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Centers for Disease Control/Division of Parasitic Diseases and Malaria
EOL staff
Life cycle of the Broad Tapeworm (Diphyllobothrium latum) Immature eggs of the Broad Tapeworm (Diphyllobothrium latum) are passed in feces (1) from the definitive host. Under appropriate conditions, the eggs mature (after approximately 18 to 20 days) (2) and yield oncospheres, which develop into a coracidia (3). After ingestion by a suitable freshwater crustacean (the copepod first intermediate host), the coracidia develop into procercoid larvae (4). Following ingestion of the copepod by a suitable second intermediate host, typically minnows and other small freshwater fish, the procercoid larvae are released from the crustacean and migrate into the fish flesh, where they develop into a plerocercoid larva (sparganum) (5). The plerocercoid larvae are the infective stage for humans. Because humans do not generally eat undercooked minnows ans similar freshwater fish, these do not represent an important source of infection. Nevertheless, these small second intermediate hosts can be eaten by larger predator species such as trout, perch, and walleyed pike (6). In this case, the sparganum can migrate to the musculature of the larger predator fish and humans can acquire the disease by eating these later intermediate infected host fish raw or undercooked (7). After ingestion of the infected fish, the plerocercoid develop into immature adults and then into mature adult tapeworms, which will reside in the human host's small intestine. The adults of D. latum attach to the intestinal mucosa by means of the two bilateral grooves (bothria) of the scolex (8). The adult tapeworms can exceed 10 m in length, with more than 3,000 proglottids. Immature eggs are discharged from the proglottids (up to 1,000,000 eggs per day per worm) (9) and are passed in the feces (1). Eggs appear in the feces 5 to 6 weeks after infection. In addition to humans, many other mammals can also serve as definitive hosts for D. latum. From
Centers for Disease Control Parasites and Health website.
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Figure 5.Alaria chengguanensis sp. n., male holotype (A–B) and female paratype (C–D). A Pedipalp, prolateral view B Embolic division, dorsal view C Epigyne, ventral view D Vulva, dorsal view. CD copulatory duct; Co conductor; MA median apophysis; S spermatheca. Scale bars: D as C.
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Carolina Noreña, Daniel Marquina, Jacinto Perez, Bruno Almon
Zookeys
Figure 4.Prostheceraeus vittatus. A dorsal view of a living animal B living animal feeding on ascidians C dorsal view of a fixed specimen D sagittal reconstruction of the copulatory apparatus E sagittal reconstruction of a whole specimen. Anterior to the left in D, E.
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Giacinta Angela Stocchino, Ronald Sluys, Renata Manconi
Zookeys
Figure 5.Dugesia bifida. Microphotographs of the copulatory apparatus. A Holotype ZMA V.Pl. 7189.1, sagittal section showing the penis bulb (pb) and the penis papilla (pp) with the seminal vesicle (sv) and the ejaculatory duct (ed) B Holotype ZMA V.Pl. 7189.1, sagittal section showing the opening of the right oviducal branch (rob) through the posterior wall of the bursal canal (bc), and the common posterior oviducal extension (cpe) full of sperm (s) C Paratype CGAS Pla 7.1, sagittal section showing the caudal part of the common posterior oviducal extension (cpe) and the ductule (du) communicating with the ventral part of an adjacent vitellarium (v).
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Carcharodopharynx arcanus, a very rare and unusual Dalytyphloplanoid from periodically inundated forest soils near Kloech, Austria.
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South Pacific Ocean, Shot at night, Duration 26 seconds
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Coral Sea, Shot at night, Duration 47 seconds
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Hampen Sø, Midtjylland, Danmark
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Roskilde
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Kastbjerg Å
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Gudenå opstrøms Klostermølle, Mattrup Å ved Stidsmølle
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Ørn Sø, Silkeborg, Danmark
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Dollerup Kilde ved Hald Sø, Jylland, Danmark
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Centers for Disease Control/Division of Parasitic Diseases and Malaria
EOL staff
Life cycle of Echinostoma trematode flatworms, the agents causing echinostomiasis in humans Many animals may serve as definitive hosts for various Echinostoma species, including aquatic birds, carnivores, rodents, and humans (a definitive host is the host in which the adult parasites occur). Unembryonated eggs are passed in feces (1) and develop in the water (2). On average, the ciliated
miracidium larva takes around 10 days to mature before hatching (3) and penetrating the first intermediate host, a snail (4). Several genera of snails may serve as the first intermediate host. The intramolluscan stages include a
sporocyst (4a), one or two generations of
rediae (4b), and
cercariae (4c). The
cercariae may encyst as
metacercariae within the same first intermediate host or leave the host and penetrate a new second intermediate host (5). Depending on the species, a range of animals may serve as the second intermediate host, including other snails, bivalve mollusks, fish, and tadpoles. The definitive host becomes infected after eating a second intermediate host (6).
Metacercariae excyst in the duodenum (7) and adults reside in the small intestine (8) of the definitive host.From
Centers for Disease Control Parasites and Health website.
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Carolina Noreña, Daniel Marquina, Jacinto Perez, Bruno Almon
Zookeys
Figure 5.Prostheceraeus moseleyi. A, B, C dorsal views of living animals D sagittal reconstruction of the reproductive system E dorso-ventral histological sections of the whole animal F dorso-ventral histological sections of the copulatory apparatus G sagittal histological section in the region of the pharynx and copulatory apparatus H sagittal reconstruction of a whole specimen. Anterior to the right in C, D, E, F, G and H.
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Giacinta Angela Stocchino, Ronald Sluys, Renata Manconi
Zookeys
Figure 6.Dugesia bifida. A Holotype ZMA V.Pl. 7189.1, microphotograph of the right hyperplasic ovary (o) with the tuba (tu) B Paratype CGAS Pla 7.1, microphotograph of the oviduct (od) with an expansion (ov) C Holotype ZMA V.Pl. 7189.1, microphotograph of mature testes (t) with sperm (s).
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Carcharodopharynx arcanus, a very rare and unusual Dalytyphloplanoid from periodically inundated forest soils near Kloech, Austria.
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Coral Sea, Shot at night, Duration 8 seconds
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Hampen Sø, Midtjylland, Danmark
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Roskilde
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Kastbjerg Å
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Gudenå opstrøms Klostermølle, Mattrup Å ved Stidsmølle
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Ørn Sø, Silkeborg, Danmark
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Dollerup Kilde ved Haldsø