Lab Diagnosis of Blood Parasites Flashcards

1
Q

What are the 5 types?

A
Falciparum 
Vivax
Ovale 
Malariae
Knowlesi
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2
Q
Falciparum 
Vivax
Ovale 
Malariae
Knowlesi 

Which one is not common in Africa?

Which one is not common and doesn’t have geographical distribution

Which one is only confined to SE asia?

A

P. Vivax

P. malariae

P. Knowlesi

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3
Q

Lab tests:

FBC

Quantitative Buffy Coats (QBC)

Thick and Thin Films

Immunochromatographic Rapid Diagnostic Tests

PCR

Antibody detection using immunoassays or fluorescence techniques

A

Lab tests:

FBC

Quantitative Buffy Coats (QBC)

Thick and Thin Films

Immunochromatographic Rapid Diagnostic Tests

PCR

Antibody detection using immunoassays or fluorescence techniques

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4
Q

Lab Tests:

FBC:

  • What is a common finding on the platelet count?
  • What happens to WBC count?
  • What does cytometry do?

Qualitative Buffy Coat Screening (QBC):
- What does this do?

A

Thrombocytopenia - 80% of cases

Reduced neutrophils/leukocytes

Cytometry gives you an idea of the RNA/DNA information, the internal cell structure and the cell volume

The quantitative buffy coat (QBC) technique is a method of diagnosing malarial parasites based on micro-centrifugation, fluorescence, and density gradient of infected red blood cells.

They separate into distinct layers according to their density. it is stained and then examined under a fluorescent microscooe

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5
Q

Lab Tests:

Thick and Thin Films - GOLD STANDARD FOR MALARIA:

Blood spread on a slide and examined.

Thick films:
- What are they most useful at detecting?

Thin films:

  • What are they most useful at detecting?
  • It is less sensitive than the thick film!
  • What may they be able to see on a microscope?

Which one is fixed in methanol?

What is important to remember?

A

Presence of parasites - parasitemia

Detect species of parasite causing the infection - see malarial parasites to be seen within the RBC and to assess the size of infected vs uninfected RBCs

Quantify parasitemia
Recognise parasite forms - schizonts and gametocytes

Thin films only

A negative malaria film does not exclude a diagnosis of malaria. If there is a strong suspicion of malaria but the initial films are negative then repeat films should be requested 12-24hrs and 48hrs.

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6
Q

Lab Tests - NOT USED ACUTELY:

Immunochromatographic Rapid Diagnostic Tests - what is the main issue with this type of testing?

PCR:

  • What does it detect?
  • What is the main use?

Why are malarial antibodies not tested for acutely?

A

Unreliable - not available in an acute setting
False positives
====
Parasite nucleic acids

Confirming the species of malarial parasite after the diagnosis has been established by either smear microscopy or RDT.

Appear of days or weeks
Good for screening for donors and studies

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