Parasitology coccidia

Question 1

“Coccidia”

Answer 1

A term that refers to many different parasites with similar life cycles
They all produce cysts in the feces called oocysts- diagnose by presence of these cysts
All stages in one host
important in chickens, dogs, cats, cattle, baby pigs, and rabbits

Question 2

Recently “coccidia” has also come to include parasites with a “coccidia” life cycle but in 2 hosts

Answer 2

Asexual stages in one host- the intermediate host

Then asexual and sexual stages-oocysts in another host- the definitive host

Question 3

The coccidia

Answer 3

All are intracellular parasites
In the phylum Apicomplexa
Their invasive stages have an apical complex composed of apical and polar rings, a conoid, and rhoptries
The apical complex in involved in cell penetration

Question 4

Eimeria and Cystoisopora, general

Answer 4

Fecal-oral transmission by oocysts
Extremely important in poultry, swine, and cattle production
Diarrhea, weight loss, and death can occur

Question 5

Eimeria species have ____ host(s).

Answer 5

one

cattle, sheep, goats, horses, rabbits, chickens

Question 6

Cystoisospora species have ____ host(s).

Answer 6

One; but most can use a paratenic host

dogs, cats, humans

Question 7

Extra-intestinal coccidia have ____ host(s).

Answer 7

2
Toxoplasma gondii usually has an intermediate host
Sarcocystis spp. MUST use an intermediate host

Question 8

Coccidia- site specific in the host

Answer 8

each species of coccidia has a specific location in the intestine where it will develop

Question 9

Multiplication in the host, asexual

Answer 9

Schizogony
A uninucleated stage becomes a multinucleate schizont and then cytoplasmic division occurs to produce individual parasites (merozoites)

Question 10

Multiplication in the host, sexual

Answer 10

Macrogamonts (female) and microgamonts (male) stages

Fertilization results in the production of a zygote that becomes the oocyst

Question 11

The oocyst

Answer 11

Environmentally resistant cyst stage (resistant to disinfectants)
Coccidia are identified based on the structure of their sporulated oocysts
It is often important to know what species is present b/c not all spp are pathogenic

Question 12

Oocysts are excreted ______. They _____ in the environment

Answer 12

unsporulated

sporulate

Question 13

Sporulated oocysts contain ______ which enclose the infective _______ which actively invade cells.

Answer 13

sporocysts

sporozoites

Question 14

What aspects of the oocyst are used to identify species

Answer 14

size, shape, color, number and appearance of sporocysts, numbers of sporoziotes in sporocysts, and ornamentations in oocysts wall

Question 15

Eimeria oocysts

Answer 15

sporulated oocysts have 4 sporocyts that each contain 2 sporozoites
There are 8 sporoziotes total per oocyst

Question 16

Cystoisospora oocysts

Answer 16

sporulated oocysts have 2 sporocysts which each contain 4 sporoziotes
There are 8 sporoziotes total

Question 17

Species that have Cystoisospora type oocysts

Answer 17

Toxoplasma gondii
Neospora caninum
Besnoitia spp
Sarcocystis spp
(Definitive and intermediate hosts)

Question 18

Prepatent period

Answer 18

Number of days it takes for oocysts to appear in the feces after the host ingests sporulated oocysts

Question 19

Patent period

Answer 19

Number of days that oocysts are excreted in the feces of the host
In the absence of re-infection coccidial infections are self limiting

Question 20

Pathogenicity

Answer 20

The rupture of infected cells and release of merozoites cause tissue destruction.
Villous atrophy- malabsorption
hemorrhage- blood loss
diarrhea- main clinical sign

Question 21

Pathogenicity depends on

Answer 21

species of coccidia present
number of oocysts ingested
age of host
environmental conditions (winter/stress induced coccidiosis in feedlot cattle)

Question 22

Diagnosis of coccidia

Answer 22

Clinical signs consistent with coccidiosis
Demonstrate oocysts of a pathogenic species
Demonstrate stages in intestines of dead animals (site specificity)
Rule out other causes of diarrhea

Question 23

Chicken coccidiosis

Answer 23

All anticoccidials are developed for use in chickens
Chicken cost more than beef prior to invention of anticoccidials
Coccidiosis cause decreased weight gains and feed conversion
Anticoccidial resistance a problem

Question 24

Bovine coccidiosis

Answer 24

Bloody diarrhea, weight loss, pneumonia, death (most less than 1 year old)
Stress induced coccidiosis- outbreaks that occur about 2 weeks after cattle are stressed

Question 25

Porcine coccidiosis

Answer 25

Diarrhea in 8-14 day old pigs, is fluid (fatty) but not bloody
Pigs continue to nurse, but may die before oocysts are excreted
Cystoisospora suis

Question 26

Dog and Cat coccidiosis

Answer 26

Diarrhea in young, sometimes bloody
Extraintestinal stages
Parantenic hosts
Toxoplasma, Neospora, Sarcocystis, Cryptosporidium
Spurious (non-infective) oocysts from eating prey or rabbit feces

Question 27

Spurious oocysts- dogs

Answer 27

May be elongate, may have a cap or other markings
May have a thick or rough wall
May not see any 2 celled oocysts

Question 28

Rabbit coccidiosis

Answer 28

Intestinal and HEPATIC

Hepatic coccidiosis: enlarged liver, bile duct hyperplasia, Eimeria stiedai