Trematodes And Cestodes Flashcards
What group of animals are the final and intermediate hosts of digenetic trematodes
Vertebrate final host
Mollusk intermediate host - snail
Characteristics of digametic trematodes
Covered with syncytium
Typically hermaphroditic
2 suckers, anterior and a posterior
All lay eggs
What developmental stages found in the snail
Sporocysts
Daughter sporocysts
Redia
Cercaria (infective to vertebral host)
Characterize trematodes transmission
With exception of schistosomes, all transmission of trematodes is via ingestion of the Cercaria stage
Which flukes are transmitted via ingestion of vegetation
Fasciolopsis buski - giant intestinal fluke
Fasciola hepatica - sheep liver fluke
Fascioloides magna
Peramphistomes
What are the vertebrate hosts of Fasciolopsis buski
Pigs and humans (small intestine)
How are people infected and affected by Fasciolopsis buski
Peeling water chestnuts and buffalo nuts with their teeth - ingest metacercarial cyst
Usually no damage with small infections… May see edema of face, intestinal obstruction
In what specific site are Fasciola hepatica found
Bile duct of sheep and cattle
What causes disease in Fasciola hepatica infection
Larvae leave ingesting, come out through wall, burrow through liver to get to bile duct
Distinguishing feature about Fasciola hepatica cercaria
They have a tail
What site specific place are Fascioloides magna found I
Cysts in liver of white tailed deer
How do Fascioloides magna affect sheep cattle and bison
Sheep - leave dark pigment when destroying liver
Cattle - do not find eggs in feces
Bison - refractory to infection
How do peramphosomes cause pathology
Immature flukes burrow into wall of small intestine effort making their way back to the rumen where they live (or cecum/colon in hind gut fermenters)
Which trematodes are transmitted via ingestion of insects
Dicrocoelium dendriticum - lanceolate liver fluke
Eurytrema pancreaticum/procyonis
What vertebrates can Dicrocoelium dendriticum be found in, and in what organ
What insect must be ingested
Sheep, deer, woodchucks, cattle, pigs
Bile duct
Ants
What age range of animals are pathological with Dicrocoelium dendriticum infection
Older animals, must be within animals for a ling time to see pathology
Which trematodes are transmitted via consumption of crayfish and crabs
Paragonimus kellicotti
In what hosts and where within the hosts do Paragonimus kellicotti live
Mink and bobcats naturally, also can infect dogs and cats
Live in cysts in the lungs (larva migrate straight throughout diaphragm to lungs)
Which trematodes transmitted via ingestion of fish
Nanophyetus samlincola
Clonorchis sinensis
Opisthorchis
Metorchis
What hosts are adult Nanophyetus salmincola found in
Bear raccoon coyote mink other canids
What agent does Nanophyetus salmincola vector and what is the associated disease
Nerickettsia helminthoeca
Mostly fatal diarrhea and vomiting in dogs
What fish are sources of Nanophyetus salmincola
Rainbow trout and steelhead trout
What is the common name for Clonorchis sinensis
Oriental liver fluke
What are common vertebrate hosts of the oriental liver fluke
People in Asia, dogs
What is the vertebrate host of metorchis conjunctus
Cat, in bile duct
How is platynosum fastosum transmitted
What are the host and specific site within the host
Ingestion of lizards or frogs
Found I bile ducts or gall bladder of cats in the tropics
Alaria species are transmitted via various paratenic hosts. What are their vertebrate final hosts
Fox, raccoon, skunk, dog, cat
Live in intestine
What is another way to transmit Alaria besides ingestion of paratenic host
Passed through milk of cat
What stage of Alaria causes disease
Larva
How are hosts infected with schistosomatidae
Skin penetration
What does the name schistosomes imply?
