protozoa parasites Flashcards
what are protozoa
the term no longer carries specific taxanomic value but is used informally to describe a diverse range of unicellular eukaryotes belonging to a number of unrelated phyla
greek= first animals
outline some characteristics of protozoa
1) wide range of morphologies e.g. amobeboid, spherical or spindle shape
2) large range of sizes from less than 1um to several mm
3) some cells have cilia others have flagella
4) some are naked others have some sort of cell wall or shell
what are different methods and tools used to identify protozoa
1) microscope and special dyes
2) electron microscope needed for more detailed morphological studies
3) ELISA- looks for antigens or proteins which react to an antibody against it- used more in research than applied settings
4) molecular probes
why are numbers when it comes to parasites such as infection rates or number of species so inaccurate
depends on the demographic looked at
individuals which have access to health centres more likley to be recorded and cured vs those who just live with it
what is meant by a zoonotic species or parasite
infects humans and animals
outline a protozoans life cycle
1) exhibit different morphologies which could lead to mistaken as different species
2) asexual reproduction common
3) all life processes at unicellular level so more complex than seen in cells of multicellular organisms
what are the two life stages seen in alot of protozoa
1) cyst= round/oval, no flagella, 11-14um
- the metabollically inactive stage which usually allows survival in harsh conditions outside the host
2) trophozoites= active feeding/reproducing stage usually inside the host
what are the different feeding mechanisms of protozoans
1) osmotrophy - absorb solutes from their media
2) phagotrophy- ingest solid material
3) autotrophy- photosynthetic capture solar energy
4) predatory- feed on other organisms
5) heterotrophic- utilise many combinations as above
what are some mechanisms of movement for protozoa
1) amoeboid movement
2) flagella
3) cilia
4) gliding mobility aka sailing
what are some protozoa parasites in the phylum sarcomastigophora
1) entamoeba
2) Giardia, Trichomonas
3) Trypanosoma, Leishmania
outline some characteristics of amoeba
- present in human and primate digestive systems
- world wide distribution
- they cause histolysis (disintegration of organic tissues)
what are some symptoms of an amobea paraiste
- bloody diarrhoea from shedding of small intestine lining to rid of parasite
- weight loss
- fatique
- abdominal pain
- lesions/ulcers on intestine
how do amoebas live in a host
bore into the intestinal wall causing lesions and sometimes reach the blood stream, usually through the hepatic duct allow travel to liver lungs and brain
- third leading cause of morbidity (ill health) and mortality due to parasitic disease in humans
how are amobeas a facultative pathogen
they require more than one environment for it to cause illness
outline the parasite E.histolytica trophozoite morphology
1) two forms- cysts and trophozoite
2) 10-60um
3) normally feeds on bacteria and debris in large intestine
4) can enter vascualr system and invade organs
5) lack golgi body and mitochondria
6) single nucleus
outline the E.histolytica cyst morphology
1) 12-16um
2) hyaline wall 0.5um thick (cell wall)
3) increases number of nuclei as it matures
4) non feeding
outline the lifecyle of E.histolytica
1) host ingests contaminated food containing cysts
2) cysts pass through stomach into ileum where they excyst into trophozoites
3) colonise colon, small intestine and rectum
4) binary fission produces more
5) when exposed to harsh conditons outside host encystation ours forming cysts for cycle to repeat
outline the process of excystation
- cyst wall disrupts
- amoeba emerges
- nuclear division 4-8
- cytoplasmic divsion forming 8 trophozoites from one cyst
outline the process of encystation
1) trophozoite rounds up
2) secretion of hyaline cyst wall
3) aggregation fo ribosomes
4) two rounds of nucelar division 1-4 nuclei
outline characteristics of parasite Giardia lamblia
- world wide distribution
- high numbers in underdeveloped countries
- common in stools
- good example to show correlation between parasitism and economy
what are some symptoms of Giardia lamblia
1) often asymptomatic but acute symptoms
- watery diarrhea, bulky, frothy, greasy and foul smelling, no blood or mucus
- upper gastro-intestinal unease, bloating, vomiting
outline morphology of Giardia lamblia trophozoites
1) large adhesive disc on ventral anterior half
2) 2 nuclei containing a karyosome
3) 2 median bodies containing microtubules
4) axoneme
5) 8 flagella
- looks like a smiley face
outline the morphology of Giardia lamblia cyst
- oval shaped
11-14 um
distinct cell wall
4 nuceli at anterior end
axonemes
median bodies
outline lifecycle
1) excystation in stomach when exposed to acidic PH then to neutral PH
2) encystation when in small intestine
- has many zoonotic hosts which make it very common
outline characteristics of the parasite Trichomonas vaginalis
- only found in humans
- only sexually transmitted parasite of humans
- should be easy to control but can be asymptomatic for years
- 7-23um length
- 4 anterior flagell
- slender axostyle which is its ID feature
what is an axostyle
used to attach to surfaces
may cause the tissue damage noted in infection
outline morphology of Trichomonas vaginalis
1) obtain nutirents by transport through cell membranes and phagocytosis
2) lack mitochondira and other enzymes to conduct oxidative phosphorylation
instead enegry generated by hydrogen some
outline lifecyle of Trichomonas vaginalis
1) resides in female lower genital tract and male urethra and prostate
2) replicates by binary fission
3) feed on bacteria on mucosal surface by phagocytosis
4) cant survive outside host
5) transmited by discharge of body fluids
has no cyst stage only trophozoite stage
how is Trichomonaqs vaginalis diagnosed and treated
1) rapid but insensitive method- microscopic examination but depnds on ability to see ID features
2) more sensative but complex method- immunoflorescent antibody staining = takes longer
treatment= antibiotics such as metronidazole, use of condom
