Protozoa- Apicomplexa 4: Plasmodium, Babesia, & Sarcocystis

Question 1

What are the characteristics of the genus Sarcocystis?

Answer 1

Tissue cyst forming, ubiquitous in mammals, birds, and reptiles; free oocyst in feces, sporulate in intestine of definitive host; named for their host (e.g., S. bovicanis, S. ovicanis, S. suihominis).

Question 2

Describe the pathogenesis of Sarcocystis.

Answer 2

Usually apathogenic; occasionally zoonotic self-limiting diarrhea can be seen; some species have very large, visible cysts.

Question 3

What are the hosts of S. neurona?

Answer 3

Definitive: opossums; Intermediate: armadillos, skunks, raccoons, and other animals; Aberrent (dead-end): horses.

Question 4

Describe S. neurona in horses.

Answer 4

Can result in EPM; tropism for development of bradyzoite cysts in neurological tissue; more common than N. hughesi.

Question 5

What is EPM?

Answer 5

Progressive neurological disease of horses resulting from schizogony of Sarcocystis in neurons.

Question 6

Where is EPM found?

Answer 6

North, south, and central America.

Question 7

In what kind of horses is EPM most common?

Answer 7

Arises sporadically mostly in younger horses less than 4 months old.

Question 8

Describe the neurological signs of EPM in horses.

Answer 8

Varying depending on whether the brain, brainstem, or spinal cord are affected.

Question 9

What are the initial clinical signs of EPM?

Answer 9

Dysphagia, abnormal upper airway function, unusual or atypical lameness, or even seizures.

Question 10

What are the clinical signs of EPM seen in severely affected horses?

Answer 10

Difficulty standing, walking, or swallowing; the disease can progress very rapidly.

Question 11

True or false: Occasionally, the clinical signs of EPM stabilize, only to relapse days or weeks later.

Answer 11

True.

Question 12

Describe the diagnosis techniques of EPM.

Answer 12

Differential is difficult; rule out other causes; test CSF for antibodies against S. neurona or N. hughesi; definitive diagnosis possible on post-mortem exam.

Question 13

What is the treatment for EPM?

Answer 13

Ponazuril or similar, sulfonamide/pyrimethamine plus anti-inflammatories.

Question 14

What are the characteristics of Besnoitia?

Answer 14

Both tissue-cyst forming and vector-borne; low morbidity/mortality in endemic areas; higher numbers of clinical cases in emerging areas: 1% mortality.

Question 15

What are the clinical signs of severe acute Besnoitia in cattle?

Answer 15

Pyrexia, subcutaneous edema, stiffness of the limbs due to swollen joints; conjunctivitis, nasal discharge, photophobia, inspiratory dyspnoea, reduced milk yield, and orchitis in bulls.

Question 16

What are the clinical signs of chronic Besnoitia in cattle?

Answer 16

Skin lesions, the presence of macroscopic scleral conjunctival and vestibulo-vulval cysts, and a gradual deterioration in body condition.

Question 17

What are the methods of diagnosis of Besnoitia in cattle?

Answer 17

Histopathology characteristic cysts in skin biopsies; molecular techniques; ELISA; clinical signs.

Question 18

What are the characteristics of Besnoitiosis in equids?

Answer 18

Emerging disease in Europe, recognized in USA; clinical signs mostly in donkeys; usually non-fatal.

Question 19

What are the clinical signs of Besnoitiosis in equids?

Answer 19

Multi-focal white miliary nodular lesions in the skin - over the face and body, within the nares, on the internal and external pinnae, vulva, perineum, and on the legs.

Question 20

What is the most common and unique feature of Besnoitiosis in equids?

Answer 20

The presence of scleral and conjunctival parasitic cysts - ‘scleral pearls.’

Question 21

What are the general characteristics of Babesia genus?

Answer 21

Tick vectors are required hosts; mammalian stages found within RBCs; size, appearance, and arrangement particular to different species; clinically important in several veterinary species with high public health relevance.

Question 22

What are the important Babesia spp in cattle?

Answer 22

B. divergens, B. major, B. bovis, B. bigemina.

Question 23

What are the important Babesia spp in dogs?

Answer 23

B. canis, B. vogelli, B. gibsoni, B. vulpes (B. microti).

Question 24

What are the important Babesia spp in humans?

Answer 24

B. microti; others in splenectomized people.

Question 25

What is the common Babesia species in horses?

Answer 25

B. caballi.

Question 26

What is the important Babesia species in cats?

Answer 26

B. felis.

Question 27

What are the two spp of bovine Babesia in tropical areas and what tick acts as their vector?

Answer 27

B. bovis and B. bigemina, with Rhipicephalus ticks acting as their vector.

Question 28

What are the two spp of bovine Babesia in temperate areas and what tick acts as their vector?

Answer 28

B. divergens: Ixodes ricinus tick; B. major: Hymorphysalis punctata tick.

Question 29

Bovine babesiosis in North America is referred to as what?

Answer 29

"Cattle fever"; sustained efforts aimed at controlling "cattle fever ticks."

Question 30

Surveillance for bovine babesiosis is common where?

Answer 30

USA along the border with Mexico.

