MALARIA DIAGNOSIS WORKSHOP

29 JUNE – 2 JULY 2010

PREPARATION OF BLOOD

FILM FOR MALARIA

PARASITES

Two types of blood film for malaria parasites

Thick Blood Smear – use to determine if parasite is present.

Thin Blood Smear – use to confirm the Plasmodiumspecies present

Before making blood film…

Wear gloves prior to taking blood samples or handling blood.

Avoid getting blood, including dry blood from films, on your fingers or hands.

Cover cuts on your hands with waterproof dressing.

Avoid accidentally pricking yourself when handling sharp instruments

Wash your hands with soap and water after you finish a job.

If you get blood on your skin, quickly wipe it off with a cotton swab dampened with alcohol; then, wash the affected area with soap and water as soon as

possible.

Materials for Preparation of Malaria

Smears

Clean and wrapped slides

Sterile lancets

70% ethanol and water

Absorbent cotton wool

Surgical gloves

Lint-free cotton cloth

Slide box or cover to exclude flies and dust

Record form or register

Soft lead pencil; ball-point pen

PROCEDURES:

1. RECORD PATIENT DETAILS ON A REGISTER

Get ready clean

microscopic slide

glass slides of

superior’ quality, with

frosted end.

The frosted end

should be used to

label the slide.

PREPARATION OF BLOOD FILM FROM

FINGERPRICK

2. Wear glove and hold

the patient’s left hand

with palm facing upwards.

Select third finger from

the thumb

The thumb should never

be used for adults or

children.

Note : Good films may be prepared

directly from fingerprick blood,

Clean the finger with

a piece of cotton wool

lightly soaked in 70%

ethanol.

Dry the finger with a

clean cotton cloth,

using firm strokes to

stimulate blood

circulation.

For infant – use the

toe

4. Use sterile lancet to

prick the finger

5. Apply gentle pressure

to the finger to allow

the blood to ooze out

6. Wipe off the first drop

7. Apply further gentle

pressure for more

blood

8. Place blood on clean

glass slide to make

thick and thin blood

film on a slide

Place the spreader

slide in contact with

the drop of blood at

an angle..

Let blood spread

along the edge of the

spreader slide.

gently push towards

the other end of the

slide

Thin Blood Film

Angle too flat

> film too long

Angle too steep

> film too short

Thin Film Good preparation - feathered end of

the film should be centrally located on the slide with free margins on both sides,

when properly prepared, it will be only one cell layer thick at this end.

Badly prepared smears can cause presence of streaks - as a result of chipped spreader

holes in the film indicate faulty preparation and dirty or greasy slides, respectively.

Combination of thick and thin blood on the same slide

OK

TOO MUCH BLOOD

Thick blood film – spread the drop of blood using a corner of the spreader.

Spread the drop in one circular direction to make even thick film, size of a 1 cm diameter. Do not stir the blood.

Preparation of thick blood film using …….

Plastic pipette

Using wooden stick

Good thick blood film

• The right thickness,

• You should be able to

read the newspaper,

Avoid doing these

Thick film too thickIt should be round

Labeling

With frosted end

use a pencil

Without frosted end

use diamond pencil

Do not label on the

blood film

Do not use a ball pen

Do not use a paper

label

Drying slides

Incubator 37oC

Leave standing on a

rack on lab bench

In a slide tray with the

cover open

Hair dryer?

A fan?

Do not leave on the bench in a laboratory

unattended because it will be eaten by insects.

Slides must be dried completely before they

are packed for storage or transport.

Venous blood can be

used instead of from

finger prick

Use vacutainers with

anticoagulant (EDTA)

For preparing thin and

thick films use a glass

capillary to drop the

ETDA-blood.

plastic pipette ? Yes

provided no air bubles

The use of anticoagulated (EDTA) blood may cause the following :

smears require longer time to dry

thick smears tend to flake from the slide

stain quality is affected,

stippling of infected RBC’s may not be visible

parasite forms may be distorted and may lyse

RBC’s may become crenated and look fimbrinated

Prepare smears as soon as possible after

collecting venous blood (less than 2

hours after collection) to avoid:

Changes in parasite morphology

Changes in the RBC morphology

(these effects can compromise

correct identification of species)

Staining characteristics

YouThank

For your attention