iam gonna piss myself (biol368 cestodes) (so just echinococcus granulosus)

Cestodes:

  • Order Cyclophyllidea

    • Family Taeniidae: Echinococcus granulosus



PARASITE: Echinococcus granulosus

disease: cystic echinococcosis OR hydatid cyst disease OR shoemaker’s disease

geographic location: anywhere sheep are raised

host 

intermediate: sheep, herbivores

definitive: wild canids, domestic dogs

reservoir: none

transmission

route of common infection: dog will eat sheep w/ hydatid cyst

location of DEF: adults in small intestines

larval stage of INTER: metacestode in lungs and liver

life cycle of INTER: 

  1. eggs are passed in the feces and eaten by INTERMEDIATE SHEEP

  2. egg → oncosphere, which gets into gut wall and migrates to organs

  3. oncosphere → hydatid cyst

life cycle of DEF: 

  1. dog eats sheep (probably) with hydatid cyst

  2. hydatid cyst gets digested and the scolex evaginates

  3. scolex attaches to intestinal wall → strobila

  4. eggs get released into small intestine

INFECTIOUS LIFE STAGE (DEF): hydatid cyst

INFECTIOUS LIFE STAGE (INTER/ACC): metacestoda, hydatid cyst

DIAGNOSTIC LIFE STAGE: taenia eggs in feces

pathogenesis: 

how does the parasite cause disease:

symptoms: in intermediate (sheep) only. poor growth, pneumonia, liver disease

in humans, cysts will grow slowly and there will be necrosis from large cysts → anaphylactic shock will occur when the cyst ruptures, which can cause infection in other tissues. will not cause disease in definitive host!

diagnostic tests: 

target? (lifestage/antibody/genetic material): taenia eggs in feces, necropsy will find them bitches, CT scans/MRI/ultrasound, serology for blood

prevention methods: deworm sheep dogs, DON’T EAT RAW SHEEP!!!!, pick up dog feces, wash hands after touching dogs, wash/cook food

control methods: none

treatment methods: praziquantel for definitive only. humans require surgery for large cysts + benzimidazol drugs for small cysts