Parasites - Blood And Tissue Flashcards

1
Q

What are the 4 common parasites that blood is tested for?

A

Malaria
Trypanosomiasis
Filariasis
Toxoplasmosis

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2
Q

Describe the timing of the blood samples taken when testing for parasites

A

Specimen collected before treatment
8-12 hour intervals every 2-3 days

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3
Q

When should you take a blood sample when testing for W. Bancroftii

A

After 8pm

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4
Q

When should you take a blood sample when testing for Brugia spp (filiarisis)

A

At night after 8pm

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5
Q

When should you take a blood sample when testing for Mansonell sp (filiarisis)

A

Any time

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6
Q

When should you take a blood sample when testing for Loa Loa (filiarisis)

A

10am-2pm

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7
Q

What type of blood samples are used to detect parasites

A

Venous blood
Capillary blood

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8
Q

What are the conditions for taking a venous or capillary blood sample for parasite testing?

A

Vacuum Tube with anticoagulant
EDTA

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9
Q

List three procedures done to detect blood parasites

A

Direct examination of Blood
Blood smear
Concentration

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10
Q

When are blood smears used ?

A

To detect infection
(Smears must be fixed and stained to reveal organisms)

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11
Q

What method is used to reveal
Plasmodium species in the blood?

A

Thick and Thin Smear
Wright/Giemsa Stain

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12
Q

What method is used to reveal
Leishmania species in the blood?

A

Buffy coat
Giemsa Stain

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13
Q

What method is used to reveal
Trypanosoma species in the blood?

A

Buffy coat/ Giemsa stain

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14
Q

What method is used to reveal
Microfilariae species in the blood?

A

Concentration/ Giemsa Stain

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15
Q

What method is used to reveal
Toxoplasma gondii species in the blood?

A

Buffy coat/ Giemsa Stain

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16
Q

List one advantage of a thin smear

A
  • able to differentiate species
    Because the RBC is kept intact and the morphology of the organism is better seen
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17
Q

List one advantage of thick smear

A

Able to detect light (low parasite load) infections

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18
Q

List 3 disadvantages of Thick smears

A
  • RBCs are lysed so speciation cannot be done
  • more experience to recognize organisms
  • blood has to be dried overnight
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19
Q

List two disadvantages of detecting blood parasites with a thin blood smear

A
  • light infections are harder to detect
  • more time consuming
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20
Q

What are the four main types of Malaria

A

Plasmodium falciparum
Plasmodium Vivax
Plasmodium Malriae
Plasmodium Ovale

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21
Q

Describe the size of the RBCs in each specie of malaria

A

Plasmodium falciparum - normal
Plasmodium Vivax - enlarged
Plasmodium Malriae - normal
Plasmodium Ovale - enlarged

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22
Q

Describe the morphology of an RBC infected with P. Falciparum

A
  • normal cell size
  • multiple signet rings
  • rings on the periphery on the cell
  • 2 chromatid dots on the signet rings
  • banana shaped gametocyte
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23
Q

Describe the morphology of an RBC infected with P. Vivax

A
  • enlarged rbc
  • single signet ring
  • schuffner’s dots in cytoplasm
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24
Q

