This document discusses thick and thin blood films for detecting malaria parasites. It describes how thick blood films are best for detecting parasites due to examining a larger blood sample, while thin blood films allow identification of parasite species by showing morphological features. The staining and microscopic examination of blood films is an important technique for malaria diagnosis and management.

1. Blood Film for Malaria
Thick and Thin Blood Film
Hawler Medical University – College of Medicine
Prepared by:
Ibrahim Hussein
Ahmad Mazn
Aram Majeed

2. Objectives
 The purpose of thick and thin blood film
 Procedures of thick and thin blood film
 Stains used for thick and thin blood film
 Microscopic features of thick and thin blood film
 Advantages and disadvantages of thick and thin
blood film

3. Blood film
 When a peripheral blood sample is smeared on a
slide and stained, it is known as a peripheral
blood film (peripheral blood smear).
 The most commonly used technique for blood
examination

4.  There are two types pf blood film which are:
1- Thick blood film
2- Thin blood film

5. The Purpose of Blood film
 It allows for examination of the physical
characteristics of the red cells, white cells and
platelets under the microscope.
 It helps detect parasites or abnormal cells in the
blood.
 Examination of blood films is important in the
investigation and management of infections, wide
range of illnesses, including detection of blood-
borne parasites, like malaria.

6. The Purpose of thick and
thin blood films
 A thick blood film is a drop of blood on a glass
slide. Thick blood smears are most useful for
detecting the presence of parasites because
they examine a larger sample of blood. (Often
there are few parasites in the blood at the time
the test is done.)
 A thin drop of blood that is spread across a large
area of the slide. Thin blood smears helps
doctors discover what species of malaria is
causing the infection.

7. Procedure of preparing a
blood film
Three basic steps to make blood film:
1- Preparation of blood film.
2- Fixation of blood film.
3- Staining of blood film.

8. Preparation of blood film
1- Get ready clean microscopic slide.
2- Blood is obtained from the tip of a finger or a heel or big toe (in infants). The
skin should be carefully cleaned with ether or ethanol, and allowed to dry. Use a
sterile lancet prick the finger, wipe off the first drop then squeeze gently to obtain
a good drop of blood.
3- Place blood on clean glass slide to make thick and thin blood.
4- For a thick blood film:
 Touch the drop on a glass slide.
 Then spread the blood evently with the corner of another slide to make a square
or a circular patch of moderate thickness (with a diameter of 1-2 cm), it should
be possible to read through it.
 Dry the slide, while protecting it from dust, flies and insects.

9. Preparation of blood film
5- For a thin blood film:
 The drop of blood should be smaller than for the thick film.
 Apply the edge of another glass slide to the top of the drop of blood at an
angle of 45°, allowing the blood to spread along its edge, then push the
spreader slide forward keeping it at the same angle.
 A properly made thin film should consist of an unbroken layer of red blood
cells with the tongue of the film not touching the edge of the slide. The
thin film must be dried immediately by waving the slide from side to side or
by holding it for a few seconds in front of a fan this ensures a good
preservation of the shape of the cells.

11. Good blood films Poor blood films
Lipemia
Roeleaux

12. Stains used for thick and thin blood film
• Giemsa’s stain
• Leishman’s stain
• May-Grunwald stain
• Jenner’s stain
• Jenner-Giemsa
• These stains allow for the detection of WBCs,RBCs, and
platelet abnormalities

13. Staining principles used for thick and
thin blood film
 Many differential stains have been developed for
the detection of malaria parasites but the
Romanowsky stains that stain the nucleus red
and cytoplasm blue have proved the most
adaptable and reliable for routine work.
 Prior to staining, cells must be fixed to the glass
slide with acetone-free methanol, either alone or
in solution with dye. Addition of a buffer solution
to the dye changes the pH of the solution and
ionizes the reactants to initiate the pH-
dependent staining process.

14. Staining principles used for thick and
thin blood film
 Acidic cellular elements such as nucleoproteins,
nucleic acids and primitive cytoplasmic proteins,
react with the basic dyes, methylene blue and its
oxidative products. These elements are basophilic
and stain variations of blue.
 Basic cellular elements such as hemoglobin
molecules and some cytoplasm of WBCs, have an
affinity for the acidic dye, eosin. These elements
are acidophilic and stain orange-red.

15. Microscopic features of thick and
thin blood film
• Plasmodium are always intracellular, blue cytoplasm with red
chromatin.
• We can see ring stage, schizont & merozoit inside RBCs.
• Plasmodium spp; all asexual stage are seen.
• Plasmodium falciparum; only ring stage and gametocytes are seen.

16. P.falciparum
Schizont
Gametocyte

17. Gametocyte
Schizonts
P.vivax

18. Advantages and disadvantages of
blood film
Thick film:
 Advantage: more sensitive to detect the
parasite than thin film.
 Disadvantage: morphologic feature are not
seen, so the species are not identified.

19. Advantages and disadvantages of
blood film
Thin film:
 Advantage: morphology is better seen, so the
species are identified.
Disadvantage: because less amount of blood
is examined, so it is not sensitive for detecting the
parasite.

20. Summary
 Blood film allows for examination of the physical characteristics of
the red cells, white cells and platelets under the microscope.
 It is the most commonly used technique for blood examination.
 Thick blood smears are most useful for detecting the presence of
parasites while thin blood smears helps doctors discover what
species of malaria is causing the infection.
 Giemsa’s stain and Leishman’s stain are stains most commonly
used for staining blood films
 For malaria Romanowsky stains commonly used which stain the
nucleus red and cytoplasm blue.