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Flashcards in Apicomplexan 3 Deck (97):
1

What phase of Toxoplasma gondii is the quickly proliferating intracellular stage?

Tachyzoite

 

2

Which stage of Toxoplasma gondii is the slowly proliferating stage within tissue cysts?

Bradyzoite

3

Which stage of Toxoplasma gondii is inhibited by the immune response?

Tachyzoite

4

What are the 3 GENERAL modes of transmission of Toxoplasma gondii?

  1. Ingested of sporulated oocyst
  2. Transplacental
  3. Intermediate host

5

Toxoplasma gondii:

Tissue cysts with _____ in an intermediate host are infective.

Bradyzoites

6

Toxoplasma gondii:

Transplacental transmission by _____.

Tachyzoites

7

What is the definitive host of Toxoplasma gondii?

Cat

8

What is the primary means of transmission of Toxoplasma gondii?

Eating tissue cysts with bradyzoites

9

Where do merogony and gametogony occur for Toxoplasma gondii?

ONLY in the GI tract

10

True or False:

Toxoplasma gondii infected hosts shed sporulated oocysts in their feces.

 

FALSE

Oocysts are unsporulated

11

True or False:

  1. Toxoplasma gondii has an extra-intestinal phase.
  2. Sporulation of the unsporulated oocyst occurs in the environment over a period of about 10 days.

  1. TRUE
  2. FALSE - sporulation takes about 1-5 days

12

What type of replication occurs in the intermediate host of Toxoplasma gondii?

Extra-intestinal replication

13

Toxoplasma gondii:
Cysts with bradyzoites can be found in which parts of an intermediate host's body?

Eyes

Brain

Striated muscle

14

Toxoplasma gondii:
How would congenital infection occur?

Mother would have to be infected DURING the pregnancy, not before

15

Explain how a kitten might typically become infected with Toxoplasma gondii

Maternal antibody levels decline --> begin hunting --> ingest an intermediate host

16

When do cats typically shed oocysts when infected with Toxoplasma gondii?

Cats usually shed oocysts only ONCE in their lifetime following the primary infection

17

Why is congenital infection with Toxoplasma gondii uncommon?

Cats are typically exposed to Toxoplasma prior to pregnancy

18

Clinical toxoplasmosis is relatively uncommon in dogs.  In what populations of dogs might it be more common?

The young

The immunosuppressed

19

Explain the outcome of a congenital infection of Toxoplasma gondii in a small ruminant.  Why does the outcome vary?

Outcome varies depending on the stage of gestion when infection occurred/severity of that infection:

Early embryonic death

Fetal death and abortion

Stillbirth

Birth of weak offspring

Birth of congenitally infection normal offspring

20

Which 3 species are relatively resistant to toxoplasmosis?

Cattle

Horses

Camelids

 

21

True or False:
Toxoplasma gondii congenital infections are more severe in humans the later in gestation they occur.

FALSE

More severe the earlier in gestation they occur

22

Human Toxoplasma gondii infection:

What type of disease process might you see in an immune compromised individual?

Encephalitis

23

Q image thumb

Toxoplasma gondii: unsporulated oocyst from fresh cat feces

24

Q image thumb

Isosporid sporulated oocyst of Toxoplasma gondii

(NOT from fresh feces)

25

When you have reproductive loss in a small ruminant, what type of diagnostics might you want to run for Toxoplasma gondii?

  1. Check for gross lesions in placental cotyledons (multi focal grayish-white areas)
  2. Anti-Toxoplasma antibodies in fetal fluid
  3. Histopathology of fetal brain +/- placenta

26

  1. What are 2 drugs you could use to treat Toxoplasmosis in small animals?
  2. Which life cycle stage are those medications active against?

  1. Clindamycin & Pyremethamine
  2. Active against tachyzoites

27

What scenerio is the highest risk to humans for a Toxoplasma infection?

Seronegative human

+

Cat shedding oocysts

28

Which Toxoplasmosis scenerio poses the lowest risk to humans?

Seropositive human 

+

Cat not shedding oocysts

29

How might you prevent transmission of Toxoplasma to humans?

Prevent ingestion of tissue cysts:

  1. Wear gloves when handling raw meat
  2. Wash hands after handling raw meat
  3. Avoid unpasteurized goat milk
  4. Avoid undercooked deer meat

30

Which 3 meats are at highest risk for carrying Toxoplasma?

Lamb

Pork

Goat (chevron)

31

How might you help prevent/control a pregnant woman who owns a cat from getting infected with Toxoplasma?

