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41 terms

Parasitology Set IV

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What stage in the life cycle of trematodes is pyriform and must find a suitable snail within a few hours of erupting from the egg?
Miracidium
What stage in the life cycle of trematodes is a non-ciliated elongated sac found in the snails' tissues?
Sporocyst
What stage in the life cycle of trematodes develops from germinal cells in the sporocysts inside the snail's tissue?
Rediae
What stage in the life cycle of trematodes have long tails and penetrate the skin of the mammalian host or encyst on vegetation?
Cercarie
What stage in the life cycle of the trematodes is an encysted cercarie attached to vegetation or in the second intermediate host and is the infective stage for the definitive host?
Metacercariae
What is the DH and IH for Fasciola hepatica?
DH: mammals (sheep and cattle most important)
IH: mud snails (Lymnea spp.)
How are the definitive hosts of F. hepatica infected?
Ingest metacercariae encysted on vegetation
Where are the adults of F. hepatica found in the DH?
Migrate through liver, stay in bile ducts
What are the different forms of ovine fasciolosis infection?
Acute fluke disease
Subacute disease
Chronic fasciolosis
In which animals does F. hepatica cause calcification of the bile ducts (pipestem fibrosis)?
Cattle
How is F. hepatica infestation diagnosed?
Fluke eggs (sedimentation technique)
Routine hematological tests
ELISA
Passive hemagglutination test
What is the DH and IH of Fascioloides magna?
DH: Deer and other wild ruminants
IH: Snail (Lymnea spp.)
In which animals are the eggs of Fascioloides magna seen?
Deer only
What is the DH and IH of Paramphistomun spp.?
DH: Ruminants
IH: Water snails (Physa, Bulinus, Galba, and Pseudosccinea spp.)
Where are Paramphistomun spp. found in the DH?
Duodenum and then the rumen and reticulum
How are the DH of Paramphistomun spp. infected?
Ingest vegetation with encysted metacercariae attached
How is a Paramphistomun spp. infestation diagnosed?
Clinical signs
Postmortem examination
Small flukes recovered from duodenum
What are the DH and IH of Dicrocoelium dendriticum?
DH: Sheep, cattle, deer, wapiti, and rabbit
1st IH: Land snails
2nd IH: Brown ants (Formica fusca)
Where are the adult Dicrocoelium dendtriticum found in the DH?
Bile ducts
Gall bladder
Pancreatic ducts
How is a Dicrocoelium dendriticum infestation diagnosed?
Fecal examination of eggs
Necropsy
What is the DH and IH of Schistosoma spp.?
DH: All domestic mammals and humans (sheep and cattle)
IH: Water snails (Bulinus and Physopsis spp.)
Where are adult Schistosoma spp. generally found in the DH host?
Blood vessels of the alimentary tract and bladder
How are the definitive host of Schistosoma spp. infected?
Cercariae penetrate the final host via the skin or ingestion of drinking water
How is a Schistosoma infestation diagnosed?
Eggs in feces
Postmortem
Serological tests
What is the DH and IH of Heterobilharzia americana?
DH: Raccoon, nutria, bobcat, rabbit, and dogs
IH: freshwater snail (Lymnea cubensis)
Where are Heterobilharzia americana adults found in the DH?
Lungs and liver
How are the definitive host of Heterobilharzia americana infected?
Cercariae penetrate the skin
Mesenteric veins
What is the DH and IH of Nanophyetus salmincola?
DH: carnivores of the Pacific Northwest
1st IH: Freshwater snail (Oxytrema silicula)
2nd IH: Salmonid fish
How is the definitive host of Nanophyetus salmincola infected?
Eating salmon containing metacercariae
What parasite is host to a rickettsial agent (Neorickettsia helminthoeca) responsible for "salmon poisoning" in dogs?
Nanophyetus salmincola
What is the DH and IH of Paragonimus kellicottti?
DH: Cats, dogs, and many wild mammals
1st IH: Snail (Pomatiopsis lapidaria)
2nd IH: Crayfish
How are the definitive host of Paragonimus kellicotti infected?
Ingesting crayfish containing metacercariae
Where in the definitive host are the adults of Paragonimus kellicotti found?
Pulmonary cysts in lungs
How is a Paragonimus kellicotti infestation diagnosed?
"Signet rings" on radiographs
Clinical signs
What is the DH and IH of Alaria spp.?
DH: Dogs, cats, fox, and mink
1st IH: Freshwater snail (Helisoma)
2nd IH: Tadpole
Paratenic host: frog, snake, mouse...
Where in the definitive host are adult Alaria spp. found?
Smal intestine
How does the definitive host become infected with Alaria spp.?
Eating frogs containing encysted metacercariae
What is the DH and IH of Macracanthorhynchus hirudinaceus?
DH: Swine
IH: June bugs, Dung and water beetles
How are the definitive host of Macracanthorhynchus hirudinaceus infected?
Pigs rooting around for beetle grubs containing cystacanth stage
Where in the definitive host are the adults of Macracanthorhynchus hirudinaceus found?
Small intestine
How is a Macracanthorhynchus hirudinaceus infestation diagnosed?
Eggs in feces using a sedimentation technique