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Parasitology > Protozoa V: Apicomplexa Toxoplasma, Neospora > Flashcards

Protozoa V: Apicomplexa Toxoplasma, Neospora Flashcards

1
Q

Describe Toxoplasma gondii

A

Only species in the genus, but has many genotypes
Common
Can infect many vertebrates
Can cause multi-systemic disease, but can also be covert
Distributed worldwide

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2
Q

What is the definitive host of Toxoplasma gondii?

A

Felidae (domestic and wild)

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3
Q

What is the intermediate host of Toxoplasma gondii?

A

Almost all warm-blooded animals

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4
Q

What is the Toxoplasma gondii life cycle?

A

Tissue cysts from intermediate host is ingested by cat
Unsporulated oocysts passed in feces
Sproulates in 1-2 days
Sporulated oocysts in feed, water, or soil are ingested by intermediate host and warm-blooded vertebrates (cycle starts over with cat)
Warm-blooded vertebrates ingest contaminated food and water or uncooked meat
Tachyzoites are transmitted through the placenta

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5
Q

What parasites sporulate outside the host?

A 
Toxoplasma gondii
Hammondia
Isospora
Eimeria
Neospora
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6
Q

What parasites sporulate inside the host?

A

Sarcocystis

Cryptosporidium

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7
Q

What are the routes of infection with Toxoplasma gondii?

A

Ingestion of tissue cysts in IH

INgestion of sporulated oocysts

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8
Q

What are the Toxoplasma gondii protozoal stages in felids?

A

Sexual stages in intestine (gametogony): fertilization—unsporulated oocysts shed
Asexual stages are extra-intestinal (tachyzoites, bradyzoites)

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9
Q

What is a prepatent period?

A

Time from infection until demonstration of oocysts in feces

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10
Q

What is the PPP with ingestion of Toxoplasma gondii tissue cysts?

A

3-10 days (most efficient route)

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11
Q

What is the PPP with infestion of Toxoplasma gondii sporulated oocysts?

A

About 20 days

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12
Q

When is peak oocyst shedding of Toxoplasma gondii? How long does it last?

A

6-7 days post infection

Lasts about 10-14 day, then decreases rapidly

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13
Q

What are the clinical signs of Toxoplasma gondii in Felids?

A

Usually subclinical
Feline toxoplasmosis
Cats with clinical disease are unlikely to be shedding oocysts

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14
Q

What is Toxoplasma gondii a major cause of in adult sheep in the US?

A

Abortions

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15
Q

What is the transmission of Toxoplasma gondii in sheep?

A

Vertical transmission: congenitally infected offspring

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16
Q

What is Toxoplasma gondii associated with in goats?

A

Primarily abortions

Clinical toxoplasmosis

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17
Q

What is the transmission of Toxoplasma gondii in goats?

A

Vertical transmission: congenitally infected offspring

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18
Q

What is the transmission risk of Toxoplasma gondii between humans and goats?

A

Raw goat milk

Undercooked meat

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19
Q

Describe Toxoplasma gondii in cattle

A

Cattle are resistant to infection
Seropositive, but not epidemiologically important
No reports of clinical toxoplasmosis
Tissue cysts typically undetectable

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20
Q

Describe Toxoplasma gondii in chickens

A

Seropositive and have tissue cysts
Commercial flocks: clinical toxoplasmosis not documented
Backyard flocks: lesions and necrosis in brain

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21
Q

Describe Toxoplasma gondii in swine

A

Domestic and feral populations are seropositive

Clinical toxoplasmosis is rare

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22
Q

Describe Toxoplasma gondii in horses

A

Resistant: no reports of clinical cases

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23
Q

Describe Toxoplasma gondii in dogs

A

Clinical toxoplasmosis is rare

Vertical transmission rare

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24
Q

Describe Toxoplasma gondii in wildlife

A

Seroprevalence high in many wildlife populations
Clinical toxoplasmosis in multiple species including marsupials, non-human primates, etc.
Marine animals impacted from water run-off

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25
Q

What is seen in IH infected with Toxoplasma gondii?

A

Behavioral changes

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26
Q

What are the methods of diagnosis of Toxoplasma gondii in Felid definitve host?

A

Fecal float (rarely detects oocysts
Usually subclinical
Serology

27
Q

Describe serology for Toxoplasma gondii

A

Does not predict oocyst shedding
IgM peaks early
IgG develops 2 weeks post infection
Active infection requires demonstrating rising titer

28
Q

What are the methods of diagnosis of Toxoplasma gondii in the intermediate host?

A 
Clinical signs
Antibody titers
PCR
Immunohistochemistry
Histology
29
Q

What are methods of treatment for Toxoplasma gondii?

A

No vaccine

No approved drugs, but off-label options (Clindamycin hydrochloride)

30
Q

What are methods of control for Toxoplasma gondii?

