Parasitology Exam 1 Flashcards
1
Q
Symbiosis
A
Any close/long term interaction between two organisms of different species
2
Q
Commensalism
A
one organism benefits and the other is neither benefitted nor harmed
3
Q
Mutualism
A
All species involved benefit
4
Q
Parasitism
A
Parasite dependent on host and benefits, while host harms
5
Q
What are the 3 main classes of parasites that can cause disease in humans?
A
Protozoa
Helminths
Ectoparasites
6
Q
What is the Domain of parasites?
A
Eukaryotes
7
Q
What are the 2 kingdoms of parasites?
A
Protista and Animalia
8
Q
What is the subkingdom of Protista?
A
Protozoa
9
Q
Protozoa: unicellular or multicellular
A
unicellular
10
Q
What is the subkingdom of Animalia?
A
Metazoa
11
Q
Are metazoa multicellular or unicellular?
A
Multicellular
12
Q
What phylums are in the subkingdom protozoa?
A
Mastigophora (flagellates)
Sarcodina (amoebae)
Ciliophora (ciliates)
Sporozoa
13
Q
What phylums are in the subkingdom metazoa?
A
Platyhelminthes (flat worms)
Nemathelminthes (round worms)
14
Q
Platyhelminths = ______ worms? What classes does platyhelminth include?
A
Flat worms
Cestoda (tape worms)
Trematoda (flukes)
15
Q
Trematoda
A
Flukes
16
Q
Cestoda
A
Tape worms
17
Q
Platyhelminths
A
Flatworms (flues and tapeworms)
18
Q
Nemathelminthes
A
Round worms
19
Q
What class is included in the phylum nemathelminthes?
A
Nematoda (round worms)
20
Q
Protozoa vs metazoa
A
protozoa: unicellular, able to multiply in humans, binary fission
metazoa: multicellular, cannot multiply in humans in adult form, sexual reproduction
21
Q
Platyhelminths vs nemathelminthes?
A
Platyhelminth = flat worm
Nemathelminthe = round worm
22
Q
Key characteristics of protozoa
A
- Unicellular
- Able to multiply in humans
- Can be intestinal or infect blood/tissue
- Reproduce asexually (binary fission)
23
Q
Key characteristics of Helminths
A
- Multicellular
- Cannot multiply in humans in their adult form
- Sexual reproduction
24
Q
Key characteristics of ectoparasites
A
- Arthropods that establish on the body surface of the host
- Can have 4 or 3 pairs of appendages (Arachnida and Insecta, respectively)
25
Which type of host shelters an organism which does not usually parasitize that host, not allowing transmission to the definitive host?
Accidental host
26
Which type of host is where sexual reproduction of a parasite takes place, and the host that harbors the adult parasite?
Definitive host
27
Which type of host is in which a parasite develops but does not reach sexual maturity, and the host that harbors asexual forms of the parasite?
Intermediate host
28
Which type of host harbors the parasite but produces no symptoms, and serves as a source of infection for humans?
Reservoir host
29
Which type of host is a carrier in which the organism remains alive, but does not develop or multiply, and is not necessary for the parasite's development cycle?
Transport (paratenic) host
30
What is an organism that does not cause disease itself, but carries and usually transmits parasites and diseases from one host to another, usually an arthropod, and is **essential for the completion of the life cycle**?
Vector
31
Diagnostic stage of a parasitic infection
Developmental stage of a pathogenic organism that can be detected in human specimens
32
Infective stage of a parasite
Stage where the parasite is capable of entering and continuing development within the host, required part of the life cycle for that parasite
33
Facultative parasite
Organism that may survive in the absence of a host but occasionally infects a host organism
34
Obligate parasite
Organism that cannot complete its life cycle without a host, cannot survive without a host
35
Overall, which populations are more affected by parasitic infections?
Poor and underdeveloped countries in tropical/subtropical regions (warm climates)
36
What are the WHO's top 5 most harmful parasitic diseases?
Malaria
Leishmaniasis
Trypanosomiasis
Onchocerciasis
Schistosomiasis
37
What safety precautions should be followed when handling parasitology specimens?
Biosafety Level 2
Proper PPE, biological safety cabinets, decontaminate, proper disposal, etc
38
How should stool specimens be preserved?
10% formalin and PVA (1:3 ratio of stool to preservative)
39
When can fresh stool samples be examined?
Immediately
40
When should stool samples be preserved? What ratio of stool to preservative?
ASAP; 1 volume of stool to 3 volumes of preservative
41
If stools are a type 7 (LIQUID) what would you see more of: trophs or cysts?
Trophs
42
If stools are a type 1 (SOLID) what would you see more of: trophs or cysts?
