protozoan parasites with direct life cycles Flashcards
what are protozoa?
-single celled organisms
-very small organisms measured in microns
-eukaryotes
-unknown until the invention of the microscope in 1675
what are the examples of disease caused by parasitic protozoa
-amoebic dysentry
-malaria
-sleeping sickness and animal trypanosomiasis
-tick borne diseases of livestock
-toxoplasmosis
-coccidiosis
what are the four phyla of parasitic protozoa?
-phylum apicomplexa
-phylum euglenozoa
-phylum ciliophora
-phylum amoebozoa
Treating protozoal disease and preventing protozoal infection is…
expensive
what is phylum ampicomplexas?
ampicomplexans move by body flexion, all are parasitic, using the apical complex to invade host cells
what is phylum euglenozoa?
flagellates move by one or more whip like processes or flagella
what is phylum ciliospore?
ciliates move by short hair like processes or cilia
what is phylum amoeboxoa
amoebae move by processes or pseudopodia
what are some diseases that are coccidia
-eimeria
-toxoplasma
-neospora
-cryptosporidium
-isospora
-sarcocystitis
what are some diseases that are piroplasms
-babesia
-theileria
what are some diseases that are ciliates
balantidium
rumen
ciliates
what are some diseases that are flagellates
-leishmania
-trichomonas
-trypanosoma
-giardia
-histomonas
what is a definitive host?
One in which a parasite reaches maturity and usually reproduces sexually
what is an intermediate host?
One in which the parasite develops, but does not reach maturity or reproduce sexually
what is a vector?
Intermediate host that carries adn transmits parasite developmental stages to another host
what is a direct life cycle?
Only definitive host require
what is an indirect life cycle?
Requires definitive and intermediate hosts
what is a vector-borne life cycle?
Requires definitive host and intermediate host vector
what are enteric pathogens?
Direct and indirect life cycles
Water borne or soil transmitted
what are haemoparasites?
-Indirect life cycles
-Vector borne-Transmission by mosquitos, tsetse fly, sticks
-Causes fevers, anaemia and worse
what are systemic pathogens?
Like Enteric and haemoparasites but more serious
what are the basic forms of coccidial parasites?
-trophozoite
-gametes
-oocyst
what is the structure of apical complex?
-rhoptries
-micronemes
-polar rings
-conoid
what is the function of apical complexes?
-enable parasite to penetrate host cells
-activated by the release of sequestered calcium ions into the parasite cytoplasm
how do ampicoplexa enter the host cell?
- receptor detects host cell
- reorientation
- parasite inside vacuole
- parasitophorous vacuole forming
what is special about the way ampicoplexa multiply?
-multiply sexually within host by schizogony
-multiple nuclear division precedes cytoplasmic division
what are the stages of the eimeria species direct life cycle?
- Only definitive host is necessary for its completion
- One phase in host and one in environment
- Host becomes infected by ingesting sporulated oocysts fmro environment such as food or bedding
- Sporozoites are released into gut epithelial cells where under go one or more asexual cycles of schizogony
- Go onto invade further gut epithelial cells and can also form macrogametes or microgames here
- Microgametes fertilise macrogametes to produce oocysts which are released into the gut lumen and voided in the faeces into the environment
- Oocysts can survive for months in the environment but must undergo maturation/sporulation to form sporocysts and sporozoites which are infectious once ingested
what are the environmental conditions affecting coccidia and disease?
-temperature
-humidity
-hygiene
what are the host factors affecting coccidia and disease?
-age- young
-immunity- naive
-density- intensification
what is the pathology caused by Eimeria tenella?
-thickening of mucosa, inflammation, haemorrhage and necorsis
-eimeria tenella has a predilection for the caeca: useful for diagnosis
Name a Coccidian species which affects Chickens?
E. tenella
E. praecox
Name a Coccidian species which affects Cattle?
E. bovis
Name a Coccidian species which affects Sheep and goats?
E. ovanoidallis
Name a Coccidian species which affects pigs
cystoisospora suis
Name a Coccidian species which affects dogs?
cystoisospora canis
Name a Coccidian species which affects cats?
cystoisospora felis
Name a Coccidian species which affects Rabbits
E. intestinalis
E. flavescens
what are the infective stages of eimeria?
-unsporulated oocyst requires warmth, moisture and oxygen to sporulate
-forms sporulated cyst which can resist disinfection and persist in environment
what are the infective stages of eimeria?
-unsporulated oocyst requires warmth, moisture and oxygen to sporulate
-forms sporulated cyst which can resist disinfection and persist in environment
what is cryptosporiuim parvum?
-A very tin cocidian parasite
-Pathogen of domestic animals and humans
-Disease: cryptosporidiosis
-Common zoonosis
Clinical signs= Intermittent anorexia and diarrhoea
-No treatment (Self limiting)
what happens in autoinfection?
may sporelate before leaving infection and release sporozoites that infect same individual
Where is cryptosporidium schizonts located?
-located within brush border
where does cryptosporidium schizonts develop?
space between cytoplasm and cell membrane
what are some other features of cryptosporidium schizonts?
-intracellular but extracytoplasmic location
-infected microvilli are destroyed when the parasite leaves the cells
how big are cryoptosporidium oocysts and what are they resistant to?
3-5um in diameter
Chlorination
is autoinfection possible in cryoptosporidium oocysts?
yes- sporozoites released from oocysts within the intestine may re-infect same individual
what are giardia lamlia?
-causes diarrhoea in many birds and mammals e.g. dogs and humans
-zoonosis
-trophozoites attach with suckers to epithelial cells of the small intestine
-the very distinctive trophozoites can sometimes be found in the faeces
what are tritrichomonas feoeus features?
-simple direct life cycle
-sexual transmission
what are the tritrichomonas feoeus features in the bull and the cow
Bull is asymptomatic
Cow has…
-infertility
-abortion
-embryonic and early fetal death
-fetal maceration
-pyometra
-vaginal discharge
what are the tritrichomonas feoeus features in cats?
typhlocolitis
what are the features of spironucleus meleagridis?
-small <10um
-catarrhal enteritis in turkey poults and game birds
-adult birds are asymptomatic carriers
-transmission by faeco-oral route of encysted
what are is the presentation of histomonas meleagridis?
‘blackhead’ in turkeys and chickens
what does histomonas meleagridis cause?
-necrotic lesions in the caecum
-focal necrosis in liver
-cyanosis of head and wattle due to poor blood supply
how does histomonas meleagridis migrate?
in portal circulation
what is the indirect life cycle of histomonas meleagridis?
-heterakis gallinarium
-found in caecum
-histomonas invades nematode
-histomonas within heterakis eggs
what can ingest heterakis eggs?
-birds OR
-ingested by and develop within earthworm
-bird eats earworm containing heterakis containing histomonas
-becomes infected with both parasites simultaneously
what is histomonas meleagridis found in?
free range turkeys and chickens
