Apicomplexa

Question 1

Apicomplexa - general characteristics

Answer 1

All have “apical complex” in infective stage (helps host cell invasion)

• widely diverse, infecting intestinal tissue and extraintestinal, blood, etc
• unicellular
• direct/indirect, asexual/sexual, predator/prey, or vector bone life cycle

Question 2

Apicomplexa - intestinal stages

Answer 2

• Eimeria
• Isospora suis
• Cryptosporidium
• Toxoplasma gondii

Question 3

Apicomplexa - extraintestinal stages

Answer 3

• Cytoisospora
• Sarcocystis cervi, neurona
• Toxoplasma gondii
• Hepatazoon americanum

Question 4

Apicomplexa - blood stages

Answer 4

• Babesia
• Cytauxzoon felis
• Hepatozoon
• Plasmodium
• Haemoproteus
• Leucocytozoon

Question 5

Sporogony

Answer 5

Asexual reproduction

• single zygote (in oocyst) produces infective sporozoites
• formation of infectious stages of parasite

Question 6

Merogony (schizogony)

Answer 6

Asexual reproduction

• sporozoites undergo rapid division to become meront (schizont) stages containing invasive merozoites
• several generations possible, depending on species

Question 7

Gametogony (gamogony)

Answer 7

Merozoites differentiate into gametes

- male microgametes and female macrogametes

Question 8

Fertilization

Answer 8

Gametes fuse to produce zygote (oocyst)

Question 9

Coccidian - generic life cycle

Answer 9

Zygote –> sporogony = sporozoites –> host cell invasion –> merozoites –> merogony/schizongony OR –> gamogon = gametes –> fertilization

Question 10

Eimeria spp. - coccidia

Answer 10

• original description based on: host species, host location, oocyst morphology
• cosmopolitan distribution
• host and site specific (usually)

Question 11

Which Eimeria species are pathogenic in cattle?

Answer 11

• E. bovis

- E. zuernii

Question 12

Which Eimeria species are pathogenic in chickens?

Answer 12

• E. tenella

- E. maxima

Question 13

Eimeria - oocysts

Answer 13

Unsporulated when released in feces

• sporogony occurs in environment
• sporulated oocyst = 4 sporocytes, each with 2 sporozoites (total of 8 infectious units per cyst)

Question 14

Eimeria - sporulated oocyst

Answer 14

Ingested

• sporozoites infect target cells
• merogony (merozoites)
• gametogony (gametes)
• gametes fuse = oocyst production

Question 15

Eimeria has a _____ life cycle

Answer 15

Direct

• host –> environment –> host
• completed in a single host!

Question 16

Eimeria - pathology

Answer 16

• severe, watery diarrhea, dehydration
• bloody feces
• weight loss
• lethargy/depression

Question 17

Pathogenesis of eimeria leaves a ______ number of oocysts in fecal floatations.

Answer 17

High!

- once oocysts are present, damage has been done

Question 18

Eimeria - cattle

Answer 18

Pathogenic: E. bovis, E. zuernii

• PPP: 2-3 weeks
• clinical signs: severe, watery diarrhea, weight loss, lesions, submucosa destroyed

Question 19

Nervous coccidiosis is associated with _____

Answer 19

Eimeria zuernii

Question 20

Eimeria - small ruminants

Answer 20

Pathogenic (sheep): E. ahsata, E. ovina

- host specificity?

Question 21

What species are not infected with Eimeria?

Answer 21

Dogs and cats

Question 22

Which species are asymptomatic with Eimeria?

Answer 22

Horses

- E. leuckarti

Question 23

Eimeria diagnosis

Answer 23

• clinical signs
• lesions: direct smear, lesion scoring, histology
• fecal exam: sugar float

Question 24

When identifying the oocyst you do NOT want to _______

Answer 24

Refridgerate the sample

• will delay sporulation, which requires 48 hours
• use 2.5% potassium dichromate for storage

Question 25

Anticoccidials

Answer 25

Prophylactic treatment - wide range - coccidiostat vs coccidiocidal - rotation/shuttle programs - stress in young animals

Question 26

Are coccidia vaccines available?

