Protozoa I - Coccidia Flashcards
Review this image:
Simplified and selective protozoa classification
Describe protozoa in general.
„Proto – zoa“ – first animals,
Single celled Eukaryotes (1-150 μm)
No cell wall, but cell membrane.
Heterotrophs that feed off organic compounds.
Pinocytosis, phagocytosis, mouth (cytostome).
More than 50 000 species
Mostly free-living species
Describe Protozoa motility.
Motility through flagella, cilia, amoebic, alveolata.
Protozoa life form nomenclature.
- zoite
Eg. trophozoite, sporozoite, merozoite, bradyzoite, tachyzoite. - moving, infective, invasive
- feeding, reproducing
“-ont”
- a “bag” of zoites
- meront (=schizont), gamont
- intracellular
Cyst (oocyst)
- resting
- non-motile, stable
Protozoa life cycle type.
Monoxenous (one host cylce) or heteroxenous (two or more hosts in life cycle, this is more common).
In heteroxenous life cycle, arthropod vectors are often second hosts, as well as birds or mammals.
Describe protozoa reproduction.
Asexual reproduction - many possible variations.
Sexual reproduction - gametogony.
Metagenesis when there is both sexual and asexual reproduction. (eg.Eimeria spp.)
Sporogony = sporulation which is a type of asexual reproduction.
define sporozoa
a group of parasitic protozoans that includes *Plasmodium, the malaria parasite.
Most sporozoans do not have cilia or flagella.
define schizogony
asexual reproduction by multiple segmentation characteristic of sporozoans (as the malaria parasite)
define gametogeny
the formation and maturation of gametes
define sporogeny
sporulation
the multiple fission of an encysted zygote or oocyte, resulting in the formation of sporozoites.
Sporozoites are inside a sporocyst
Outside in the environment
flagellated protozoa higher group is officially known as
Excavata
Asexual reproduction – binary fission
Some produce cysts
Flagella and undulating membrane for moving
Kinetoplast (mitochondrial DNA) binding the flagella
Important Orders that belong to Excavata: (3)
- Trypanosomatida
- Diplomonadida
- Trichomonadida
Phylum Apicomplexa are what type of protozoa
sporozoa
Life cycle complex - metagenesis
- asexual and sexual multiplication
- sporogony - produce oocysts
Mostly intracellular parasites
- apical complex helps to get in the cell
3 Important Orders to belong to phylum apicomplexa:
- Cryptosporidia
- Eimeriida
- Piroplasmida
What is TSAR?
Also known as phylum apicomplexa or alveolata.
What phylum and class do Eimeria belong to?
Phylum Apicomplexa
Order Coccidea
define
Eimeriosis;
coccidiosis
Genera Eimeria and Isospora/ Cystoisospora (Synonyms)
eimeriosis -disease caused by Eimeria spp.
coccidiosis -disease caused by Eimeria and Isospora
Eimeriosis is caused by?
Where is it found?
Who does it invade?
Parasite: protozoa,
Apicomplexan Eimeria spp.
Prevalent worldwide.
Many-many hosts! But hosts are eimaria spp. specific.
Also, Very site-specific!
Three important stages in eimeria spp. life cycle:
All 3 of the following repro. strategies are ALWAYS present.
- Asexual schizogony (merogony) - schizont (bag of merozoites).
- Sexual gametogony – gamont (always occurs in the host).
- Sporulation – sporozoites form inside oocysts.
Transmission – fecal-oral (sporulated oocysts).
Eimeria spp. life cycle
Sporulated oocysts causes infection.
Oocysts encyst in SI where sporozoites are released.
When they enter enterocytes, they develop into trophozoites.
Then schizogony/merogony takes place (trophozoites into schizonts).
Merozoites are formed (inside schizonts??). Merozoites spread, and then initiate gametogeny which is the cause of clinical disease.
Unsporulated oocysts are not
infectious
Sporulated oocysts are infectious.
Sporulation takes 2-5 days (with a few exceptions).
Oocyst are very resistant in the environment (up to one year) and very resistant to many disinfectants.
Sporulated Eimeria spp. always have how many sporocysts and each with how many sporozoites?
Sporulated Eimeria spp. has always 4 sporocysts and each with 2 sporozoites.
Eimeriosis pathogenesis is due to
intracellular multiplication, host immune reaction.
Some species highly pathogenic.
Young animals most susceptible to clinical disease.
Eimeriosis clinical signs
Signs vary from poor weight gain to sudden death.
- diarrhea (watery, mucous, bloody) - mostly in young animals
- dehydration
- loss of weight, anaemia, apathy, possible death
Manifestation of coccidiosis in
● Individual animal versus
● Herd/flock
● Individual animal:
○ asymptomatic/non-clinical disease - but large numbers of oocysts in feces.
or
○ acute, severe, fatal, bloody diarrhea - but no oocysts in feces - prior to patency.
● Herd/flock
○ regularly occurring diarrhea problems with every new cohort of young animals.
Chicken eimeriosis is caused by
Pathogenic spp. are E.brunetti, E.necratrix, E.tenella.