Cysts
43
Bristol stool chart type 1 vs type 7
type 1: solid
type 7: liquid
44
What are the two main preservatives for stool?
PVA and 10% formalin
45
What is the collection procedure for a parasitology stool specimen?
3 specimens passed at intervals of 2-3 days should be examined (3 specimens over 10 days)
46
How long do you have to examine liquid fresh stool specimens? (no preservative)
Within 30 minutes of passage
47
How long do you have to examine soft fresh stool specimens? (no preservative)
Within 1 hour of passage
48
How long do you have to examine formed fresh stool specimens? (no preservative)
Up to one day (24 hours) with overnight refrigeration
49
What does a fresh specimen permit? (what is a benefit)
Permits observation of motile trophozoites but must be carried out without delay
50
What is the purpose of concentration procedures for stool specimens?
Separates parasites from fecal debris to increase chances of detecting parasitic organism
51
What is the flotation technique?
A concentration method that uses solutions with higher specific gravity than organism, so organism floats to the top
52
What is the sedimentation technique?
A concentration method that uses solutions with lower specific gravity than organism, so organism settles to the bottom
53
Example of flotation technique
Zinc sulfate and Sheather's sugar
54
Example of sedimentation technique
Formalin-ethyl acetate technique
55
What specimens, preserved in 10% formalin, can a wet mount be performed on?
Protozoa and helminths
56
What specimens, preserved in 10% formalin, can an ELISA be performed on?
Giardia and cryptosporidium
57
What specimens, preserved in 10% formalin, can a chromotrope stain be performed on?
Microsporidia
58
What specimens, preserved in PVA, can the trichrome stain be performed on?
Protozoa
59
What preservative is required for the trichrome stain?
PVA
60
What preservative allows you to perform the sedimentation technique (formalin-ethyl acetate) on various organisms for more specific tests?
10% Formalin
61
What organisms can be safranin stained to test?
Cyclospora
62
What organisms can you perform a DFA on?
Giardia and cryptosporidum
63
What organisms can you perform an acid fast stain on?
Cryptosporidum and cyclospora, and isospora
64
What additional tests does the formalin-ethyl acetate concentration allow you to perform?
DFA, safranin stain, direct mount, acid fast stain, wet mount
65
T/F: blood specimens should be collected after treatment is initiated
False (before)
66
Why are multiple smears required for parasitic blood specimens?
Parasitemia may fluctuate for babesia and malaria
67
What type of parasite has marked periodicity depending on the species?
Microfiliariae
68
What is the purpose of the chromotrope stain, and what type of preservative is used?
Differentiate microsporidia spores
10% formalin
69
What is the purpose of the modified acid-fast stain, and what preservative is used?
ID oocyts of cyclospora, cryptosporidium, cystoisospora (fresh or formalin-preserved)
70
What is the purpose of the safranin stain and what preservative is used
ID oocysts of cyclospora, cryptosporidium, cystoisospora
Fresh or formalin-preserved
71
What is the purpose of the trichrome stain and what preservative is used
ID of cysts and trophozoites of intestinal protozoa
Fresh stool or PVA
72
What are the rules of blood parasite collection?
- 2 thick and 2 thin smears must be made
- Must make smears within 1 hour of collection of EDTA specimen
73
What does a thick smear allow for? What does it not allow for?
More efficient detection of parasites - quicker to tell if they are present or not because it is more concentrated
Does not allow for species ID
74
What does a thin smear allow for?
Allows for parasite ID and detection
75
How is a thin smear made vs a thick smear?
Thin smear: Wright-Giemsa stain on Midas like normal
Thick smear: 1 ml of Giemsa stain to 50 mL of XPR plus Buffer (AlphaTec) - stain for 45 min and must air dry for a long time (can not use heated drying rack)
76
How does a thin smear look different than a thick smear under the microscope?
Thin smear will look like a normal blood smear, can see individual RBC
Thick smear will not be able to see RBCs, just organisms if they are present
77
When is a stereoscopic microscope used for parasitic examination?
Recommended for larger specimens (arthropods, tapeworms)
78
What is the purpose of a stage (ocular) micrometer?
Must be used for final ID, allows microbiologist to determine the exact size of the parasitic element
79
When is a brightfield microscope used in parasitic exam?
Always used first
80
What is the gold standard to ID parasites?
Microscopic examination
81
What is the purpose of using a wet mount for stool specimens?
ID of protozoan trophozoites, cysts, oocysts, and helminth eggs and larvae
82
What is the purpose of using stained slides for stool specimens?
ID of protozoan trophozoites and cysts and for confirmation of species
83
What is the purpose of using UV fluorescence for stool specimens?
