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Parasitology > Apicomplex pt 2 > Flashcards

Apicomplex pt 2 Flashcards

1
Q

There is only one specie of toxoplasma within the genus (gondii), but there are many ________

A

Genotypes

- vary in virulence, transmission efficiencies, etc

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2
Q

Toxoplasma gondii is distributed _____

A

Worldwide

- seen on every continent

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3
Q

T. gondii definitive host

A

Felidae

- domestic and wild

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4
Q

Does T gondii have intermediate hosts?

A

Yes

  • all warm-blooded animals (mammals and birds)
  • serve as source of infection
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5
Q

Less common routes of transmission for T gondii

A
  • blood transfusion: circulating stages of tachyzoites in blood
  • organ transplant: could have tissue cysts present
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6
Q

Cats are infected with T gondii by getting exposed to ____

A

Sporulated oocysts

- typically get ingested by grazing animals exposed to soil

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7
Q

T gondii tissue cysts

A

Seen in intermediate hosts

  • asexually reproducing
  • only when cyst opens or gets compromised will you see disease
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8
Q

_______ transmission can happen in intermediate or definitive hosts

A

Transplacental

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9
Q

What 2 apicomplexa sporulate inside the host?

A
  • sarcocystis

- cryptosporidium

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10
Q

What 5 apicomplexa sporulate outside the host?

A
  • toxoplasma gondii
  • hammondia
  • isospora
  • eimeria
  • neospora
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11
Q

Toxoplasma gondii routes of infection

A
  • ingestion of tissue cysts in IH

- ingestion of sporulated oocysts

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12
Q

T. gondii - protozoal stages in felids

A

Sexual stages in intestine (gametogony)
- fertilization –> unsporulated oocysts shed
Asexual stages: extraintestinal
- tachyzoites, bradyzoites

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13
Q

In the US ____ cats shed T gondii oocysts

A

1%

  • greater percentage have antibody titiers
  • oocyst re shedding is uncommon
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14
Q

Prepatent period

A

Time from infection until demonstration of oocysts in feces

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15
Q

T gondii - PPP

A
  • ingestion of tissue cysts (bradyzoites) –> 3-10 days (efficient)
  • ingestion of sporulated oocysts –> 20 days
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16
Q

Peak oocyst shedding occurs ______

A

6-7 days post infection

- oocyst shedding lasts 10-14 days, then decreases rapidly

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17
Q

T gondii - clinical signs

A

Subclinical
Feline toxoplasmosis
- concurrent infection, immunosuppression
- fever, weight loss, lethargy
- dyspnea, anorexia, abdominal discomfort, ichterus, retinochoroiditis, uveitis, encephalitis
- associated with multiple tachyzoites, granulomatous response
- multisystemic - primarily in lung, liver, ocular, brain

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18
Q

Cats with clinical disease are _______

A

Unlikely to be shedding oocysts

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19
Q

T gondii immune response is due to _______

A

Tachyzoites

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20
Q

Tissue cysts of T gondii contain ______

A

Bradyzoites

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21
Q

T gondii - sheep

A

Adults: major cause of sheep abortions in US via transplacental transmission (vertical)

22
Q

T gondii - goats

A

Adults: abortions, clinical toxoplasmosis (liver, kidney, CNS)

23
Q

T gondii - cattle

A

Resistant to infection

  • seropositive, but not important epidemiologically
  • tissue cysts are undetectable
24
Q

Other hosts of T gondii

A

Chickens: seropositive, with tissue cysts (not documented in commercial flocks, only backyard ones)
Swine: domestic and feral are seropositive, clincial signs are rare
Horses: resistant

25
Q

T gondii - dogs

A

Clinical toxoplasmosis is rare
- pneumonia, hepatitis, encephalitis
Vertical transmission is rare

26
Q

T gondii - wildlife

A

Seroprevalence high in many populations (esp white tailed deer)
- clinical toxoplasmosis in multiple species including: marsupials, non human primates