Split bodies,… Separate males and females
What is the scientific name for the America schistosomes and how does it cause disease
Heterobilharzia americana
Adults live in veins but, Eggs carried to liver causing fibrosis
Why use saline when looking for the human parasite, Schistosoma mansoni
Eggs spontaneously hatch in fresh water and would no longer float
Distinguishing feature of Schistosomes cercariae
Forked tail
What causes death in Schistosoma japonicum infection in sheep
Huge liver and spleen cause esophageal vertices to rupture
Which schistosomes cause zoonotic schistosomes dermatitis
Avian schistosomes (via contaminated water)
How are Cestoda characterized
No gut (no exceptions), Segmented, White, Live in small intestines as adults, Hermaphroditic, anterior holdfast of some sort, lay eggs that are passed in feces of final host, Final host i Infected by eating larva in intermediate host
Are segments of tapeworms older or youngest just behind the scolex
Youngest
What does each pro glottis of Cestoda usually have
Genital opening(s) Both male and female reproductive parts
Distinguish between the two types of tapeworms
Anapolyitic - segments release eggs into feces
Apolytic - segments detach and pass out with feces before releasing eggs
What are 2 types of intermediate hosts of Diphyllobothriidea tapeworms
Copepod and vertebrate
What is scientific name for broad fish tapeworm
What does it parasitize
Diphyllobothriidium latum
Fish eating mammals
Life cycle of Diphyllobothridium latum
Operculate egg in feces
Out of egg comes coracidium
Ingested by copepod and becomes procercoid
After fish ingests copepod, becomes placeroid
Eventually develops into adult
Physical characteristics of Dyphillobothrium latum
No hooks or suckers on scolex, only small groove; medial uterus
What disease is associates with Diphyllobothriidium latum
B12 deficiency in Scandinavian women
What are the important host of Spirometra mansonoides
What is associated disease called
Final host is bobcat
Can use mammalian paratenic hosts - potentially zoonotic
Sparganosis
Characterize scolex of Cyclophyllidea
4 suckers
Key points about life cycle of Cyclophyllidia
Terrestrial, only 1 intermediate host
What type if animal is the second host of Mesocestoides
Vertebrates, often dogs
Common name for Dipylidium caninum
Flea tapeworm (a Cyclophyllidia)
Where are adult DIPYLIDIUM found, how was it transmitted
How are eggs deposited
Dog and cat, ingestion of infected flea
- segments crawl out to deposit eggs
Anoplocephalids are parasites of?
Intermediate hosts are?
Herbivores, typically not pathogenic
Free living arthropods
Genus of anoplocephala in sheep and cattle
Monieza (species in cattle have square eggs)
Which anoplocephala in horse and at what site
A. Magna in jejunum
A. Perfoliats at ileo-cecal junction (has really narrow segments)
Describe final host, intermediate host, physical characteristics and geographic distribution of Thysanosoma actinoides
Sheep
Booklice
Fringed segments
Western US
Describe larval stages of Taeniid tapeworms Cystocercus Strobilocercus Coenurus Hydatid
Cyctocercus - one head per bladder
Strobilocercus - one head per bladder, but has strobilization (segments)
Coerunus - multiple heads per bladder
Hydatid - thousands of heads per cyst (only Echinococcus)
How long does it take for Taenia segment to be shed
2 months
Canine Taenia species and their larval forms
T. Ovis - cysticercus in sheep
T. Multiceps - coenurus in sheep
T. Pisiformis - cysticercus in rabbit
T. Serialis - coenurus in rabbit
T. Hydantigena - cysticercus in ruminants
Foxes: T. Crassiceps - cysticercus in rodents
What is the feline Taenia species and their intermediate host
T. Taeniaeformis
Rats (strobilicercus)
What are human Taenia species, larval type and intermediate host
Taenia sanginata - cysticercus in beef muscle
T. Asiatica - cysticercus in swine
T. Solium - cysticercus in pork and in people
Distinguish between Taenia saginata and T. solium
T. Saginata scolex has no hooks or suckers, t. Solium has sucker and 2 rows of hooks.
Pro glottis of T. Saginata has more uterine branching than t. solium
Common name for Taenia asiatica
Pork liver tapeworm
Echinococcus larval stage
Hydatid
Two important Echinicoccus species in dogs
E. granulosus
E. multilocularis
Where do Echinococcus granulosus larvae usually migrate within the cervid intermediate host to form the hydatid cyst
How do the larva get into the int. host
Lungs
Eggs released in canid feces are ingested by cervids and hatch into larva
What is a protoscolex
Larval tapeworms that develop from the hydatid cyst
Where to Echinococcus multilocularis hydatids usually develop
Lungs of rodents
