Parasitology 10: Protozoa Flashcards
If you house sheep in a space where you previously had, poultry, remained poultry coccidia can infect the sheep? t/f
False
coccidia is VERY specific
Eimeria/Cystoisospora oocysts are infective immediately after shed in feces
What is patent infection in Eimeria/Cystoisospora?
Is when the whole lifecycle is complete and the oocyst were developed
What life cycle do Eimeria and Cystoisospora?
DIRECT
What is Bradyzoite and Tachyzoite?
Bradyzoite : zoite of Apicomplexa with slow multiplication in cysts
**Tachyzoite* : zoite of Apicomplexa undergoing quick asexual multiplication in a host cell
Toxoplasma gondii
important?
coccidian species with what as DH?
life cycles direct and indirect but what are the new 2?
IMPORTANT zoonotic parasite
coccidian species with CAT as DH
- Bradyzoite
- Tachyzoite
Toxoplasma life cycle
Felids are only DH- sexual stages only in cats
3 infectious stages
Tachyzoites (groups or clones)
Bradyzoites (tissue cysts)
Sporozoites (sporulated oocysts)
IH= other warm blooded animals
When other warm blood animal eats sporulated oocysts:
- sporozites emerge
-penetrate intestine
-undergo rapid multiplication in cell: tachyzoites , which spread to all other tissues
-Eventually conversion occurs to cysts containing bradyzoites (infective stage as well)
What is important to remember about Tachyzoite and Bradyzoite?
t= rapidly multiplying tissue stage, pathogenic stage
b= slowly dividing stage in cysts
-these stages are found in all animals infected with toxoplasma, including felids
-Only felids have the sexual stages in the intestine
Can cats be IH when talking about toxoplasma gondii?
YES
A cyst in toxoplasma gondii life cycle are?
ALL bradyzoites
Which life cycle does toxoplasma gondii have?
Direct AND Indirect
prefers indirect
Cat infections of toxoplasma gondii works how?
*Ingesting bradyzoites in cysts
* Most common and efficient route
* Get intestinal stages with multiplication and
gametogony
* Also leads to tachyzoites and bradyzoites (tissue cysts)
Ingesting sporulated oocysts or tachyzoites
* Less efficient, may not lead to patent infection
* Tissue multiplication with tachyzoites and bradyzoites
* Some may go back to GI and complete cycle
Non-felid infections toxoplasma gondii works in what way?
Several ways
* Ingesting oocysts (sporozoites)
* Ingesting bradyzoites in cysts
* Congenitally
* Rare tachyzoite transmission
Result of all these routes: tachyzoite multipication and then bradyzoites in cysts
Toxoplasma gondii in Cats
prevalence
most infections
disease
- High prevalence of antibodies in cats, 50% or more
- Most infections in cats probably occur in young
cats
-Immunity develops, prevents recurrence of oocyst
shedding - Only about 1% oocyst prevalence in feline fecal
samples
-Cats shed oocysts for just a few weeks, reshedding
unlikely - Disease in cats is rare
-Disease caused by tissue tachyzoites
Toxoplasma gondii in other animals
abortion and species
Common cause of abortion in small ruminants
* Occurs when first infection takes place during pregnancy
* Immunity develops and protects subsequent pregnancies
Cattle less susceptible to infection, abortion not seen
Sporadic disease in some circumstances
* Exotic animals in zoos, otters, marine mammals, birds, animals that are immunosuppressed
What is the public health importance of toxoplasma gondii?
Humans can become infected by any of several routes
-undercooked meat (cyst)
-contaminated water and food
-transfusion
-transplacental
You can see the parasite systemically in humans
The biggest problem is ocular problems (blindness) irreversible
Neospora canium is what?
Similar to toxoplasma but in dogs
Dogs and wild canids are the DH
Not zoonotic
Causes abortion in cattles
What species is Neospora canium affect badly?
Cattle
can cause abortion, or lead to persistant infection than can infect subsequent pregnancies and may lead to abotion
-calves can be born and live with persistent infection and later abort
Persistently infected cows have a higher abortion rate than non-infected cows
Sarcocystis spp
life cycle
species
cyst name in IH called
*Obligate indirect life cycle
*Many species, often host specific for
both intermediate and definitive host
*Cyst in intermediate host called a
sarcocyst
Sarcocystis spp
Sarcocystis neurona is important why?
Primary cause of Equine protzoal myeloencephalitis
horse is a dead-end host
What is the life cycle of sarcocystis neurona?
What are the clinical signs of Sarcocystis neurona?
-Many horses serologically positive
-Most infections asymptomatic
In some horses parasites in the CNS produce disease
* Lameness
* Stumbling
* Muscle atrophy
* Paresis
Definitive diagnosis and treatment are difficult
Neospora hughesi can also cause EPM, but S.
neurona more common
Summary of species of parasite and its host?
