protozoa parasites

Question 1

what are protozoa

Answer 1

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

Question 2

outline some characteristics of protozoa

Answer 2

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

Question 3

what are different methods and tools used to identify protozoa

Answer 3

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

Question 4

why are numbers when it comes to parasites such as infection rates or number of species so inaccurate

Answer 4

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

Question 5

what is meant by a zoonotic species or parasite

Answer 5

infects humans and animals

Question 6

outline a protozoans life cycle

Answer 6

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

Question 7

what are the two life stages seen in alot of protozoa

Answer 7

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

Question 8

what are the different feeding mechanisms of protozoans

Answer 8

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

Question 9

what are some mechanisms of movement for protozoa

Answer 9

1) amoeboid movement
2) flagella
3) cilia
4) gliding mobility aka sailing

Question 10

what are some protozoa parasites in the phylum sarcomastigophora

Answer 10

1) entamoeba
2) Giardia, Trichomonas
3) Trypanosoma, Leishmania

Question 11

outline some characteristics of amoeba

Answer 11

• present in human and primate digestive systems
• world wide distribution
• they cause histolysis (disintegration of organic tissues)

Question 12

what are some symptoms of an amobea paraiste

Answer 12

• bloody diarrhoea from shedding of small intestine lining to rid of parasite
• weight loss
• fatique
• abdominal pain
• lesions/ulcers on intestine

Question 13

how do amoebas live in a host

Answer 13

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

Question 14

how are amobeas a facultative pathogen

Answer 14

they require more than one environment for it to cause illness

Question 15

outline the parasite E.histolytica trophozoite morphology

Answer 15

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

Question 16

outline the E.histolytica cyst morphology

Answer 16

1) 12-16um
2) hyaline wall 0.5um thick (cell wall)
3) increases number of nuclei as it matures
4) non feeding

Question 17

outline the lifecyle of E.histolytica

Answer 17

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

Question 18

outline the process of excystation

Answer 18

• cyst wall disrupts
• amoeba emerges
• nuclear division 4-8
• cytoplasmic divsion forming 8 trophozoites from one cyst

Question 19

outline the process of encystation

Answer 19

1) trophozoite rounds up
2) secretion of hyaline cyst wall
3) aggregation fo ribosomes
4) two rounds of nucelar division 1-4 nuclei

Question 20

outline characteristics of parasite Giardia lamblia

Answer 20

• world wide distribution
• high numbers in underdeveloped countries
• common in stools
• good example to show correlation between parasitism and economy

Question 21

what are some symptoms of Giardia lamblia

Answer 21

1) often asymptomatic but acute symptoms
- watery diarrhea, bulky, frothy, greasy and foul smelling, no blood or mucus
- upper gastro-intestinal unease, bloating, vomiting

Question 22

outline morphology of Giardia lamblia trophozoites

Answer 22

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

Question 23

outline the morphology of Giardia lamblia cyst

Answer 23

• oval shaped
  11-14 um
  distinct cell wall
  4 nuceli at anterior end
  axonemes
  median bodies

Question 24

outline lifecycle

Answer 24

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

Question 25

outline characteristics of the parasite Trichomonas vaginalis

Answer 25

• 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

Question 26

what is an axostyle

Answer 26

used to attach to surfaces
may cause the tissue damage noted in infection

Question 27

outline morphology of Trichomonas vaginalis

Answer 27

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

Question 28

outline lifecyle of Trichomonas vaginalis

Answer 28

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

Question 29

how is Trichomonaqs vaginalis diagnosed and treated

Answer 29

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