Question 31

Describe the role of biting insects in transmission of Besnoitia.

Answer 31

Biting insects are thought to be mechanical vectors in the horizontal transmission from one bovine to another.

Question 32

Describe the life cycle of Babesia.

Answer 32

3 host tick bites vertebrate and obtains pre-gametocytes; adult tick imparts transovarial transmission and then the larval, nymph, and adult stages all undergo transstadial transmission with sporozoite differentiation at each stage; tick bites vertebrate and transfers sporozoites to the definitive host.

Question 33

What are the clinical signs of bovine babesiosis?

Answer 33

Anemia/hemoglobinuria due to destruction of RBCs; reverse age resistance; fever, depression, milk drop, abortion; congested, pale, icterus MM.

Question 34

What is the treatment for bovine babesiosis?

Answer 34

Antiprotozoal drugs (imidocarb dipropionate); supportive therapy such as fluids, blood transfusion, NSAIDs, or steroids.

Question 35

What are the control methods for bovine babesiosis?

Answer 35

Tick control; chemical prophylaxis; vaccine potential for both the parasite and tick vectors; quarantine and biosecurity.

Question 36

What Babesia species cause canine babesiosis?

Answer 36

B. canis, B. vogeli, B. gibsoni, B. vulpes, B. conradae.

Question 37

What tick is the vector for canine babesiosis?

Answer 37

Rhipicephalus sanguineus.

Question 38

Canine babesiosis is enzootic where?

Answer 38

In the USA.

Question 39

What is the incubation period for canine babesiosis?

Answer 39

10-28 days.

Question 40

What are the clinical signs of canine babesiosis?

Answer 40

Thrombocytopenia; hemolytic anemia; parasites may persist after clinical resolution and recrudescence is seen with immunosuppression.

Question 41

How do you diagnose canine babesiosis?

Answer 41

Blood smear or PCR.

Question 42

What is the treatment for canine babesiosis?

Answer 42

Imidocarb dipropionate or atovaquone.

Question 43

What are the prevention/control methods for canine babesiosis?

Answer 43

Regular administration of acaricides.

Question 44

Zoonotic babesiosis is due to what species?

Answer 44

B. microti (rodent species) and occasionally other species following a splenectomy.

Question 45

Where are most cases of zoonotic babesiosis seen?

Answer 45

US northeast, upper midwest seasonally during tick activity; only a small number of cases are clinically significant.

Question 46

What is the tick vector of zoonotic babesiosis?

Answer 46

Ixodes scapularis.

Question 47

What is the control for zoonotic babesiosis?

Answer 47

Take care when walking: cover up in wooded areas and check yourself for ticks.

Question 48

Theileria is globally important in what animals?

Answer 48

Farm animals; significant for equine movement trade and competition.

Question 49

What are the characteristics of Theileria spp?

Answer 49

Common in farm animals; most species (except T. equi) are only in tropical areas; can transform or immortalize lymphocytes.

Question 50

What are the important cattle Theileria spp?

Answer 50

T. annulata, T. parva, T. sergetti.

Question 51

What do cattle Theileria spp. cause and where are they found?

Answer 51

Cause "East Coast Fever" in sub-Saharan Africa.

Question 52

What are the common Theileria spp of equids?

Answer 52

T. equi.

Question 53

What does equine Theileria species cause?

Answer 53

Equine Piroplasmosis.

Question 54

What is the Theileria species of cats?

Answer 54

Cytauxzoon felis.

Question 55

What happens when Theileria enters the host after tick feeding?

Answer 55

Sporozoite attachment to host lymphocytes, where it enters the lymphocyte and proliferates into many infected cells; ruptured lymphocytes allow piroplasms to infect RBCs which are taken up by ticks upon feeding.

Question 56

East Coast Fever has up to _____% mortality in introduced cattle.

Answer 56

100%, significantly less in endemic areas and local breeds.

Question 57

What is the incubation period of East Coast Fever?

Answer 57

8 days.

Question 58

What are the clinical signs of East Coast Fever?

Answer 58

Pyrexia, lymphadenopathy, anemia, respiratory and neurological complications.

Question 59

What are the control methods for East Coast Fever?

Answer 59

"Vaccine" that injects viable parasites and anti-parasitic drug simultaneously to induce cytotoxic T cell response; recombinant vx in development; tick protection.

Question 60

How does one get equine piroplasmosis?

Answer 60

Tick bite or iatrogenic transmission.

Question 61

When do clinical signs of equine piroplasmosis present?

Answer 61

1-3 weeks post infection.

Question 62

What are the symptoms of horses with equine piroplasmosis?

Answer 62

Acute phase: pyrexia, hemolytic anemia, thrombocytopenia, petechiae, icterus, edema, systems involvement; rarely: sudden death; carrier state is inapparent.

Question 63

How do you diagnose equine piroplasmosis?

Answer 63

Clinical signs and pathological features; serology, blood smear, PCR.

Question 64

What is the treatment for equine piroplasmosis?

Answer 64

Parasite clearance with imidocarb; quarantine measures; major issue for traveling horses.

Question 65

What are the control methods for equine piroplasmosis?

Answer 65

Horse movement controls; tick control; take care with needles to prevent iatrogenic transmission.