Protozoa Flashcards
1
Q
Protozoa have typically been classified as _____
A
parasites
2
Q
what is a parasite
A
an organism that lives on or within another organism and benefits from the association while harming its host
3
Q
what are the types of parasites
A
-protozoa= single celled eukaryotes
- helminths = multicellular animals (worms) (eukaryotes)
4
Q
what are the modes of transmission for protozoa
A
- vector - living transmitter of disease, most often arthropods
- resevoir - sources of parasites in environment not active transmitters of disease
5
Q
how does the parasite grow/ replicate
A
intracellular or extracellular
6
Q
describe protozoa
A
- 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
7
Q
what is encystation
A
formation of a cyst
- resting state with a wall and low metabolic activity
8
Q
what is the function of cysts
A
- protection from changes in environment
- sites for nuclear reorganization and cell division
- transfer from one host to another
9
Q
what is excystation
A
escape of vegetative form from cyst
10
Q
what is excystation triggered by
A
return to favorable environment
11
Q
what is a trophozoite
A
-vegetative form released by parasitic species
- excystation often triggered by entry into new host
12
Q
are all protozoa motile
A
no
13
Q
motile species use one of the following:
A
- cilia
- flagella
- pseudopodia
14
Q
what are the means of reproduction for protozoa
A
- asexual: binary fission- mitosis -> cytokinesis
- sexual : conjugation- exchange of gametic nuclei between paired protozoa of opposite mating types
15
Q
what types of protozoa are zooflagellates
A
- giardia lamblia
- trichomonas vaginalis
- trypanosomes
16
Q
what does giardia lamblia cause
A
giardiasis- gastro intestinal disorder
17
Q
what does trichomonas vaginalis cause
A
sexually transmitted disease
18
Q
what are trypanosomes
A
-hemoflagellates
- important blood pathogens
19
Q
what is the most common cuase of epidemic waterborne diarrhea
A
giardiasis
20
Q
what is the mechanism of action of giardiasis
A
-forms cysts and trophozoites
- trophozoites attach to intestinal epithelium and interfere with nutrient absorption
21
Q
what is the transmission of giardiasis
A
- cyst contaminated water
- animal resevoirs
- asymptomatic human carriers
22
Q
what are the clinical manifestations of giardiasis
A
-acute giardiasis- severe diarrhea, epigastric pain, cramps, voluminous flatulence, and anorexia
- chronic gastritis- intermittent diarrhea with periodic appearance and remission of symptoms
23
Q
what is the treatment prevention and control of giardiasis
A
- antiprotozoal agents- metronidazole
- avoid contaminated water of purify first
24
Q
what is the prevalence of trichomonas vaginalis
A
15% of women have it
25
is there a cyst stage in trichomonas vaginalis
no only trophozoites
26
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
27
what is the treatment prevention and control of trichomonas vaginalis
- observation of parasite in vaginal discharge, semen or urine
- antiparasite therapy- metrodiazole
28
where is trichomonas tenax found and what is it associated with
in the mouth
- associated with poor oral hygiene
29
what are hemoflagellate diseases caused by
flagellated protozoa
30
what are the two major groups of flagellated protozoa
-leishmanias
- trypanosomes
31
how are hemoflagellate diseases transmitted
by bites of infected arthropods
32
what is african trypanosomiasis
- african sleeping sickness
- chronic blood stream infection with bouts of parasitemia
- CNS invasion after months to years
33
how is african trpanosomiasis transmitted
by tsetse flies
- resevoirs are domestic cattle and wild animals
34
what are the clinical manifestations of african trypanosomiasis
- interstitial inflammation and necrosis within lymph nodes and small blood vessels of brain and heart, leading to lethargy and death within 1 to 3 years
35
how is african trypanosomiasis diagnosed
observation of motile parasites in the blood
36
when is drug therapy used for african trypanosomiasis
during systemic stage
37
why is vaccine not useful in african trypanosomiasis
antigenic variation
38
what is chagas disease
american trypanosomiasis
- most people affected in childhood
- early disease is mild
- small percentage develop complications 10-20 years later
39
what is chagas disease transmitted by
kissing bug
- resevoirs are domestic cattle and other animals
40
what complications are brought on by chagas disease
heart disease and other disorders due to destruction of parasitized cells in the liver, spleen, lymph nodes and CNS
- megaesophagus, megacolon
- cardiomyopathy
41
what are the treatments for chagas disease
no treatment available for late complications
