Protozoa Flashcards
Protozoa have typically been classified as _____
parasites
what is a parasite
an organism that lives on or within another organism and benefits from the association while harming its host
what are the types of parasites
-protozoa= single celled eukaryotes
- helminths = multicellular animals (worms) (eukaryotes)
what are the modes of transmission for protozoa
- vector - living transmitter of disease, most often arthropods
- resevoir - sources of parasites in environment not active transmitters of disease
how does the parasite grow/ replicate
intracellular or extracellular
describe protozoa
- diverse group of eukaryotic microbes
- related by their simple organization: unicellular or multicellular without specalized tissues
- most are free living in aquatic environments or on decaying organic matter
- some are parasitic
what is encystation
formation of a cyst
- resting state with a wall and low metabolic activity
what is the function of cysts
- protection from changes in environment
- sites for nuclear reorganization and cell division
- transfer from one host to another
what is excystation
escape of vegetative form from cyst
what is excystation triggered by
return to favorable environment
what is a trophozoite
-vegetative form released by parasitic species
- excystation often triggered by entry into new host
are all protozoa motile
no
motile species use one of the following:
- cilia
- flagella
- pseudopodia
what are the means of reproduction for protozoa
- asexual: binary fission- mitosis -> cytokinesis
- sexual : conjugation- exchange of gametic nuclei between paired protozoa of opposite mating types
what types of protozoa are zooflagellates
- giardia lamblia
- trichomonas vaginalis
- trypanosomes
what does giardia lamblia cause
giardiasis- gastro intestinal disorder
what does trichomonas vaginalis cause
sexually transmitted disease
what are trypanosomes
-hemoflagellates
- important blood pathogens
what is the most common cuase of epidemic waterborne diarrhea
giardiasis
what is the mechanism of action of giardiasis
-forms cysts and trophozoites
- trophozoites attach to intestinal epithelium and interfere with nutrient absorption
what is the transmission of giardiasis
- cyst contaminated water
- animal resevoirs
- asymptomatic human carriers
what are the clinical manifestations of giardiasis
-acute giardiasis- severe diarrhea, epigastric pain, cramps, voluminous flatulence, and anorexia
- chronic gastritis- intermittent diarrhea with periodic appearance and remission of symptoms
what is the treatment prevention and control of giardiasis
- antiprotozoal agents- metronidazole
- avoid contaminated water of purify first
what is the prevalence of trichomonas vaginalis
15% of women have it
is there a cyst stage in trichomonas vaginalis
no only trophozoites
what are the clinical manifestations of trichomonas vaginalis
- accumulation of leukocytes at site of infection
- in females- yellow purulent vaginal discharge and itching
- in males usually asymptomatic or burning urination
what is the treatment prevention and control of trichomonas vaginalis
- observation of parasite in vaginal discharge, semen or urine
- antiparasite therapy- metrodiazole
where is trichomonas tenax found and what is it associated with
in the mouth
- associated with poor oral hygiene
what are hemoflagellate diseases caused by
flagellated protozoa
what are the two major groups of flagellated protozoa
-leishmanias
- trypanosomes