Enhanced demonstration of Cyclospora oocysts
84
Procedure for examining stool specimen stained slides
Must examine 200-300 fields at 100x
85
Procedure of wet mount examination of stool specimen
- Two smears prepared on one slide, one stained with iodine
- Place coverslip over each smear
- Thickness should be able to read newsprint through specimen
- Scan entire coverslip area at 10x, if anything suspicious use a higher magnification
86
What will Cyclospora oocysts look like under UV fluorescence microscopy?
Blue circles
87
List 3 microscopic tests that can be performed on a stool specimen
Wet mount
Stained slide
UV fluorescence
88
What do you result if you dont see any parasites on a blood smear?
NPF (No parasites found)
89
Allowed specimens for parasititic blood tests
- Whole blood w/ no anticoagulant
- Anticoagulated whole blood
- Sediment from concentration procedures
90
Two most commonly used stains for blood specimens
Wright's and Giemsa
91
Blood film for parasitic exam is always _______.
STAT
92
Rules for examination of thin/thick blood smears
2 of each made
Minimum of 300 fields on BOTH must be examined before reported smear as NPF
93
What do you do when you see a parasite on a thin blood smear?
Identify parasite species and determine % parasitemia if relevant
94
What do you do when you see a parasite on a thick blood smear?
Make a tentative species determination, move to thin smear to quantify and ID
95
When would you determine % parasitemia after seeing parasites on a blood film? (which organisms)
Only intracellular parasites (Malaria and babesia)
96
Formula for % parasitemia
(Parasitized RBCs/total RBCs counted) x 100
97
Procedure for determining % parasitemia
Count parasitized RBCs among 500-2000 RBCs on thin smear, divide parasitized by total counted to get percentage
98
T/F: If multiple parasites are seen in a single cell, that cell is only counted as one parasitized cell.
TRUE
99
Which preservatives are good for molecular testing?
TotalFix
Unifix
Modified PVA
Ecofix
100
Which preservatives are bad for molecular testing?
10% Formalin
SAF
LV-PVA
Protofix
101
Why are parasitic molecular testing specimens ALWAYS accompanied by blood smears?
PCR testing will NOT be performed if ID can be determined by microscopic exam (microscopic exam is gold standard and cheaper)
102
What blood parasites are RDTs/EIAs available for?
Plasmodium and Wuchereria bancrofti
103
What stool parasites are RDTs/EIAs available for?
Cryptosporidium sp, Giardia duodenalis, Entamoeba histolytica/dispar
104
Why isn't antibody testing (serum/plasma) commonly used to diagnose parasitic infections?
Cannot tell if patient currently is infected or has been infected in the past
105
What organism is the cellophane tape preparation used for? What are the rules for collection?
Pinworm (Enterobius vermicularis) - recovery of eggs
- Must use clear tape, must be performed at night/early morning (preferably when child is still asleep)
106
Non-blood/stool specimens that may be sent for parasitic testing? What organisms found with each?
Duodenal drainage - G. duodenalis or S. stercoralis
Urogenital tract specimens - T. vaginalis
Sputum - organisms that may cause pneumonia, pneumonitis, or Loeffler syndrome
Bone marrow/CSF/Cyst aspirates - hydatid disease, leishmania, trypanosoma cruzi, plasmodium, naegleria fowleri
Biopsy - tissue specimens
107
Why might parasitic culture techniques be used?
Diagnostic testing methods, epidemiologic analysis of outbreaks, testing drug resistance, life cycle analysis
108
Detection of what organism are corneal scrapings or contact lenses inoculated onto agar overlayed with E. coli or Enterobacter?
Acanthamoeba
109
What is an axenic culture technique?
Parasite grown in PURE culture without augmentation with bacteria
110
What is a monoxenic culture technique?
A single known bacteria species used to help cultivate the parasite
111
What is a coproculture technique?
Fecal culture methods useful for detection of hookworm, S. stercoralis, and Trichostongylus infections
112
What is xenodiagnosis?
Use of an intermediate host to isolate a parasitic organism from a human host (ex. T. cruzi)
113
Preventative measures for parasitic infections
: Improved personal hygiene
: Ensure proper sanitation
: Avoid fecal-oral contact
: Avoid contaminated water or
soil
114
Ectoparasites
Members of the phylum arthropoda that act as biological and mechanical vectors
115
ID of ectoparasites is based on?
Recognizing morphological characteristics
116
4 characteristics of arthropods
- Chitinized exoskeleton
- Pairs of jointed legs or appendages
- Bilateral symmertry
- Hemocele (contain blood or lymph)
117
Arachnida vs Insecta
Arachnida: 4 pairs of appendages
Insecta - 3 pairs of appendages
118
What are chemoprophylactic agents?
Given to individuals traveling to areas where malaria is endemic