- vaccines not useful because of antigenic variation
42
what is leishmaniasis transmitted by
- sand flies
- animal resevoirs are canines and rodents
43
where does leishmania survive and differentiate
macrophages
44
what are the 3 forms of leishmaniasis infection
mucocutaneous, cutaneous and visceral
45
what does the visceral form of leishmaniasis infection involve
- tissue macrophage disfunction
- intermittent fever and enlargement of spleen or liver
46
what does recovery of leshmaniasis provide
permanent immunity
47
describe the treatment, prevention and control of leishmaniasis
- amphotericin B
- vector and resevoir control and epidemiological surveillance
48
what is amoebiasis and what is it caused by
- amoebic dysentery
- caused by entamoeba histolytica
49
how is amoebiasis transmitted and what are the clinical symptoms
- ingestion of cysts
- asymptomatic to fulminationg dysentery, exhaustive diarrhea, and abscesses of liver, lungs and brain
50
what is the treatment, prevention and control of amoebiasis
- observatino of trophozoites in fresh warm stools or cysts in ordinary stools and serological tests
- metronidazole
- avoid contaminated water and food
51
describe phylum apicomplexa
- lack locomotor organelles
- all have apical complex: arrangement fibrils, tubules, vacuoles and other organelles at one end of cell
52
what is the apicomplexan life cycle
- involves two different hosts
- involves both asexual and sexual phases
53
what are the sexual and asexual phases of the apicomplexan life cycle
- schizogony is asexual phase: rapid series of mitotic events producing infective organisms
- oocyst is sexual phase: thick walled, diploid structure, undergoes meiosis to produce haploid spores
54
what are the important sporozoan genera
-plasmodium - malaria
- cryptosporidium - cryptosporidosis
- toxoplasma- toxoplasmosis
55
what is malaria caused by
- plasmodium falciparum
- plasmodium vivax
- plasmodium malariae
- plasmodium ovale
56
what is malaria transmitted by
bite of an infected female anopheles mosquito
57
what is the resevoir, intermediate host, and definitive host of malaria
reservoir: humans
intermediate host: humans asexual reproduction
-definitive host: mosquito sexual reproduction
58
what causes recurrent malaria
- P vivax and P ovale form hypnozoites within liver cells
59
what are the clinical manifestations of malaria
periodic attacks of chilld and fever
60
how is malaria diagnosed
demonstration of parasites within wright or Giemsa stained RBCs and seroligcal tests
61
how is malaria treated and prevented
- antimalarial drugs- chloroquine
- chemoprophylaxid for people travelling to endemic areas, netting, and insect repellants
62
where is babesia found and what is it transmitted by
- endemic to USA
- transmitted by same Ixodes tick as Borrelia burgorferi
63
what are the symptoms of babesia
subclinical to severe disease, summer flu
64
how does babesia infect
protozoa infect RBCs and cause fever upon damage
65
what is the resevoir for babesia
white footed mouse
66
how is babesia diagnosed and treated
- microscopy of Giemsa stained blood samples, PCR
- clindamycin and quinine
67
what is toxoplasmosis caused by and how is it transmitted
- toxoplasma gondii
- transmission of ingested and undercooked meat, congenital transfer, blood transfusion, tissue transplant and ingestion of cat feces
68
what is the most common form of transmission for toxoplasmosis
undercooked meat containing tissue cysts
69
what is the definitive host for toxoplasmosis
cat
70
how does toxoplasmosis infect
invades macrophages
71
what are the clinical manifestations of toxoplasmosis
- asymptomatic or resmebles mononucleosis
- can be fatal in immunocompromised hosts
- congenital infections
72
what is the treatment, prevention and control of toxoplasmosis
- antiparasite therapy for immunocompromised patients
- minimize exposure by avoiding raw meat and eggs
- women screened for antitoxoplasma antibody at marriage or very early in pregnancy
73
what is cryptosporidosis caused by
cryptosporidium parvum
-apicomplexan that forms cysts, sporozoites and merozoites
74
what is cryptosporidosis resistant to
chlorine
75
how is cryptosporidosis transmitted
-animal resevoirs and in contaminated food or water
- many birds and mammals shed oocysts in feces
- also spread person to person in crowded urban environments
- public water system risks
- swimming pools
76
what are the clinical manifestations of cryptosporidosis
- diarrhea, abdominal pain, nausea, fever and fatigue
- self limiting
- can be fatal in late stage AIDS patients and other immunocompromised individuals
77
what is the treatment of cryptosporidosis
- microscopic examination of stools
- symptomatic/ supportive therapy