They each affect a diff. portion of the GI tract.
Describe Chicken eimeriosis.
+ e.g. risk factors
Very important infectious disease in chickens due to high economic losses high.
- young birds at greatest risk
Risk factors
- Intensive husbandry
- High stocking density (especially in broiler houses)
- Bad quality litter – too much moisture
- Lighting schedule – intermittent lighting increases risk
- Antinutritional factors
Describe Rabbit eimeriosis: Liver and biliary tract eimeriosis,
Species: E. stiedae in the bile ducts of liver.
Prepatent period 2-3 weeks.
Liver and abdomen enlargement – jaundice, stomach hard when palpated, back slimming, apathy, thirsty
High mortality – very pathogenic.
Diagnosis of eimeriosis.
Anamnesis and clinical signs.
Fecal flotation method in which there must be many oocysts to be diagnostic (species differentiation also possible with PCR.
Diagnostic finding of OPG can begin from
5000 OPG to 100 000 OPG. (oocysts per gram of feces)
+ Histopathology
+ Post mortem analysis
Mixed infections with trichostrongyloid nematodes are common.
Histopathology in eimeriosis diagnostics.
- rectal mucosal smear
- Post mortem intestine mucosal smear
Eimeria different stages:
- schizont (merozoites inside)
- macrogametocytes
- immature oocysts
Hemorrhages
Genus Cystisospora belongs to what family?
Family Sarcocystidae
Order Eimeriida
Class Coccidea
Phylum Apicomplexa
Cystoisospora spp. cause what disease in dogs and cats?
cystoisosporosis
cystisospora and isospora are essentially synonyms so don’t let this mix you up
technically belong to diff families, however, share so many similarities, in practice they are interchangeable.
Describe Cystoisospora spp. in general.
Worldwide prevalence
Localizes in small and large intestine.
Problem in kennels and animal shelters.
Species and hosts:
Dogs:
C. canis , C. ohioensis, C. burrowsi, C. neorivolta
Cats:
C. felis , C. rivolta
Paratenic hosts: rodents, birds, and other animals.
NOT zoonotic
Cystoisospora spp. life cycle
Monoxenous or facultatively heteroxenous.
Sporulated oocyst or dormozoite from prey infects the final host.
Sporozoites then invade epithelial cells.
Reproduction then occurs via multiple methods.
repeated merogony (asexual division)
gametogony (sexual replication)
shedding non-sporulated oocysts
sporulation outside (1+ days)
Paratenic host is infected with extraintestinal dormozoites (sporozoites) in liver, spleen, lymph nodes.
Cystoisospora spp. of Dogs:
C. canis , C. ohioensis, C. burrowsi, C. neorivolta
Cystoisospora spp. of Cats:
C. felis , C. rivolta
Diagnosis of cystoisosporosis.
Detecting oocysts in fecal flotation (requires multiple sampling days due to sporadic shedding).
Oocysts resemble other species in this family (Sarcocystidae):
- Toxoplasma gondii, Neospora caninum, Hammondia hammondi, Besnoitia besnoiti
Thus, for species identification PCR is needed.
Post mortem: histological findings from intestinal mucosa.
Image left: unsporulated oocysts, right: sporulated oocyst.
Family Sarcocystidae consist of?
cyst-forming parasites
Cystoisospora, Sarcocystis, Toxoplasma, Neospora, Hammondia, Besnoitia
They cause sarcocystiosis.
Characterize Sarcocystis spp. life cycle.
Heteroxenous life cycle
Carnivores as definitive host.
Herbivores as intermediate host in which formation of cysts.
Size of the cysts vary from microscopic to macroscopic.
Describe Sarcocystis spp. & sarcocystiosis in general.
Very prevalent worldwide.
Excreted sporocysts are instantly infectious and survive for months to years.
Fecal stage sporocysts can survive sewage treatment without damage.
No cross-immunity between species.
ZOONOTIC Humans can be final host and accidental intermediate host!
Describe Sarcocystis spp. life cycle
Letters correspond to image.
A: Intermediate host ingests oocysts/sporocysts. Sporozoites released.
B: Sporozoites invade small endothelial cells in arterioles - asexual division. Many generations. After, merozoites released.
C: In striated muscles, heart muscles; merozoites turn into bradyzoites inside sarcocysts.
C1: Final host ingests tissues with sarcocysts.
D: Bradyzoites are released in small intestine.
E: Bradyzoites infect epithelial cells - sexual
replication - formation of oocysts.
G: Oocysts/ sporocysts shed in feces.
Shedding occurs for several months.
Duration: prepatent period is 8–33 days in dogs and 10–14 days in cat
Diagnosis of sarcocystiosis in herbivores.
During routine meat inspection in slaughterhouses you may find large cysts (whitish streaks running muscle fibre direction).
Clinical symptoms when infection is acute.
Histology/biopsy from kidneys and heart muscle - meronts may be found in capillaries.
Serological testing: presence of antibodies might not show an active infection.
Blood samples: lymphocytosis, anemia, low albumin, lactate dehydrogenase, AST increased, bilirubin increased.
