Parasitic Protozoa - Apicomplexa, 2 (40) Flashcards
What is neospora caninum?
a coccidial parasite of dogs
Who are the DH for neospora caninum? They are the only hosts ______
dogs - domestic and wild
only host with sexual multiplication
oocysts in small intestine epithelium
Neospora caninum is morphologically similar to _____. How do you differentiate between the two?
toxoplasma gondii
caninum: oocysts ~10um and generally fewer
Regarding neospora caninum, ____ and _____ are in tissues of the IH and DH
tachyzoites
bradyzoites
How is neospora caninum immunologically, biologically, and epidemiologically different than toxoplasma gondii?
biologically: predominately indirect lifecycle
> ingestion of tissue cysts in IH
epidemiologically: NOT zoonotic
» significant in cattle production
Who are the only competent IHs for neospora caninum? What happens?
domestic livestock, grazing wildlife, and dogs
viable parasites capable of in vivo passage
infected by oocysts
vertical transmission
A dog was experiencing neuromuscular disease and had a history of eating carcasses. Fecal flotation revealed these 10 um oocysts. How was the host infected?
ingestion of oocysts
tachyzoites and bradyzoites in tissues
(this parasite is neospora caninum)
What is the clinical significance of neospora caninum?
neuromuscular disease in canines
congenital infection - asymptomatic at birth
What types of dogs have more serologic prevalence with neospora caninum?
farm dogs: 51%
exposure to cattle - fetuses, placenta
What is the clinical significance of neospora caninum in cattle?
reproductive disease
history of abortion 2x likely to be seropositive
disease of the placenta/fetus
A calf infected with neospora caninum likely has symptoms of _____
neuromuscular disease
dam has primary infection
Regarding neospora caninum, [dairy/beef] cattle are 3x more likely to be seropositive
dairy
What is the economic impact of neospora caninum?
primarily reproduction
production losses
epidemic “abortion storms”
A tissue cyst (left) was identified in a fetal cow brain. Tachyzoites in cattle tissue are shown on the right. What is the parasite that affected them?
neospora caninum
How do you treat neospora caninum in dogs?
no FDA approved or curative treatment
clindamycin
trimethoprim sulfadiazine
How do you prevent neospora caninum in dogs?
do not allow access to fetal or placental tissues
do not feed raw meat
do not breed females previously diagnosed with clinical disease or whelped litters with affected puppies
avoid immunosuppressive therapies in seropositive dogs
How do you treat cattle infected with neospora caninum?
no FDA approved treatment
toltrazuril/ponazuril - helps infected calves
vaccine - x withdrawn from market
How do you prevent neospora caninum outbreaks in herds?
T/F: Neospora caninum has a lifetime risk of congenital infection
TRUE - toxoplasma gondii does NOT
Compare and contrast toxoplasma and neospora
How are IHs infected with sarcocystis? What are the specific IHs?
ingestion of tissue cysts in specific intermediate hosts
sheep-dog
cow-dog
etc
Regarding sacrocystis sp., who are the only hosts where sexual replication occurs?
dogs, cats (domestic & wild)
For sarcocystis sp, sexual reproduction occurs in the ______. There are sporocysts with ____ sporozoites on fecal flotation
small intestine
4
How does sarcocystis replicate in the IH? Where in the IH?
asexual replication in striated muscle or endothelial cells
production losses may be associated
equines accidental host for s. neurona (EPM)
domestic livestock, birds, grazing wildlife
What is the parasite? How do you know?
sarcocystis sp.
~15 x 8 um, with 4 sporozoites
How do humans obtain sarcocystosis?
human eats undercooked meat containing mature sarcocysts
human is a DH
What is the lifecycle of sarcocystis cruzi? DH? IH?
obligate indirect lifecycle
DH: dogs
IH: cattle
Trace the lifecycle of sarcocystis cruzi
dog ingests tissue cysts in cattle, sporocysts in feces ~2 weeks post-infection
cattle infected by sporocysts while grazing
- 2 generations of asexual replication
- development of inductive stage “sarcocysts” in striated muscle fibers
What is the clinical significance of sarcocystis cruzi?
most infections are asymptomatic
- no clinical disease in dogs (DH)
sporocysts shed in feces
adverse health effects in cattle (IH)
Describe the adverse health effects in cattle (IH) regarding sarcocystis cruzi
abortion, still birth, eosinophilic myositis
necrotic encephalitis in two heifers
fever, anorexia, diarrhea, muscle spasm, loss of tail hair, hyperexcitability
cachexia, weakness, decreased milk yield (cows)
Calves that survive acute infection of sarcocystis cruzi _____
fail to thrive
premature death in cachectic state
How do you treat sarcocystis cruzi infection in cattle?
treatment of infected hoof stock not economically practical
- amprolium
How do you prevent sarcocystis cruzi infection in cattle and dogs?
exclude dogs from production facilities
keep ration covered to prevent fecal contamination
periodic fecal examination of dogs to monitor sporocyst shedding
Who are the DHs and IHs for sarcocystis neurona?
DH: opossum - sporocysts in feces
IH: select mammalian - isolate tissue cysts for in vivo passage to other hosts
_____ are aberrant/accidental hosts of sarcocystis neurona
Horses - dead end host
tissue cysts are not viable and do not produce infection in DH
How do horses get sarcocystis neurona?
infection by ingestion of sporocysts in contaminated feed/pasture
A horse is experiencing neurologic disease like ataxia and incoordination. Diagnosis by serology indicates IgG antibodies. What is the etiologic agent and disease? How did she get this?
sarcocystis neurona
Equine Protozoa Myloencephalitis
infection by ingestion of sporocysts in contaminated feed/pasture
How do you diagnose sarcocystis neurona in horses?
serology
IgG antibodies
IFA testing to distinguish EPM caused by s. neurona or n. hughesi
EPM is rare
What is EPM distribution?
endemic to North and South America
T/F: Equine Protozoa Myeloencephalitis is common due to the seroprevalence in 30-50% of tested horses
FALSE - is sporadic! (seroprevalence is true though)
_______ of sarcocystis neurona is associated with disease potential and response to treatment
Serologic phenotypes
What are the serologic phenotypes of sarcocystis neurona and the neurovirulence percentages?
SAG 1 - 93%
SAG 5 - 7%
SAG 6
How do you treat sarcocystis infection?
prophylactic drug use - questionable and expensive
ponazuril, FDA approved
sulfadiazine/pyrimethamine - interfere with parasitic synthesis of folic acid and inhibit energy metabolism, need folic acid supplements
T/F: Sarcocystis neurona infection is a “condition” of antibody prevalence more than a “neurologic disease” of horses (EPM)
TRUE - more horses have antibodies than express neurologic disease
clinical disease expression may be a function of SAG rather than simple infection with the parasite
