Pseudophyllidea, Cyclophyllidea, and Taeniidae Flashcards
What are some defining characteristics of tapeworms?
They have an indirect life cycle, adults are in the small intestine, the DH is infected by eating the IH with the larva called “metacestode”
Anatomy of a true tapeworm
Head=scolex, body=strobila with repeating segments called proglottids, scolex has four muscular suckers and a rostellum. Egg has a first stage larva called hexacanth embryo that is infective for host
Anatomy of a false tapeworm
Bothria, no mouth or alimentary canal. Egg passed from uterine pore, operclated eggs with coracidium only viable if in water
What is important about proglottids?
Each one has a male and female repro system, produce many eggs, may self fertilize, absorption of nutrients through wall. Gravid ones break off and release eggs
Dipylidium caninum
Most common, 2 genital pores, fresh proglottids look like cucumber seeds. Egg packets eaten by flea larvae and become a cysticercoid as flea develops. DH infected when it eats fleas. PPP is 2-3 weeks.
Treatment for D. caninum?
Praziquantel, recurrence is common because fleas are and because it has a short PPP. Rarely zoonotic
Taeniidae metacestodes
Cysticercus for all Taenia spp with invaginated scolex and bladder, or Coenurus for Taenia spp. (single bladder with many scolices), Strobilocercus for Taenia taeniaeformis that elongates and segments while in IH, hydatid cyst for Echinococcus spp. (fluid filled, hundreds or thousands of scolices). PPP is 2-3 months
What is special about the diagnostic stage egg?
There is only a taenia type egg-cannot differentiate between Taenia spp and Echinococcus spp. Remember worm is rectangular.
Treatment for Taenia?
Praziquantel, regular treatment, don’t let them eat carcasses
Two most common tapeworms for dogs and cats?
Dipylidium caninum for both, Taenia pisiformis for dogs and Taenia taeniformis for cats
Echinococcus granulosus
very small, causes hydatid disease (zoonotic). Unilocular hydatid cyst develops. Canines ingest cyst in IH.
Echinococcus multiocularis
Alveolar Hydatid Disease (zoonotic), mice and voles are the IH, highly invasive and may undergo budding
Is AHD zoonotic?
YES. Humans can be IH and the highly invasive cyst stage leads to AHD. Mortaity is about 60%. Serologic tests confirm. Surgery is best option but is difficult to remove, have to be on drugs for life.
Is Hydatid Disease zoonotic?
YES. Humans can be IH by ingesting eggs, leading to slowly developing cysts in major organs.
Mesocestoides spp.
scolex with 4 suckers, no rostellum or hooks. Parauterine organ, huuuuge worm. Life cycle needs 2 IH. 1st is mite or dung beetle with cysticercoid metacestode. 2nd is reptile, amphibians, mammals with tetrathyridium metacestode. Dogs/cats can be 2nd IH or DH. Can cause Peritoneal Larval Cestodiasis which is life threatening to dogs.
