Platyhelminths Flashcards
Platyhelminth
Flat worm
Tegument is spines or smooth, body compressed and flat
Digestive system is a blind sac
Hermaphroditic usually
Monogenea
Small parasitic fluke on fish, amphibians and turtles
No/ weak oral sucker
Use large posterior organs for attachment
No intermediate hosts- aquaculture
Trematodes
All parasitic, endoparasites
Digenea, trematodes
Sexual or asexual
2+ hosts and the first is always a snail
2 attachment organs, ceca for digestion and hermaphroditic
Flukes
Suck blood
Obstruct ducts and vessels
Egg accumulation
Destroy tissues/ organs via feeding, migration and pressure necrosis
Life cycle of flukes
Snail - microcidium- sporocyst- rediae or cercariae
Cercariae leaves snail into environment before becoming metacercaria
Sporocyst
Develops in snail and produces radiae or cercariae
Rediae
Can be omitted
Cercariae
- Penetrate/ingested by 2nd IH
- Attach to vegetation
- Penetrate DH directly
Ways to get to metacercaria
Metacercaria
Encyst in environment or transport host
Infects DH and infective stage
Schistosomes
Tubular body
Dioecious
No 2nd IH, only 1
Mature in the blood of the DH
Many species pathogenic in humans, cercariae in water to skin
Trematode Dx
Sedimentation
Cestoda
All parasitic, adults in SI
Muscular and nervous systems
Scolex- attachment organs and proglottids have repro organs
Hermaphroditic
Gravid proglottids
Eggs within
Largest size
Dipylidium caninum
Rounded proglottids
Spirometra mansonoides
Wide proglottids
Taeniid tapeworm
Very long and thin
Cyclophyllideans
True tapeworms
Scolex can be armed or unarmed, hooks, also have 4 suckers
1 to 2 proglottids and no uterine pore, only genital pore
Hexacanth eggs
Metacestode type is species dependent
Cysticercoid
Single, not invaginated scolex
Invertebrate IH
Cysticercus
Single invaginated scolex
Vertebrate IH
Coenurus
Many invaginated scolices, vertebrate IH
Goal of metacestodes, larvae of cyclophyllideans
Eaten by DH, want IH to die
Strobilocercus
Single, non invaginated scolex attached to bladder
Hydatid cyst
Brood capsules with 100s of protoscolices
Larvae form for metacestodes
Pseudophyllideans
False, scolex is a bothria
1 set of proglottids, and have genital and uterine ores
Eggs are operculated and coracidum
Larvae are metacestodes
Pseudophyllidean metacestodes
Procercoid is in the 1st IH and plerocercoid is in the 2nd IH
1st is typically a copecod and 2nd is a fish or frog
Plerocercoid can get very long, sparganum
Cestode dx
Fecal float
Pay attention to specific gravity