Prevent oocyst sporulation & ingestion:

  1. Clean litter box daily
  2. Kill oocysts in litter box with boiling water
  3. Wash hands
  4. Wear gloves when gardening

32

How might you help prevent/control spread of Toxoplasma to a cat?

Prevent hunting (keep indoors)

Feed commercial cat food only (no raw meat)

Clean litter box daily

33

How might you help prevent/control spread of Toxoplasma to a small ruminant such as a sheep?

Decrease exposure of gestating ewes to oocysts:

  1. Keep cats out of feed sources
  2. Keep neutered cats only
  3. Minimize hunting by cats 

Keep only older ewes

Feed ewes monensin during gestation

34

What are the only known definitive hosts of Neospora caninum?

Dogs

Coyotes

35

What are some of the intermediate hosts of Neospora caninum?

Cattle

Sheep

Goats

Horses

Deer

36

True or False:
Neospora caninum has an extra-intestinal phase

TRUE

37

True or False:
The immune system is better at controlling a Neospora caninum infection that it is at controlling a Cryptosporidium infection.

FALSE

Immune system is better at controlling a Cryptosporidium infection.

38

What are the modes of transmission for Neospora caninum?

  1. Ingestion of tissue cysts with bradyzoites
  2. Transplacental transfer of tachyzoites

39

How does the intermediate host for Neospora caninum become infected?

Ingestion of sporulated oocysts

40

What is THE main mode of transmission of Neospora caninum?

Transplacental transfer of tachyzoites from dam to offspring

41

True or False:

  1. For Neospora caninum in dogs, merogony and gametogony occur in the intestine, similar to Toxoplasma in cats.
  2. For Neospora caninum, dogs shed sporulated oocysts in their feces.

  1. TRUE
  2. FALSE - shed NON-sporulated oocysts in their feces, similar to oocysts of Toxoplasma 

42

What causes the clinical signs associated with Neospora caninum?

Tachyzoites

43

Neospora caninum infects many cell types throughout the body, what are they?

Skin

Liver

CNS

Muscle

Kidneys

44

Which has a thicker cyst wall, Toxoplasma or Neospora caninum?

Neospora caninum

45

Neospora caninum:

Tachyzoites transform to bradyzoites as a result of what?

The immune response

46

Neospora caninum:

  1. What life stage forms tissue cysts?
  2. In what tissue will those cysts primarily be found?

  1. Bradyzoites
  2. CNS

47

Which organism is associated with a recrudescence of parasitemia from chronic infection?

Neospora caninum

48

Q image thumb

Neospora cyst

 

49

Q image thumb

Toxoplasma cyst

50

Neospora caninum:

  1. In cattle, there is inflammation of the placenta and fetus associated with what?
  2. In dogs, abortion is associated with what?

 

  1. Tachyzoites
  2. Tachyzoites

51

What is the cause of about 20% of cattle abortions worldwide?

Bovine neosporosis

52

What is the most common outcome of bovine neosporosis?

Live normal calf with congential infection

53

Bovine vertical tranmission is believed to be related to what?

Reactivation of parasites in cysts during pregnancy --> conversion of bradyzoites to tachyzoites --> transplacental transmission of tachyzoites

54

Upon necropsy of a calf with bovine neosporosis, which tissue might be necrotic?

Brain

Muscle

Placenta

55

Is Neosporosis a zoonotic disease?

NO

56

Bovine neosporosis:

  1. An endemic problem is most likely due to what?
  2. An abortion outbreak is most likely due to what?

  1. Endemic problem most likely due to transplacental infection
  2. Abortion outbreak more likely due to transmission via contamination of feed with oocysts from canine feces

57

Q image thumb

Hyperextension due to canine neosporosis

58

What are 2 drugs that can be used to help treat neosporosis in a pup?

Clindamycin

Pyremethamine + sulfdiazine

59

What is the cause of equine protozoal myeloencephalitis? (EPM)

Sarcocystis

60

What is the definitive host for sarcocystis?

Carnivore

61

What are the intermediate hosts for sarcocystis?

Herbivore 

Omnivores

62

In which host does sexual phase of sarcocystic occur?

Carnivore (definitive host)

63

In which host does the asexual phase for sarcocystis occur?

Herbivore, omnivore (intermediate host)

64

True or False:
Sarcocystis species have a wide range of defintive hosts and a narrow range of intermediate hosts.

TRUE

65

How does one become infected with Sarcocystis?

Ingestion of a tissue cyst

66

True or False:

Individuals with a Sarcocystic will shed sporulated oocytes in their feces.