Answer 26

Yes, live strains for poultry industry - attenuated - in ovo vaccination (live oocysts)

Question 27

Other ways to control Eimeria

Answer 27

- environment: sanitation, litter management | - animal: monitoring, mixed ages, prophylactic treatment program

Question 28

Cystoisospora can have extraintestinal stage in _______

Answer 28

Paratenic hosts - monozoic tissue cyst - commonly infect dog/cat

Question 29

Isospora is strictly ______

Answer 29

Intestinal

Question 30

Isospora/cystoisospora ______ life cycle

Answer 30

Direct - unsporulated oocysts shed in environment --> sporogony --> sporulated oocysts - DH ingests sporulated oocysts --> sporozoites release --> infect target cells

Question 31

What differentiates isospora/cystoisospora from eimeria?

Answer 31

Isospora/cystoisospora have sporulated oocysts with: | - 2 sporocysts with 4 sporozoites each

Question 32

Isospora/cystoisospora asexual stages

Answer 32

Sporozoites invade host intestinal cell undergo merogony --> merozoites form --> invade new host cell --> second generation of merozoites --> invade new cells

Question 33

Isospora/cystoisospora sexual stages

Answer 33

Gametogony (gamogony) | - male/female gametes --> fertilization --> oocysts produced --> passed in feces unsporulated

Question 34

Cystoisospora indirect life cycle

Answer 34

Unsporulated oocysts shed in environment --> sporogony --> sporulated oocysts (2 sporocysts w/ 4 sporozoites each) - DH ingests sporulated oocysts OR paratenic host with monozoic cysts --> sporozoites released --> infect intestinal cells

Question 35

Cystoisospora indirect asexual stages

Answer 35

Sporozoites invade host intestinal cell undergo merogony --> merozoites formed --> invade new host cell --> second generation of merozoites --> invade new cells

Question 36

Cystoisospora indirect sexual stages

Answer 36

Gametogony (gamogony) | - male/female gametes --> fertilization --> oocysts produced --> passed in feces unsporulated

Question 37

Cystoisospora - paratenic host

Answer 37

Ingests sporulated oocysts --> extraintestinal development of monozoic cysts

Question 38

Isospora/cystoisospora PPP

Answer 38

At least 1 week for most species | - may be longer in monozoic cysts is infection route

Question 39

Isospora suis

Answer 39

Neonatal porcine coccidiosis - ubiquitous in closed confinement - 15-20% of swine diarrhea - sows do not have clinical disease, just neonates

Question 40

Isospora suis - clinical signs

Answer 40

- diarrhea: pasty yellow, fluid after 2-3 days - dehydration - lethargy - destruction of villous epithelium in SI: malabsorption - recovery: resistance

Question 41

I. suis PPP

Answer 41

5 days | - oocysts shed 1-3 weeks

Question 42

I. suis diagnostics

Answer 42

Fecal oocysts - fecal float - 48 hr sporulation (required to differentiate from eimeria) PM diagnosis - intestinal scrapings of lesions, wet mount

Question 43

I. suis control

Answer 43

- place sows on anticoccidial during 3rd trimester - steam clean - anticoccidials - albon, baycox

Question 44

Cystoisospora spp - dogs

Answer 44

Ubiquitous in young dogs - host specific - diarrhea, dehydration, anorexia - asexual/sexual stages destroy intestinal cells

Question 45

Isospora/cystoisospora - cats

Answer 45

More pathogenic in cats 4 weeks or younger - diarrhea, dehydration, malnutrition, death - moderate or subclinical in older cats

Question 46

Isospora/cystoisospora oocyst rule outs

Answer 46

Cats: cryptosporidium, hammondia, t. gondii Dogs: cryptosporidium, hammondia, neospora caninum, sarcocystis

Question 47

Isospora/cystoisospora sporulation _____

Answer 47

16 hours

Question 48

Isospora/cystoisospora - control

Answer 48

Dog/cats - disingestion of paratenic hosts - sanitation - treat all animals - anticoccidials