Zoonotic parasites Flashcards
Compare and contrast the diseases of Toxoplasmosis and Toxascariasis.
Toxoplas: due to Toxoplasma gondii (protozoan). Definitive host: cats
Toxoscar: due to larvae of nematodes (roundworm). Definitive host: cats & dogs
Compare: humans accidental host
Provide advice on how zoonotic parasitic disease may be avoided.
- pick up poo promptly & discard
- wash hands frequently after touching animals
- avoid contact to animal faeces
Angiostrongylus cantonensis
a) pathogenic effects
b) clinical signs & symptoms
a) eosinophilic meningitis
b) eosinophilic meningitis, ocular angiostrongyliasis
Echinococcus granulosa
a) pathogenic effects
b) clinical signs & symptoms
a) Forms cyst in host in inner germinal layer => granluomatous rxn
b) Abdominal pain, mass in hepatic area, bile duct obstruction, eosinophilia
Define:
a) paratenic host
b) incidental (‘dead-end’) host
a) similar to an intermediate host, but not needed for the parasite’s development cycle e.g. vector
b) intermediate accidental host preventing parasite to complete development & transmission to definitive host
lifecycle of Angiostrongylus cantonensis
- Eggs hatch in rat’s lung
- larvae coughed up & swallowed => faeces
- L1 infect snails, slugs =>L2, L3
- L3 (infective stage) ingested by rats
For Angiostrongylus cantonensis name the:
a) diagnostic form
b) infective form
c) if applicable, name the type of intermediate host
a)
b) L3 in snails/slugs
c) snail/slugs
Dx methods for Angiostrongylus cantonensis
- Eosinophilia in peripheral blood
- Cerebrospinal fluid
- serological test available
common manifestation for zoonotic infection w/ animal hookworm sp
cutaneous larva margins (aka ground itch)
- cause intense pruritic track in upper dermis
Lifecycle of Toxocara canis (in dogs)
- unembryonated egg shed in faeces of dog
- Eggs embryonate (infective) in evironment
- eggs ingested by other dogs
- hatch & larvae penetrate through gut wall
- In puppies, the larvae migrate to lungs to develop
- In adult dogs, the larvae develop in S.Intestine
For Toxocara canis name the:
a) diagnostic form
b) infective form
c) if applicable, name the type of intermediate host
a) unemryonated egg in dog poo
b) embryonated egg in environment
c) can be Rabbits -> ingested by dog (eat cyst)
clinical presentations/dx of toxocariasis in humans (accidental host) (2)
- visceral larva margin (VLM): invade multiple tiss/organs often in children
- ocular larva margins (OLM): opthalamologic lesion in one eye => permanent vison loss in older children or Y.Adults (misdx as retinoblastoma)
dx test for toxocariasis
serological test: enzyme immunoassay (EIA)
lifecycle of toxoplasmosis (& form in humans)
- unsporulated oocyst in cat’s poo
- Intermediate host (mice, bird) eat oocyst-contaminated food/water
- Oocytes transform into tachyzoites -> muscle tiss = cyst bradyzoites (infective)
- cats eat intermediate host w/ cyst
* tissue cyst in humans
For Toxoplacmosis name the:
a) diagnostic form
b) infective form
c) if applicable, name the type of intermediate host
a) isolate parasite in body fluid or blood from mice
b) cyst in muscle of intermediate host
c) mice or bird