TRUE

67

Sarcocystis:

What are the 2 phases within the intermediate host?

Vascular phase

Muscular phase

68

Q image thumb

Mature cyst of Sarcocystis hominis in bovine tongue muscle

 

Note: thick capsule consistent with Neospora + bradyzoites inside

69

Sarcocystis:

What type of clinical signs are seen in the vascular phase in a herbivore?

Fever

CNS disturbances

Abortion

Death

70

Sarcocystis:

What type of clinical signs are seen in the muscular phase in a herbivore?

Myositis

Myocarditis

CNS signs

Death

71

How does the definitive become infected with Sarcocystis?

Ingestion of bradyzoites from mature cysts in intermediate host

72

Sarcocystis:
What do bradyzoites infect?

Enterocytes

73

True or False:

Sarcocystis has NO proliferative phase.

TRUE

74

Where does gametogony occur for Sarcocystis?

Enterocytes of definitive host

75

True or False:

  1. Sarcocystic sporocytes OR sporulated oocysts can be shed in feces.
  2. Sarcocystis is immediately infective to an intermediate host in fresh feces.

  1. TRUE
  2. TRUE

76

Diagnosis of Sarcocystis in herbivore:

  1. Detection of schizonts in ____ of major organs.
  2. Detection of cysts in ____.

  1. Detection of schizonts in vasculature of major organs.
  2. Detect cysts in muscle (+/- CNS).

77

Diagnosis of Sarcocystis in a carnivore:

What 2 things might you be able to indentify in fresh feces?

Sporulated oocyst (with 2 sporocytes inside)

OR

Free sporocyst

A image thumb
78

How would you control/prevent an infection with Sarcocystis?

  1. Prevent dogs and cats from eating raw meat (animal carcasses)
  2. Prevent contamination of herbivore feed and water with dog or cat feces

79

What the cause of equine protozoal myeloencephalitis?

Sarcocystis neurona

80

True or False:

Sarcocystis neurona has a narrow definitive host range, but a broad intermediate host range/

TRUE

81

For Sarcocystis neurona, horses are the ____, ___ ___ host.

Aberrant, dead-end host

82

What is the ONLY definitive host for Sarcocystis neurona?

Opossum

83

What are the typical intermediate hosts for Sarcocystis neurona?

Cat

Raccoon

84

  1. Which host will develop tissue cysts with Sarcocystis neurona?
  2. Which host will not develop tissue cysts?

  1. Intermediate host = YES tissue cysts
  2. Opossum & horse = NO tissue cysts

85

Asymmetric muscle atrophy + neurologic signs

Sarcocystis neurona

86

What the risk factors for Sarcocystis neurona?

  1. Presence of opossums on farm
  2. Presence of woods on farm
  3. Occurrence of health stressor prior to signs
  4. Highest in the fall
  5. Increased number of horses on farm
  6. Use of wood chips or shavings for bedding
  7. Presence of rates, mice
  8. Increased human population density

87

How would you prevent/control spread of Sarcocystis neurona on your farm?

  1. Keep opossums from defecating in horse feed
  2. Trap and relocate opossums
  3. Remove carcasses of intermediate hosts
  4. Use anti-protozoal drugs prophylactically
  5. Monitor horses subjected to stress for early signs of EPM

88

Hepatozoon species:

Most species that parasitize mammals infect ___.

Leukocytes

89

Hepatozoon species:

Vertebrates become infected by...?

Ingesting an infected invertebrate

90

What is the transmission agent for American canine hepatozoonosis?

Amblyomma maculatum (Gulf coast tick)

91

What is the definitive host for Hepatozoon americanum?

Gulf coast tick (Amblyomma maculatum)

92

How is a dog infected with Hepatozoon americanum?

Ingestion of ticks infected with oocysts

93

Hepatozoon americanum:

Canines can become the intermediate hosts.  Merogony occurs in the ____, and early gametogony occurs in the ____.

Merogony occurs in the tissues.

Early gametogony occurs in the monocytes & macrophages.

94

Hepatozoon americanum:

  1. Tick takes up gamonts in ____ with a blood meal.
  2. ____ occur in the tick hemocoel.

  1. Tick takes up gamonts in monocytes / macrophages with a blood meal.
  2. Sporulated oocysts occur in the tick hemocoel.

95

What do you call the cysts that form due to a Hepatozoon americanum infection in a dog?

Onion skin cysts

96

What are the clinical signs of Hepatozoon americanum in a dog?

Fever

Myalgia

Myasthenia

Reluctance to move due to pain (due to myositis or periosteal vone proliferation)

Wasting

97