaculata in lake Zhuvintas and the Nyamunas delta
		Four cercariae species were identified in Bithynia tentaculata in Lake Zhuvintas and the Nyamunas delta, Lithuanian SSR.
		I (synonym of Cercaria helvetica and Sphaeridiotrema globulus) and Petasiger sp.
	trophort.com /000/344/000344606.html (100 words)

	DNR - Verminous Hemorrhagic Ulcerative Enteritis (Site not responding. Last check: )
		When fully mature the cercariae leave the rediae by the birth port and escape from the snail through its anal opening.
		When contact is made with the exposed surface of one of these snails, the cercariae creep along randomly on the foot, head, and mantle.
		When the edge of the mantle is reached, the cercariae penetrate the columellar muscle between the mantle and the shell and become encysted.
	www.michigan.gov /dnr/0,1607,7-153-10370_12150_12220-27317--,00.html (1091 words)

	Abstract 30
		Attenuation of Schistosoma mansoni cercaria with a molluscicide and cercaricide derived from the Egyptian weed, Solanum nigrum L. Hanan HELMY
		Cercariae were exposed to 5, 10, 15 and 20 ppm of the extract for 30 minutes, immediately before mice infection to quantify the effect of varying levels of exposure to FLWE on the activity of cercariae and its capacity to generate adult worms in mice.
		BALB/c mice exposed to treated cercariae produced IgM and IgG antibody responses that were estimated by ELISA using cercarial and adult worm antigen preparations.
	www.naturalhistorymuseum.org.uk /hosted_sites/schisto/prcschisto/abst/abst30.html (383 words)

	[No title]
		Cercariae penetrate the skin of humans or, in the case of S. japonicum, humans and other mammalian hosts that act as reservoirs for infection.
		The cercariae shed their bifurcated tails, and the resulting schistosomula enter capillaries and lymphatic vessels en route to the lungs.
		After further development in the snail in the form of sporocysts, a very large number of larvae each with a bifurcated tail, known as cercariae, is released.
	www.itg.be /itg/DistanceLearning/LectureNotesVandenEndenE/Teksten/sylabus/40_Schistosomiasis.doc (8814 words)

	CJO - Abstract
		It was shown that cercariae were carried in respiratory currents into crabs' branchial chambers where each enveloped itself in a transparent penetration cyst on the gill lamellae.
		When cercariae were present the number of respiratory current reversals performed by crabs increased.
		The importance of crab respiratory current reversals to the success of cercarial penetration is discussed as it represents the exploitation by a parasite of a host behavioural response to an unrelated stimulus.
	journals.cambridge.org /production/action/cjoGetFulltext?fulltextid=335829 (246 words)

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