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DWT exam 2 > parasitology platyheminths > Flashcards

parasitology platyheminths Flashcards

1
Q

2 classes of platyhelminthes

A

cestoda (tapeworm)
trematoda (flukes)

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2
Q

platyhelminthes general characteristics

A

Flat mostly
Hermaphrodites
Definitive host diagnosis: eggs
At least 1 intermediate host

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3
Q

cestoda

A

phylum platyhelminthes (Flat mostly, Hermaphrodites, At least 1 intermediate host)
TAPEWORM
Segmented (can cut up and they will live), often long
Adults in host GI tract, almost always small intestine
Worms have no intestine, absorb nutrients across surface
Adults often nonpathogenic but people repelled

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4
Q

cestoda adults body divisions

A

Scolex (holdfast)
* Suckers and/or hooks NO MOUTH
* Attaches to gut wall

Neck
* Region of cell division, gives rise to proglottids

Proglottids (segments)
* Segments mature as they travel down the chain
* Oldest segments at the posterior end

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5
Q

cestoda segments

A

Each segment has at least one set of all reproductive organs of both sexes
Classified as:
* Immature
* Mature
* Gravid: contains fully developed eggs

Maturation occurs as moves down the chain
Common tapeworms shed gravid segments

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6
Q

Metacestode

A

General term for larval tapeworm
each species has its own name for this
INFECTIVE STAGE

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7
Q

cestodes general lifecycle

A
  1. eggs from adult tapeworm in definitive host passed into environment
  2. eggs eaten by intermediate host
  3. metacestode in intermediate host eaten by definitive host
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8
Q

taeniidae family

A

cestoda (platyhelmith)
Vertebrates are definitive and intermediate hosts
* Definitive host: predator mammal
* Intermediate host: herbivore or omnivore mammal—prey

Segments square to rectangular in shape
In general, larval stages (metacestode) most important, adults have little significance
Eggs passed from the host in segments
* Usually infection recognized from seeing segments
* Eggs seen infrequently in fecal exams
* Look the same for all family members
* Fecal flotation often negative because eggs in the segments

Two common/important metacestodes:
* Cysticercus
* Hydatid

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9
Q

non taeniidae families

A

cestoda (platyhelminths)
Invertebrate intermediate host, vertebrate definitive host

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10
Q

Cysticercus

A

metacestode (infective larvae) of taeniidae
Fluid-filled bladder
1 Inverted, invaginated scolex
1 Cysticercus produce 1 adult tapeworm in the DH
Infection/disease called cysticercosis

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11
Q

Hydatid

A

metacestode (infective larvae) of taeniidae
Fluid-filled bladder lines by a delicate parasitic membrane
Heads detach from wall into cyst fluid
Secondary cysts are formed as invaginations on the walls
1 hydatid produces up to thousands adult tapeworms
Infection/disease called hydatidosis

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12
Q

Taenia taeniaeformis

A

taeniidae (platyhelminths)
Common tapeworm of hunting cats
Eggs shed in segments
IH: Rodent, metacestode (Strobilocercus) in liver

CAT- MOUSE

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13
Q

Taenia pisiformis

A

taeniidae (platyhelminths)
Definitive host: canids
Egg shed in segments
IH: Rabbits

DOG- RABBIT

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14
Q

Echinococcus

A

taeniidae (platyhelminths)
Very small adults: 3-6 mm
* only 3 segments

Metacestode stage: Hydatid
Undergoes asexual reproduction
1 egg= Multiple scoleces formed
Potential for thousand of scolices to form

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15
Q

Echinococcus multilocularis

A

echinococcus, taeniidae (platyhelminths)
Life cycle
* Definitive host: Fox, sometimes dog, rarely cat
* Intermediate host: Small rodents, including lagomorphs
* Humans, dogs, and pigs: aberrant or accidental IH
* Metacestode: alveolar cyst (multilocular cyst)

Difficult to remove surgically because grows invasively

this is his fav parasite :)

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16
Q

Taenia saginata

A

5-15 m
Human/cattle
Cysticerci in bovine muscle (0.6 mm)

HUMAN-CATTLE

17
Q

T/F? Tapeworms use their suckers for feeding?

A

F

18
Q

What is the general name used for cestode larval stages?

A

metacestodes

19
Q

Where will you find metacestodes?

