Parasitology 8: Platyhelminthes 2 Flashcards
Tapeworm use their suckers for feeding?
FALSE
no suckers
What’s the general name used for the cestode larval stages?
Metestode
Where will you find the metacestodes?
Intermediate
The metacestode of Echinococcus is cysticerus
False
The IH of Taenia pisiform
Rabbit and Dog
Non-taeniid common tapewroms what are we focusing on?
Dipylidiidae
Anoplocephalidae
-arthropod as intermediate host
-Metacestode stage called cysticercoid: small cyst with invaginated single scolex, no fluid filled bladder
Dipylidium caninum
where?
size?
common?
- Parasite of dogs and cats worldwide
- 15-70 cm
- Most common tapeworm of dogs and cats in the US
Dipylidium canium- Life cycle
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
How do yo diagnosis Dipylidium caninum?
Tape worm segments in perianal area or around feces, where animal sleep
Egg packets usually NOT seen in fecal exams UNLESS segment broken up in sample (like taenia spp.)
Egg packet around 200um. BIGGER
do NOT confused with hook worms eggs that are smaller 60-80um
Do dogs like the taste of dipylidium canium eggs/larvae?
Yes!
What is the Clinical importance of Dipylidium canium?
Infection generally subclinical
ZOONOTIC, young children most likely to be infected, but very uncommon
Flea control CRITICAL to prevent reinfection
What are the common ruminant and equine tapeworms
A. perfoliata
MOST IMPORTANT IN HORSE
-short
Ruminant and equine tapeworms
Life cycle?
Gravid segments released containing eggs
eggs are ingested by the IH: orbatid mites in pasture (coprophages)
Cysticercoid in mites
DH infected when ingest infected mites while grazing
Anoplocephala perfoliata affect what species?
how does it work
HORSES
IMPORATNT becasue of location
-VERY common
-short at ileocecal junction
-Asymptomatic
-occasionally causes inflammation & ulceration
-MOST several cases associated with perforation, intussusception
Clinical importance of Anoplocephala?
*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
Trematoda - flukes
shaped?
segmentation?
suckers?
eggs?
what intermediate host? ALWAYS
Leaf shaped
unsegmented
1-2 suckers
Operculated (lid like of egg) eggs passed in feces: usually diagnosed with fecal exam
Usually 2 IH–1st is ALWAYS SNAIL
What is the life cycle of Trematode?
*Most fluke eggs must hatch in water
Larvae (miracidium*) swim to specific snail host
*Some flukes use land snails, egg ingested by snail
Asexual development in SNAIL (sporocysts* and redias)
- Next larval stage produced by snail (cercaria)
- Usually swims to pasture
- Become the infective stage (metacercaria) – sometimes in
environment, sometimes in second IH - Metacercaria can be ingested by a paratenic host
- DH is infected when ingests metacercaria
What it the life cycle of Fasciola hepatica?
Adults release eggs that hatch in water
First IH: Lymnaeid snails (asexual reproduction)
Cercariae encyst on vegetation and become in
metacercaria
Ingested by DH
After ingestion by DH
- Larval fluke migrate to liver
- After several weeks enter bile and mature
PPP: 3-4 months
What are other fluke-transmitted disease?
Fluke of bats (Acanthatrium
oregonense*) and
insectivorous birds serves as
vector of Ehrlichia risticii
(Potomac Horse Fever)
*Horses just innocent bystanders in cycle
