Basic Malaria Microscopy (part I and II) (WHO - OMS, 1991, 72 p.): Learning Unit 9. Artefacts in blood films

Basic Malaria Microscopy (part I and II) (WHO - OMS, 1991, 72 p.)

		(introduction...)
		Preface
		Introduction
		Learning Unit 1. Malaria, the disease
		Learning Unit 2. Cleaning and storing microscope slides
		Learning Unit 3. Keeping accurate records
		Learning Unit 4. Blood films
		Learning Unit 5. Staining blood films with Giemsa stain
		Learning Unit 6. The microscope
		Learning Unit 7. Examining blood films
		Learning Unit 8. Examining blood films for malaria parasites
		Learning Unit 9. Artefacts in blood films
		Learning Unit 10. Routine examination of blood films for malaria parasites
		Learning Unit 11. Life cycle of the malaria parasite
		Learning Unit 12. Supervisory aspects of malaria microscopy
		Back Cover

Learning Unit 9. Artefacts in blood films

Learning objectives

By the end of this Unit you should:

· know that blood contaminants may be confused with malaria parasites
· recognize and be able to distinguish between malaria parasites and common artefacts
· know the various ways in which artefacts can contaminate blood films
· know how to prevent artefacts from contaminating blood films.

By this stage in your training you are likely to have seen a number of objects in blood films that have caused you some confusion; if you could not identify them as parasites you have probably wondered what they are.
Blood films may contain many features that can cause confusion and problems in diagnosis. Such features are known as artefacts. Some are more common than others; some are easier to prevent than others.
Fungus will show up as artefacts on blood films. The best way to prevent fungal growths on slides is to stain blood films as soon as possible after making and drying them - within 48 hours at most. Unfortunately, this is not always practicable.
Other contaminants will be picked up from the environment. Dust particles floating in the air will settle on blood films while they are drying, either before or after staining. Specks of dirt may be transferred from a patient’s finger when a blood sample is taken, or the original slide may not be perfectly clean.
Plate 3 shows a variety of artefacts that may be seen in both thick and thin blood films. The examples are not exhaustive but give a good idea of the size, shape and colour of different kinds of artefact.
You may occasionally see microfilariae (e.g. Wuchereria bancrofti) in blood films you are examining. These are not, strictly speaking, artefacts and you should report what you see, both on your record form and directly to your supervisor.

Microfilaria of Wuchereria bancrofti