A

Remove feces daily
Feed cats dry/canned/cooked meat only
Prevent carnivorism/hunting

31
Q

What are vulnerable populations that can be infected with Toxoplasma gondii?

A

Pregnant women

Immunosuppressed individuals

32
Q

What are the primary sources of infection of Toxoplasma gondii?

A 
Transplacental/transmammary
Organ transplants/blood transfusions
Meat sources
Raw goat milk*
Environmental contamination
33
Q

What is the pathology for Toxoplasma gondii in immunocompetent patients?

A

No symptoms to flu-like symptoms for a few weeks

34
Q

What is the pathology for Toxoplasma gondii in immunocomprised patients?

A

Most frequent neurological infections

Toxoplasma encephalitis

35
Q

What is the pathology for Toxoplasma gondii in the transmission from pregnant mother to unborn fetus?

A

Stillbirths, abortion, hydrocephalus, microcephalus, blindness
Congenital infections develop later in life

36
Q

What life cycle does Neospora caninum?

A

Indirect life cycle only

37
Q

How is Neospora caninum different from T. gondii?

A

DH: Canids
—Neuromuscular disease
—HIgh seroprevalence in strays and dogs around cattle
IH: Cattle
—Primary cause of cattle abortion worldwide
—Antibody titers in a wide range of hosts

38
Q

Describe the Neospora caninum life cycle

A

Definitive host: dog
Dogs can get reinfected
Sporulated oocysts in food, water, and soil are ingested by intermediate host
Dog ingests infected tissue cyst (e.g. in aborted fetus or infected calf)

39
Q

What is the PPP of Neospora caninum?

A

5-17 days
Oocysts sporulate in environment in 24-72 hours
When sporulated: 2 sporocysts/4 sporozoites each

40
Q

What are the routes of infection for Neospora caninum?

A

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

41
Q

What are the clinical signs and pathology of Neospora caninum in dogs (DH)?

A

Usually subclincial
Clinical infection
—Congenitally infected puppies or immunocompromised dogs
—Signs are usually neuromuscular
—Lesions: focal necrosis to sever myositis in skeletal muscles
Congenital infection—asymptomatic carriers

42
Q

What are the neuromuscular signs associated with Neospora caninum?

A

Progressive hind limb paralysis
Muscle atrophy
Difficulty swallowing

43
Q

What are the clinical signs and pathology of Neospora caninum in IH?

A

Cattle:
Abortions (Abortion storms; stillbirths)
Infected calves that survive are asymptomatic carriers or have clinical infection

44
Q

What is the method of diagnosing Neospora caninum in DH?

A

Fecal flotation: unsporulated oocysts

Antibody titers in dogs vary widely

45
Q

What is the method of diagnosing Neospora caninum in IH?

A

Cattle: antibody test using serum or milk (ELISA); multiple testing
Aborted calves: brain, fetal fluid, placental tissue collected for histology
Other hosts: histology

46
Q

What are the methods of treatment of Neospora caninum?

A

No approved treatment

No vaccine available

47
Q

What are methods of control of Neospora caninum?

A

Limited access of dogs to cattle
Minimize fecal contamination, by dogs, of food and water
Remove aborted cattle fetus/placenta/stilbirths
Herd management: culling. testing

48
Q

What must Hammondia be distinguished from? Why?

A

Toxoplasma and Neospora

Oocysts have similar appearance/size

49
Q

What makes Hammondia different from Toxoplasma and Neospora?

A

It is non-pathogenic
Has no extra-intestinal stage in DH
Infects IH only via ingestion of oocysts
Infects DH only via ingestion of tissue cysts

50
Q

What is the DH of Hammondia heydorni?

A

Dogs, coyotes

51
Q

What is the IH of Hammondia heydorni?

A

Herbivores

52
Q

What is the DH of Hammondia hammondi?

A

Cat

53
Q

What is the IH of Hammondia hammondi?

A

Mammals, birds

54
Q

What is the site of infection in hosts with Hammondia?

A

DH: intestinal tract only
IH: throughout entire body

55
Q

Where does Hammondia sproulate?

A

Outside the host

56
Q

What is the treatment for Hammondia?

A

None

57
Q

What is the control for Hammondia?

A

Proper sanitation

58
Q

What is the pathology for Hammondia?

A

None

59
Q

What is the Hammondia oocyst like?

A

2 sporocysts with 4 sporozoites each

60
Q

What is the PPP for Hammondia?

A

1 week

61
Q

How long is Hammondia patent?

A

1-2 weeks

62
Q

What is Neospora hughesi the less common cause of?

A

Equine Protozoal Myelitis

63
Q

Describe the life cycle of Neospora hughesi

A 
Poorly understood
DH: unknown
IH: horse
---Transplacental transmission
---Clinical signs and treatment similar to EPM

Parasitology (27 decks)

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