Blood Parasites Flashcards
Enumerate the different blood parasites
- Plasmodium
- Trypanosoma
- Leishmania
- Babesia
- Dirofilaria immitis
- microfilariae
The most common method for detecting blood parasites.
Microscopic blood examination
What are the methods of collection for blood parasites?
Finger, Earlobe, Venipuncture (EDTA)
Factors that influence the timing of specimen collection
- travel history
- clinical symptoms
- periodicity (Plasmodium spp.,Babesia)
- end of paroxysmal episode (microfilariae)
This sample must be free-flowing to prevent dilution of blood with tissue fluid, which decreases the number of parasites.
Finger-prick blood sample
This is usually from a finger-prick blood sample
Wet/Fresh Preparation
These blood parasites are large and motile in fresh blood preparations.
Microfilariae and trypomastigotes
In this preparation, species identification is not possible.
Wet mount
It is prepared from 2 to 3 drops of blood and spread over a 2 cm diameter area.
Thick film
It is prepared in such a way that they are thick on one end and thin and feathery at the other end. This is done using two, clean glass slides (Wedge Method).
Thin smear
This is made in the same manner as a blood smear used for a differential count in hematology.
Thin Blood smear or Thin smear
The suggested “___________” or __________ assures that the thin area of the slide has one layer of evenly distributed cells.
Push Slide Technique and Wedge Method, respectively
How many drops of whole blood do you add when doing a thick blood smear?
2 to 3 small drops
What is the ideal portion of the thin film that should be examined for the presence of malaria?
Feathery end of the film
You need to examine __________ microscopic fields using oil immersion objective before a film is reported as negative.
one hundred
Objectives:
For detection of microfilariae-
For malarial parasites-
LPO
OIO
What does EDTA mean?
Ethylene diamine tetra acetic acid
Time of collection is very important for the recovery and identification of this blood parasite.
Microfilariae
These blood parasites are randomly collected, meaning it has no periodicity.
Leishmania and trypanosoma
The time of collection is very important for the recovery and identification of this parasite
Microfilariae
These are intraerythrocytic parasites that are best recovered from blood samples collected toward the end of a paroxysmal episode.
Plasmodium species and Babesia species
What type of smear is used in Malaria Parasite count?
Thick film
Its drawback include possible contamination because you might be extracting juices and not the blood especially when squeezing too much
Finger
The gold standard for blood collection
Venipuncture (EDTA)
It can only collect a very small amount of blood and clots easily thus, cannot come up with a good smear
Earlobe
This is allowed to dry and then dehemoglobinized
Thick film
Why do we dehemoglobinized thick films?
Because it aids to see the parasite easily when we do microscopy
Advantages and disadvantages of thick films
Advantage: Faster assessment and higher incidence of seeing a parasite.
Disadvantage: Not recommended for species identification
What happened when the slide has not been properly cleansed or the blood is too thick?
the blood may flake off the slide during staining
Why do we mix continuously for at least 30 seconds in doing thick film?
To prevent the formation of fibrin strands (but if anticoagulated blood is used, this step is eliminated).
Why should the dry slides in thick films be laked in buffer solution?
To remove hemoglobin
It is incorporated with the test kit already
Buffer solution
In doing a malaria parasite count, after counting 200 leukocytes, 10 or more parasites have been counted…
record the results showing parasites per 200 leukocytes
In doing a malaria parasite count, after counting 200 leukocytes, 9 or less parasites have been counted…
Continue counting until 500 leukocytes have been counted and record the parasites per 500 leukocyte
In doing a malaria parasite count, you select a part of the thick film that has?
best definition from the staining point of view and has about 20 leukocytes per field
In doing a malaria parasite count, you select a part of the thick film that has?
best definition from the staining point of view and has about 20 leukocytes per field
To convert parasites per # of leukocytes to parasites per ul, use the formula:
of parasites/ ul = # of parasites counted x 800 / # of leukocytes counted
If 200 leukocytes are counted, you multiply by?
40
If 500 leukocytes are counted, you multiply by?
16
