Cysticercosis
/ Hydatid Disease
Epidemiology and Etiology:
- Taenia solium – cysticercosis
- Echinococcus
granulosus – hydatid
disease
- Foods infected:
- T. solium:
- Undercooked pork
containing larval cysts
- Water containing
human / pork feces
- E. granulosus /
E. multilocularis:
- Water containing
dog feces / fox feces (eggs)
- Life cycle:
- T. solium:
- Ingestion of larvae
(undercooked pork)
- Attach to the
intestinal wall
- Develop into
mature adult tapeworms
- Eggs laid pass
into feces
- Eggs ingested by
intermediate host (pig, human)
- Larvae hatch and
penetrate the gut wall
- Disseminate hematogenously
- Encyst in many
organs
- E. granulosus /
E. multilocularis:
- Humans are
intermediate hosts only
- Ingestion of eggs
(water containing dog feces)
- Larvae hatch and
penetrate gut wall
- Invade liver,
lungs, bones
Common sites:
- Cysticerci:
- brain
- muscles
- skin
- heart
- liver (2/3 of E.
granulosus cysts)
- lung
- bones
Gross features:
- E. granulosus cysts tend to be unilocular
- E.
multilocularis cysts
tend to be multilocular
- Ovoid cysts
Histologic features:
- Cysticerci may
be found in any organ
- ovoid cysts:
- begin small
(microscopic)
- thick wall
(>100um)
- inner, nucleated,
germinative layer
- outer,
non-nucleated laminated layer
- surrounding
fibrous capsule over time
- contain
invaginated scolex with hooklets, bathed in clear fluid
- little host
reaction when intact
- when degenerated,
inflammatory reaction composed of mononuclear leukocytes and eosinophils
- larvae in organs:
- lodge within the capillaries
- inflammatory
reaction composed of mononuclear leukocytes and eosinophils
Immunophenotype:
Marker:
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Sensitivity:
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Specificity:
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Molecular features:
Other features:
- T. solium
cysts evade host immune defenses:
- taeniaestatin –
serine proteinase inhibitor that inhibits complement activation
- paramyosin –
inhibits the classical pathway of complement activation
References: