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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
T gondii - dogs
Clinical toxoplasmosis is rare - pneumonia, hepatitis, encephalitis Vertical transmission is rare
26
T gondii - wildlife
Seroprevalence high in many populations (esp white tailed deer) - clinical toxoplasmosis in multiple species including: marsupials, non human primates
27
T. gondii causes potential behavior changes in _______
Intermediate host - extended phenotype of the parasite - especially in murine hosts - depends on strains, age of host, stage of infection
28
T gondii - diagnosis in felids
- 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
T gondii - diagnosis in IH
- clinical signs - antibody titers - PCR - immunohistochemistry - histology
30
Tachyzoites are _______
Banana shaped
31
T gondii - treatment/control
No vaccine or approved drugs - remove feces daily - do not feed cats raw food - prevent carnivorism
32
T gondii - zoonosis
``` Vulnerable populations - pregnant women, immunosuppressed Primary source of infection - transplacental - organ transplants - meat sources - raw goat milk - environmental contamination ```
33
T gondii - human pathology
``` 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
Neospora caninum is similar to T gondii, except the DH is _______
Canids - neuromuscular disease - prevalent in strays, dogs around cattle
35
N. caninum IH
Cattle (small ruminants) | - primary cause of cattle abortion worldwide
36
Neospora caninum has a _____ life cycle only
Indirect
37
N caninum - PPP
5-17 days | - oocysts sporulate in environment in 24-72 hrs = 2 sporocysts with 4 sporozoites each
38
N caninum - route of infection
IH: oocyst, transplacental DH: ingestion of tissue cyst, transplacental
39
N caninum - pathology DH
Usually subclinical - congenitally infected puppies or immunocompromised - signs are neuromuscular - lesions: focal necrosis to severe myositis in skeletal muscles
40
N caninum congenital infection leads to _______
Asymptomatic carriers
41
N caninum - pathology IH
Cattle - abortions (abortion storms) - repeated abortions - infected calves that survive are asymptomatic carriers or have clinical infections
42
N caninum - diagnosis
``` DH - fecal float for unsporulated oocysts - antibody titers IH - ELISA - test aborted calves with PCR, ELISA ```
43
N caninum - treatment and control
No approved treatment or vaccine - limit access of dogs to cattle - minimize fecal contamination - remove aborted fetus - herd management
44
Hammondia
Must be distinguished from toxoplasma and neospora - oocysts are similar - is non-pathogenic - no extra-intestinal stage in IH
45
Hammondia infects IH only via ____
Ingestion of oocysts
46
Hammondia infects DH only via ________
Ingestion of tissue cysts
47
Hammondia sites of infection
DH: intestinal tract only IH: throughout entire body
48
H. heydorni
DH: dog, coyotes IH: herbivores
49
H. hammondi
DH: cat IH: mammals, birds
50
Hammondia - life cycle
- oocyst: 2 sporocysts with 4 sporozoites each - oocysts same size as toxo and neospora - PPP: 1 week - patent for 1-2 weeks
51
Neospora hughesi
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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