27
Q

T. gondii causes potential behavior changes in _______

A

Intermediate host

  • extended phenotype of the parasite
  • especially in murine hosts
  • depends on strains, age of host, stage of infection
28
Q

T gondii - diagnosis in felids

A
  • fecal float: rarely detects oocysts
  • subclinical
  • serology: does not predict shedding
  • IgM: peaks early (1-2 weeks PI)
  • IgG: develops 2 weeks PI
  • active infection requires demonstrating high titer
29
Q

T gondii - diagnosis in IH

A
  • clinical signs
  • antibody titers
  • PCR
  • immunohistochemistry
  • histology
30
Q

Tachyzoites are _______

A

Banana shaped

31
Q

T gondii - treatment/control

A

No vaccine or approved drugs

  • remove feces daily
  • do not feed cats raw food
  • prevent carnivorism
32
Q

T gondii - zoonosis

A 
Vulnerable populations
- pregnant women, immunosuppressed
Primary source of infection
- transplacental
- organ transplants
- meat sources
- raw goat milk
- environmental contamination
33
Q

T gondii - human pathology

A 
Immunocompetent patients
- aysmptomatic or flu-like
Immunocompromised
- neurologic infection
- exposure or reactivated dormant cyst = coma/death
Placental transmission
- abortion, hydrocephalus, blindness
- associated with schizophrenia
34
Q

Neospora caninum is similar to T gondii, except the DH is _______

A

Canids

  • neuromuscular disease
  • prevalent in strays, dogs around cattle
35
Q

N. caninum IH

A

Cattle (small ruminants)

- primary cause of cattle abortion worldwide

36
Q

Neospora caninum has a _____ life cycle only

A

Indirect

37
Q

N caninum - PPP

A

5-17 days

- oocysts sporulate in environment in 24-72 hrs = 2 sporocysts with 4 sporozoites each

38
Q

N caninum - route of infection

A

IH: oocyst, transplacental
DH: ingestion of tissue cyst, transplacental

39
Q

N caninum - pathology DH

A

Usually subclinical

  • congenitally infected puppies or immunocompromised
  • signs are neuromuscular
  • lesions: focal necrosis to severe myositis in skeletal muscles
40
Q

N caninum congenital infection leads to _______

A

Asymptomatic carriers

41
Q

N caninum - pathology IH

A

Cattle

  • abortions (abortion storms)
  • repeated abortions
  • infected calves that survive are asymptomatic carriers or have clinical infections
42
Q

N caninum - diagnosis

A 
DH
- fecal float for unsporulated oocysts
- antibody titers
IH 
- ELISA
- test aborted calves with PCR, ELISA
43
Q

N caninum - treatment and control

A

No approved treatment or vaccine

  • limit access of dogs to cattle
  • minimize fecal contamination
  • remove aborted fetus
  • herd management
44
Q

Hammondia

A

Must be distinguished from toxoplasma and neospora

  • oocysts are similar
  • is non-pathogenic
  • no extra-intestinal stage in IH
45
Q

Hammondia infects IH only via ____

A

Ingestion of oocysts

46
Q

Hammondia infects DH only via ________

A

Ingestion of tissue cysts

47
Q

Hammondia sites of infection

A

DH: intestinal tract only
IH: throughout entire body

48
Q

H. heydorni

A

DH: dog, coyotes
IH: herbivores

49
Q

H. hammondi

A

DH: cat
IH: mammals, birds

50
Q

Hammondia - life cycle

A
  • oocyst: 2 sporocysts with 4 sporozoites each
  • oocysts same size as toxo and neospora
  • PPP: 1 week
  • patent for 1-2 weeks
51
Q

Neospora hughesi

A

Less common cause of equine protozoal myelitis

  • primary cause is sarcocystis neurona
  • DH: unknown
  • IH: horse via transplacental

Parasitology (28 decks)

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