Cestodes

Question 0

cestodes: general characteristics

Answer 0

• 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

Question 1

cestodes - taxonomy

Answer 1

cestodes aka tapeworms are a class of platyhelminthes aka flatworms

Question 2

proglottid types

Answer 2

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

species specific in both IH and DH

Question 3

two orders within cestodes

Answer 3

1. cyclophyllideans = true tapeworms

2. pseudophyllidea = pseudotapeworms

Question 4

general characterisitcs of cyclophyllideans (true tapeworms)

Answer 4

• 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

Question 5

cysticercoid

Answer 5

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

Question 6

cysticercus

Answer 6

single invaginated scolex usually vertebrate IH

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

Question 7

coenurus

Answer 7

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

Question 8

goal of the cyclophillidean

Answer 8

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

Question 9

unilocular hydatid cyst

Answer 9

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

Question 10

multilocular hydatid cyst

Answer 10

not contained by the thick-walled compartment

Question 11

characteristics of Pseudophyllideans

Answer 11

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

Question 12

diagnosis of cestodes (tapeworms)

Answer 12

fecal floatation

Question 13

simple vs. centrifugal fecal flotation

Answer 13

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

Question 14

Dipylidium caninum : taxonomy

Answer 14

part of order cyclophyllidean class cestodes phylum platyhelminthes

Question 15

dipylidium caninum: general characterisitics

Answer 15

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

Question 16

life cycle of dipylidium caninum

Answer 16

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

Question 17

dipylidium caninum : pathogenicity

Answer 17

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

Question 18

control of dipylidium caninum

Answer 18

control fleas &/or lice

Question 19

Anoplocephala spp. taxonomy

Answer 19

species of order cyclophyllidean, class cestode, phylum platyhelminthes

Question 20

Anoplacephala perfoliata

Answer 20

“lappeted tapeworm”

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

Question 21

anoplocephala magna

Answer 21

“large scolex tapeworm”

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

Question 22

paranoplacephala mamilana

Answer 22

“dwarf tapeworm”

• SI
• narrow scolex
• NO lappets
• has 4 suckers

Question 23

life cycle of anoplacephala spp.

Answer 23

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

Question 24

pathogenicity of anoplacephala spp.

Answer 24

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

Question 25

diagnosis of anoplacephala spp.

Answer 25

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

Question 26

Taeniids: taxonomy

Answer 26

order cyclophllidean, class cestode, phlyum platyhelminthes

Question 27

taeniids: general characterisitcs

Answer 27

- 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

Question 28

life cycle of general taeniid

Answer 28

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

Question 29

taneia pisformis (csticercus pisiformis)

Answer 29

"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

Question 30

spirometra mansonoides

Answer 30

order pseudophyllidean, class cestode, phylum platyhelminthes

Question 31

spirometra mansonoides: general characteristics

Answer 31

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)

Question 32

life cycle of spirometra mansonoides

Answer 32

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

Question 33

pathogenicity of spirometra mansonoides

Answer 33

- 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

Question 34

diagnosis of spirometra mansonoides

Answer 34

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

Question 35

control of spirometra mansonoides

Answer 35

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