- single scolex NOT invaginated - usually seen in invertebrate IH like fleas or mites - this is a TYPE of metacestode

single invaginated scolex usually vertebrate IH - inside out, small fluid-filled bladder - a TYPE of metacestode

Cestodes Flashcards by Melissa Feldman

cestodes: general characteristics

all are parasitic: adults in sm. intestine of vertebrates, larvae in invertebrates or vertebrates
no digestive, circulatory, respiratory or skeletal systems
muscular system & nervous system
body of scolex (mouth) & proglottids (body segment)
hermaphroditic

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cestodes - taxonomy

cestodes aka tapeworms are a class of platyhelminthes aka flatworms

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proglottid types

immature proglottids - anterior end
mature proglottid - middle of body
gravid proglottid - toward posterior, full of eggs,

species specific in both IH and DH

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two orders within cestodes

cyclophyllideans = true tapeworms

2. pseudophyllidea = pseudotapeworms

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general characterisitcs of cyclophyllideans (true tapeworms)

has a scolex of 4 different suckers (can be armed or unarmed)
proglottids (NO uterine pore)
each egg can form one tapeworm
IH must ingest eggs
metacestode - larvae DH must ingest

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cysticercoid

single scolex NOT invaginated
usually seen in invertebrate IH like fleas or mites
this is a TYPE of metacestode

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cysticercus

single invaginated scolex usually vertebrate IH

inside out, small fluid-filled bladder
a TYPE of metacestode

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coenurus

a large fluid-filled bladder containing multipe invaginated soclices in vertebrate IH

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goal of the cyclophillidean

KILL the IH because it cannot complete its life cycle until its eaten by the DH

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unilocular hydatid cyst

broad capsules with 100s - 1000s of protoscolices, very large, thick-walled filled with fluid

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multilocular hydatid cyst

not contained by the thick-walled compartment

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characteristics of Pseudophyllideans

scolex: bothria = 2 slit-like structures (no hooks or suckers)
proglottids - 1 set of repro organs, central genital pore
- uterine pore in center
- eggs are operculated and WILL float in fecals!
- larvae have a metacestode in IH

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diagnosis of cestodes (tapeworms)

fecal floatation

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simple vs. centrifugal fecal flotation

flotation is how you find most nematod eggs, larva and tapeworm eggs.

need at least 1 gm
use correct soln
for simple, it must SIT for 15-20min

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Dipylidium caninum : taxonomy

part of order cyclophyllidean class cestodes phylum platyhelminthes

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dipylidium caninum: general characterisitics

aka cucumber seed tapeworm
- SI of dogs, cats, children
- found worldwide
- indirect lifecycle
- IH: fleas, dog louse
- metacestod: cysticercoid
- adults repro system has: 2 sets of proglottids, NO uterine pores.
adults scolex has 4 suckers, armed with rostellum & hooks
- eggs: found in packets, hexacanth embryo

life cycle of dipylidium caninum

adults in SI of cat or dog. gravid proglottids break away from the chain and are passed in feces
proglottids rupture - egg packets released as well as individual eggs
eggs are ingested by IH - larval fleas or louse
hexacanth embryo matures to cysticercoid once adult flea is on DH needs 30 - 32C
reaches infective cysticercoid within 36 hours after flea is on DH
flea is ingested by DH - cysticercoid digested out, releases, scolex, attaches to SI - begins to grow.
- prepatent period = 2-3 weeks

dipylidium caninum : pathogenicity

usually not pathogenic
heavier infections cause: constipation, diarrhea, pot-bellied appearance
migrating proglottids may make host itch
steals nutrition from DH

control of dipylidium caninum

control fleas &/or lice

Anoplocephala spp. taxonomy

species of order cyclophyllidean, class cestode, phylum platyhelminthes

Anoplacephala perfoliata

“lappeted tapeworm”

congregates near ileocecal valve
has lappets behind each sucker <– diagnostic feature

anoplocephala magna

“large scolex tapeworm”

no lappets
SI, especially jejunum
large scolex which does NOT have hooks

paranoplacephala mamilana

“dwarf tapeworm”

SI
narrow scolex
NO lappets
has 4 suckers

life cycle of anoplacephala spp.

DH is horse
prepatent period = 6-16 weeks
eggs short-lived, must be ingested quickly
egg hatches and cysticercoid develops over 8-20 weeks
infection accidental during grazing

pathogenicity of anoplacephala spp.

anoplacephala perfoliata: attaches to GI mucosa, causes ulcerative lesions and mucosal degeneration, possible risk factor for impaction colic, chronic symptoms: ill thrift, recurring diarrhea, weight loss anoplocephala magna & paranoplacephala mamilana: rarely disease, large numbers may cause hemorhagic enteritis

diagnosis of anoplacephala spp.

- fecal flotations - look for proglottids - following to find species: - indirect ELISA - serologic ELISA - necropsy

Taeniids: taxonomy

order cyclophllidean, class cestode, phlyum platyhelminthes

taeniids: general characterisitcs

- large worms - proglottids longer than wide - ARMED (row of hooks) - single genital pore - all eggs look exactly alike, 6 exocant hook embryo inside egg - humans can be IH host - all have metacestode stages (in IH) - all dx via fecal flotation

life cycle of general taeniid

1. adult tapeworms attach to SI of DH. gravid proglottids passed in feces, rupture, eggs released 2. IH ingests eggs - hatch in intestine. oncosphere (hexacanth embryo) released, penetrates intestinal mucosa, enters circulation 3. metacestode stage develops in various organs or tissues 4. DH infected by ingestion of raw, undercooked meat. metacestode releases scolex which attach to SI - grows to adults

taneia pisformis (csticercus pisiformis)

"abodminal tapeworm" "abdominal bladderworm" "rabbit tapeworm" adult: SI of dogs, 200cm metacestode: peritoneal cavity of rabbits & hares, frequently attach to serosal surfaces of abdominal organs

spirometra mansonoides

order pseudophyllidean, class cestode, phylum platyhelminthes

spirometra mansonoides: general characteristics

hosts: felids and canids - common tapeworm of cats in Fl - they are everywhere here zoonotic! humans will get larval stages but not the adult - uterus is in the center, very dark spot straight down middle making it easy to ID - distribution: mainly southeastern US - repro system: one set/proglottid --> uterine pore - scolex with 2 bothria - eggs: operculate - metacestode stages: procercoid (1st IH usually copepod), plerocercoid (2nd IH, usually frog, rat, snake)

life cycle of spirometra mansonoides

1. adults in SI of the cat or dog. eggs are passed in feces via uterine pore 2. a coracidium develops in egg and emerges upon contact with water 3. 1st IH - copepod ingests coracidium - develops into procercoid 4. 2nd IH - frog, rat, snake, ingests copepod - procercoid develops into plerocercoid 5. plerocercoid encysts in muscles of 2nd IH 6. 2nd IH/plerocercoid ingested by DH - digested out of muscle, attaches to SI - grows and matures

pathogenicity of spirometra mansonoides

- most cases asymptomatic may have vomiting, diarrhea, weight loss - zoonosis either by ingestion of copepod (ie frog legs) or via 2nd IH by applying cold meat as compress to an open wound

diagnosis of spirometra mansonoides

one of the hardest tapeworms to treat | - fecal examination: should look bubbly

control of spirometra mansonoides

- preventing predation of 2nd IH by dogs and cats | - avoid ingesting undercooked meat