Parasitology coccidia Flashcards
“Coccidia”
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
Recently “coccidia” has also come to include parasites with a “coccidia” life cycle but in 2 hosts
Asexual stages in one host- the intermediate host
Then asexual and sexual stages-oocysts in another host- the definitive host
The coccidia
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
Eimeria and Cystoisopora, general
Fecal-oral transmission by oocysts
Extremely important in poultry, swine, and cattle production
Diarrhea, weight loss, and death can occur
Eimeria species have ____ host(s).
one
cattle, sheep, goats, horses, rabbits, chickens
Cystoisospora species have ____ host(s).
One; but most can use a paratenic host
dogs, cats, humans
Extra-intestinal coccidia have ____ host(s).
2
Toxoplasma gondii usually has an intermediate host
Sarcocystis spp. MUST use an intermediate host
Coccidia- site specific in the host
each species of coccidia has a specific location in the intestine where it will develop
Multiplication in the host, asexual
Schizogony
A uninucleated stage becomes a multinucleate schizont and then cytoplasmic division occurs to produce individual parasites (merozoites)
Multiplication in the host, sexual
Macrogamonts (female) and microgamonts (male) stages
Fertilization results in the production of a zygote that becomes the oocyst
The oocyst
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
Oocysts are excreted ______. They _____ in the environment
unsporulated
sporulate
Sporulated oocysts contain ______ which enclose the infective _______ which actively invade cells.
sporocysts
sporozoites
What aspects of the oocyst are used to identify species
size, shape, color, number and appearance of sporocysts, numbers of sporoziotes in sporocysts, and ornamentations in oocysts wall
Eimeria oocysts
sporulated oocysts have 4 sporocyts that each contain 2 sporozoites
There are 8 sporoziotes total per oocyst
Cystoisospora oocysts
sporulated oocysts have 2 sporocysts which each contain 4 sporoziotes
There are 8 sporoziotes total
Species that have Cystoisospora type oocysts
Toxoplasma gondii Neospora caninum Besnoitia spp Sarcocystis spp (Definitive and intermediate hosts)
Prepatent period
Number of days it takes for oocysts to appear in the feces after the host ingests sporulated oocysts
Patent period
Number of days that oocysts are excreted in the feces of the host
In the absence of re-infection coccidial infections are self limiting
Pathogenicity
The rupture of infected cells and release of merozoites cause tissue destruction.
Villous atrophy- malabsorption
hemorrhage- blood loss
diarrhea- main clinical sign
Pathogenicity depends on
species of coccidia present
number of oocysts ingested
age of host
environmental conditions (winter/stress induced coccidiosis in feedlot cattle)
Diagnosis of coccidia
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
Chicken coccidiosis
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
Bovine coccidiosis
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
Porcine coccidiosis
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
Dog and Cat coccidiosis
Diarrhea in young, sometimes bloody
Extraintestinal stages
Parantenic hosts
Toxoplasma, Neospora, Sarcocystis, Cryptosporidium
Spurious (non-infective) oocysts from eating prey or rabbit feces
Spurious oocysts- dogs
May be elongate, may have a cap or other markings
May have a thick or rough wall
May not see any 2 celled oocysts
Rabbit coccidiosis
Intestinal and HEPATIC
Hepatic coccidiosis: enlarged liver, bile duct hyperplasia, Eimeria stiedai