A

intermediate host

20
Q

Non taeniids

A

platyhelminths, cestodes
Belong to several different families (we’ll only see Dipylidiidae and Anoplocephalidae)
Use arthropod as intermediate hosts
Metacestode stage called cysticercoid: small cyst with invaginated single scolex, no fluid filled bladder

21
Q

cysticercoid

A

Metacestode stage of non taeniids
small cyst with invaginated single scolex, no fluid filled bladder

22
Q

Dipylidium caninum

A

non taeniid (cestode, platyhelminth)
15-70 cm
Most common tapeworm of dogs and cats in the US
Gravid segments released containing egg packets
Indirect life cycle, IH: fleas. Lice an uncommon IH
Flea larvae ingest egg packets, cysticercoid develop before flea become adult
Infection of DH follows ingestion of flea
PPP: 2-3 weeks
usually non pathogenic

23
Q

diagnosis of Dipylidium caninum

A

but tapeworm segments in perianal area or around feces, where animal sleeps
eggs not seen on fecals

24
Q

Dipylidium caninum - Clinical importance

A

Infection generally subclinical
Zoonotic, young children most likely to be infected, but very uncommon
Flea control critical to prevent reinfection

25
Q

Ruminant and equine tapeworm life cycle

A
  1. Gravid segments released containing eggs
  2. Eggs are ingested by the IH: Oribatid mites in pasture (coprophages)
  3. Cysticercoid in mites
  4. DH infected when ingest infected mites while grazing
26
Q

Anoplocephala perfoliata

A

equine tapeworm
Very common infection
Short tapeworm cluster at ileocecal junction
Usually asymptomatic
* Occasionally causes inflammation and ulceration
* In most severe cases associated with perforation, intussusception

Difficult to diagnose
* Surprisingly, segments not seen in manure
* Eggs usually not present on fecal exam
* Because diagnosis is difficult, horses routinely treated at least once/year
* Infection can’t practically be prevented

27
Q

Moniezia benedeni

A

cattle tapeworm
non taeniiae

28
Q

Moniezia expansa

A

small ruminant tapeworm
non taeniiae

29
Q

ruminant tapeworms

A

Moniezia benedeni (Cattle) and Moniezia expansa (Small ruminants)
Very common infection
Diagnosis
* Frequently see segments in manure, especially young animals
* Eggs in fecal exams: shape square
M. benedeni: square
M. expansa: triangular

30
Q

trematoda

A

platyhelminths
flukes

31
Q

dignena

A

trematoda (flukes), platyhelminths
Leaf shaped
Unsegmented
1-2 suckers
Operculated eggs passed in feces: usually diagnosed with fecal exam
Usually 2 IH, first IH is ALWAYS a snail

32
Q

trematode life cycle

A
  1. Most fluke eggs must hatch in water
  2. Larvae (miracidium) swim to specific snail host
  3. Some flukes use land snails, egg ingested by snail
  4. Asexual development in snail (sporocysts and redias)
  5. Next larval stage produced by snail (cercaria)
  6. Usually swims to pasture
  7. Become the infective stage (metacercaria) – sometimes in environment, sometimes in second IH
  8. Metacercaria can be ingested by a paratenic host
  9. DH is infected when ingests metacercaria

eggs > miracidium > sporocyst> redias > cercaria > metacercaria >DH

33
Q

miricidium

A

1st larval stage of trematodes
swim to snail

34
Q

Fasciola hepatica and Fascioloides magna

A

ruminant liver flukes
Adults in liver and bile ducts of host
Fasciola: ruminants, rabbits, humans, dogs, others
Fascioloides: white-tailed deer

35
Q

Fasciola hepatica - Life cycle

A

trematode, platyhelminth
1. Adults release eggs that hatch in water
2. First IH: Lymnaeid snails (asexual reproduction)
3. Cercariae encyst on vegetation and become in metacercaria
4. Ingested by DH
5. Larval fluke migrate to liver
6. After several weeks enter bile and mature

PPP: 3-4 months

36
Q

Fasciola hepatica - Clinical importance

A

In ruminants can cause chronic poor doing
May have acute disease (especially small ruminants) associated with liver migration (mechanical damage)
Diagnosis by egg detection—sedimentation technique
Control difficult because hard to eradicate snails

37
Q

Fascioloides magna

A

trematode, platyhelminth
normal host: deer
Larvae cause serious disease in sheep and goats because keep migrating around liver until animal dies
Sheep and goats are abnormal hosts
Hard to control

DWT exam 2 (22 decks)

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