Describe the morphology of an RBC infected with P. Malariae

A
  • single signet ring (thicker than others)
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25
Describe the morphology of an RBC infected with P. Ovale
- Enlarged - Single signet ring - oval shape - large (but single) chromatid dot - schuffner’s dots
26
Trypanosoma app causes which disease
Chagas Disease (tripanosomiasis)
27
List two species of trypanosomiasis and describe their morphology under the microscope
Trypanosomiasis cruzi: c,s,u shape , with large kinetoplast, does not multiple in peripheral blood Trypanosomiasis Brucei: squiggly, with small kinetoplast, multiples in peripheral blood
28
What is the vector of Trypanosoma cruzi
Kissing bug/ Triatominae
29
What is the vector of Trypanosoma brucei?
Cattle Fly/ Tsetse
30
Which specie of Trypanosoma is endemic to the Americas
Trypanosoma Cruzi
31
Which specie of Trypanosoma is endemic to the Africa
Trypanosoma Brucei
32
Which countries is the plasmodium falciparum species of malaria commonly found?
Jamaica Haiti Venezuela Suriname Guyana South Africa
33
Which countries is the plasmodium vivax species of malaria commonly found?
Jamaica, Haiti, Guyana, Suriname, Venezuela, South Africa
34
Which countries is the plasmodium malariae species of malaria commonly found?
Jamaica Haiti
35
Which countries is the plasmodium malariae species of malaria commonly found?
Jamaica Haiti
36
Which countries is the plasmodium ovale species of malaria commonly found?
Columbia Venezuela
37
List 5 reasons plasmodium falciparum is the most severe
1.Cerebral malaria 2.Infects RBCs of all ages 3.Intravascualr haemolysis 4.Drug resistance 5.acute renal failure 6.adult respiratory distress syndrome
38
List the steps to prepare a thick film for malaria testing
1.Prepare at least 2 smears per patient! 2.Place a small drop of blood in the center of the labeled slide 3.Using the corner of another slide spread the drop in a circular pattern until it is the size of a dime (1.5 cm2). 4.If placed (wet) over newsprint you shoul be to barely able to read the words 5.Allow the smears to dry 6.Lyse RBCs in buffer 7.Stain using Wright’s Giemsa
39
List the steps to prepare a thin film for malaria testing
1.Place a small drop of blood on slide 2.Bring another slide at a 30-45° angle up to the drop, allowing the drop to spread along the contact line of the 2 slides. 3.Quickly push the upper (spreader) slide forward on the lower slide. 4.Allow the thin smears to dry 5.Fix the smears by dipping them in absolute methanol 6.Stain using Wright’s Giemsa
40
Which mosquito transmits malaria?
Female Anopheles
41
How is W. Bancrofti detected
Microfilariae detected in peripheral blood Antigen detected with EIA (enzyme immunoassay) Antibody detection (chronic cases)
42
What WHO criteria must be met before a thick smear is considered negative
- 100 high field each with at least 20 WBC
43
What NCCLS criteria must be met before a thick smear is considered negative
300 fields Using 100x oil immersion objective
44
What are the advantages of antigen detection tests for W. Bancrofti
Sensitive Specific Tells active infection
45
Which antigens are used in malaria diagnosis
Histidine, rich, protein 2 (HRP 2) Plasmodium lactates dehydrogenase (pLDH)
46
Which antigen is specifically used to detect plasmodium falciparum
Histidine Rich Protein 2
47
The plasmodium, lactate, dehydrogenase essay is used to detect which species of malaria
Falciparum, species, and non-falciparum species
48
What are the steps to the optimal, rapid malaria diagnostic test?
1) Dispense 30 µL of buffer into the well at 10 µL of blood -mixed well 2) add optimal test strip, allow sample to wake up the test strip 3) move the test trip to a second wash well containing buffer 4) read the test strip after the blood color has cleared ~ 15 minutes
49
Describe what a negative valid rapid malaria test would look like
The contra antibody would be colored however, there would be no color on the anti-malaria antibody for all species, which is a second line. There would be no color on the Al foam antibody, which is the third line.
50
Describe what a positive valid rapid malaria test for p. falciparum species would look like
There would be colour on the control line Colour on the anti-malaria species (all), and colour on the anti-falciparum species
51
Describe what an invalid positive test for non-falciparum species would look like
No colour on the control line- INVALID Colour on the anti-malaria (all species) line
52
What are the advantages of the new diagnostic: antigen detection test for W. Bancrofti
- test positive day and night - uses finger prick blood - high sensitivity and specificity - rapid (1-10mins) - affordable - field usable - commercially available
53
List two common zoonotic parasitic diseases that affect humans
Eosinophillic Meningitis -angiostrongylus cantonesis Cutaneous Larva Migrans - Ancylostoma Caninum
54
What animals are the host for angiostrongyloides cantonesis?
Rats Snail (intermediate)
55
What animals are the host for Ancylostoma caninum
Dogs and cats
56
How is Eosinophillic Meningitis (Angiostrongyloies cantonesis) diagnosed
On Western Blot
57
Which parasite is also known as rat lung parasite?
Angiostrongyloides cantonesis
58
List two species of toxocariasis
Toxocariasis canis Toxocariasis Cati
59
List three diseases that can arise from toxocariasis infection
- Visceral Larva Migrans -Ocular Larva Migrans - Covert toxocariasis (asthma-like syndrome)
60
List 4 treatment options for cutaneous larva migrans
Oral thiabendazole Topical Thiabendazole Albendazole Ivermectin
61
What is the disadvantage of using antibody detection for malaria?
dignostic titres develop slowly and do not differenciate species (except falciparum)
62
What is the disadvantage of using antibody detection for filarial agents?
the antigen cross-react with those from other nematodes The presence of a filarial antibody in an assay, fails to distinguish between past and current infection
63
What antibody detection test is used for malaria?
IFAT - Indirect immunofluorescence
64
WHat antibody detection test is used for toxoplasmosis
ELISA IFAT (IgM)
65
What antibody detection test is used for toxocariasis
ELISA excretory -secretory (ES) antigens
66
What antibody detection test is used for Angiostrongylus Cantonesis
Western blot - 31kDa antigen on adult worm
67
Which antibody tests are used for Chagas disease
IFAT ELISA CFT (complement fixation test)
68
Which antibody test is used to detect Visceral Leishmaniasis?
IFAT ELISA
69
When would you use molecular detection (PCR)to diagnose a parasitic infection/disease
- when microscopic and immunodiagnostic procedures fail to establish the probable diagnosis - in the detection of infection from low parasitized patient's/ asymptomatic
70
Describe what a xeno-diagnosis is and which disease it is used for
Xeno-diagnosis is one in which the vector is experimentally infected with the humans blood Chagas disease
71
What specimen is used for diagnosis of a patient with leishmaniasis with in vitro culture (NNN Medium)
- Aspirates, scrapings or biopsy materials from skin lesions of patients with cutaneous leishmaniasis
72
List three ectoparasites
- Scabies - Pediculosis - Myasis
73
What is the name of the parasite that causes scabies?
Sarcoptes scabiei
74
What are the names of the three parasites that causes pediculosis?
Pediculus humanus capitis (head louse) Pediculus humanus corporis (body louse) Pediculus pubis (crab louse)
75
What is myasis
Human infection with fly larvae
76
How are itch mites sampled and detected
sampled by the scrapings from end of burrows sampled at 6 different sites (minimum) identify mites, eggs by microscopy
77
What is the scientific name of the parasite (screw worm)that causes myasis
Cochliomyia hominovorax (screw worm fly)
78
What is the scientific name of the parasite (bot fly) that causes myasis
Dermatobia hominis
79
What is the main difference in physical appearance between the Cochliomyia hominovorax and the dermatobia hominis?
Cochliomyia hominovorax has spiral spines, while the dermatobia hominis has transverse spines, sclerotized mouthparts, and a pair of projecting spiracles at the posterior end
80