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25 Cards in this Set
- Front
- Back
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Classes of Platyhelminthes |
Turbellarians - free-living carnivores Cestodes - tapeworms Trematodes - flukes |
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Orders of Trematodes |
Monogenia - ectoparasites of aquatic animals Digenea - tissue- or blood-dwelling endoparasites |
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Monogenia |
Order of Trematodes - ectoparasites of aquatic animals - hermaphrodites - direct life cycle - viviparous - feed on epidermis, blood, mucus - Gyrodactylus spp and Dactylogyrus spp |
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Gyrodactylus spp |
- Trematoda Monogenia - Ectoparasites on skin and gills of aquatic animals - Haptor for attachment - Treated with praziquantel, but hard to get rid of |
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Digenea |
- Order of Trematodes - Most are hermaphrodites - Oral and ventral suckers - Intermediate hosts w/ indirect development - Alternate b/w sexual (in definitive host) and asexual (in the intermediate) reproduction - Snail is intermediate host for all these hosts |
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Digenea Life Cycle |
- Eggs in water hatch into miracidium - Infect snails --> develop into sporocysts then redia or daughter sporocysts --> asexual reproduction --> release cercaria - Cercaria swim around and form metacercaria in vegetation or second intermediate host then ingested by definitive host OR directly penetrate - Reproduce sexually --> eggs |
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How Digenea Enter Definitive Hosts |
- Eat metacercariae encysted on vegetation - Eat infected secondary host --- aquatic animals, arthropods, amphibia - Direct penetration of skin by larval cercaria |
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Fasciola hepatica |
- Platyhelminthes Trematoda Digenea - Liver fluke that encysts on vegetation - Large, operculate, unembryonated eggs in feces - Diagnostic stage = eggs in feces - Definitive Host = sheep, cattle, humans (zoonotic) |
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Fasciola hepatica Life Cycle |
- Unembryonated egg in feces of sheep, cattle, human - Develops into miracidium, infects snail - Develops into sporocyst then redia in snail, asexual reproduction to cercaria and released - Cercaria encyst on vegetation as metacercaria - Ingested, encyst in duodenum, penetrates intestinal wall then in abdominal cavity and penetrates liver. (3-4 months overall) |
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Pathogenesis of Fasciola hepatica Acute Disease |
- Due to ingestion of large #s of metacercaria - Juveniles tunneling in liver result in thrombi and coagulative necrosis - Secondary Clostridium novyi in these liver lesions leading to necrosis, hemorrhage, death - Adults reside in bile duct and feed on blood, cause bile duct hyperplasia, anemia |
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Pathogenesis of Fasciola hepatica Chronic Disease |
- F. hepatica lives in bile duct, causes hyperplasia, fibrosis, and calcification - See hyperproteinemia, anemia, wasting disease - Weight loss! Bottle jow, ascites, emaciation |
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Fasciola hepatica Treatment |
- Treat adults (when environment is not conducive to egg survival: hot/dry or cold) - Albendazole, triclabendazole, clorsulon - Mulluscicide - Move to fluke-free pastures |
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Fascioloides magna |
- Platyhelminthes Trematoda Digenea - Definitive host: deer - Form cysts in liver that connect to bile duct - Can infect sheep/goats and do not mature, so juveniles stay in liver - No eggs in the aberrant hosts, so no eggs to diagnose |
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Paraphyistomatidea |
- Typical trematode lifecycle, encyst on vegetation - Patent in sheep, cattle, deer - Adults harmless. Pear-shaped with oral, ventral suckers - High infective dose - get disease due to parasites migrating from small intestine to rumen - Eggs often confused with Fasciola hepatica |
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Nanophyetus salmincola |
- Platyhelminthes Trematoda Digenea - Intestinal fluke - Metacercaria on salmonids (fish eaten by definitive host) - Diagnose by eggs in stool - These flukes carry Neorickestsia helminthoeca which is pathogenic for salmon |
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Paragonimus kellicotti |
- Platyhelminthes Trematoda Digenea - Lung fluke, found as pairs - Cause respiratory disease from migration in lungs - Metacercaria in crustateans (fish eaten by definitive host - often dogs) - Eggs are coughed out of lungs - either in mucus or swallowed and released in feces - Eggs is operculate with collar-like structure |
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Platynosomum fastosum |
- Platyhelminthes Trematoda Digenea - Liver fluke of cats in SW US and West Indies - Metacercariae in amphibians, lizards, geckos |
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Alaria spp. |
- Platyhelminthes Trematoda Digenea - Many definitive hosts - often wildlife - Vertical transmission via milk - Cercaria infect tadpoles, form Mesocercaria - Eaten by definitive host or paratenic host - Mesocercaria in lungs of definitive host form metacercaria, coughed, swallowed, mature to adults in gut - IF lactating, metacercaria instead formed in mammary glands. |
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Dicrocoelium dentriticum |
- Platyhelminthes Trematoda Digenea - Definitive host: sheep, cattle, pigs - bile duct - Terrestrial life cycle. Slimeball released by snail with cercaria, ant attracted to it - form metacercaria in ants. They climb up to top of grass to be eaten by sheep - Small worms, operculate eggs, lancet-shaped - Clinical disease: bile duct fibrosis & cirrhosis |
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Schistosoma japonicum |
- Platyhelminthes Trematoda Digenea - Definitive host: humans - zoonotic, water buffalo - Percutaneous route of infection - Two sexes. - Live in vasculature near liver, migrate to gut, expelled in feces, infect snail, cercariae = infective - Eggs cause chronic disease by lodging in tissues and forming granulomas |
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Heterobilharzia americana |
- Platyhelminthes Trematoda Digenea - Definitive host: dogs, raccoons, rabbits - Percutaneous route of infection - Predilection site: mesenteric veins. - Usually asymptomatic, but eggs evoke granulomatous response |
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Swimmer's Itch |
Avian schistosome infection (Digenea trematode with percutaneous route of infection) - The cercariae die after skin penetration - Delayed-type hypersensitivity reaction |
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Acanthocephalans |
- Thorny head worms - Separate sexes - No gut - High reproductive output - Male cement glands to seal female vagina after copulation |
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Acanthocephalans Life Cycle |
- Sexual reproduction in vertebrate host, make eggs, released in feces. - Egg ingested by invertebrate. - Larval form in egg (Acanthor) hatches and forms Acanthella. - Acanthella migrates and forms a cystacanth - Ingested by vertebrate. - Cystacanth encysts and gives rise to adults. |
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Macracanthorhynchus hirudinaceus |
- Acanthocephalan - Small intestine of pigs, sometimes dogs - Intermediate host = beetles - Not generally important in N. America (pigs raised on concrete). Treat w/ ivermectin. - Highly pathogenic. Necrosis at local site, ulceration and granulomas, competition for nutrients leads to wasting. - Eggs in feces diagnostic. Thick, brown shell. |
