Chapter 10 



Objects which may be confused with 



blood-inhabiting protozoa 



in stained films 



CERTAIN artifacts and extraneous objects occur fre- 

 quently in stained blood films. In spite of the precau- 

 tions taken during the preparation, there will be seen a 

 number of objects not present in the blood originally, 

 because of chance contaminations of tue blood film by 

 various animal or plant organisms, dust particles, particles 

 suspended in reagents and stains, etc. 



Free-living protozoa. Thev may occur in long-standing 

 distilled water, especially in warmer climate, and if it is 

 used for dilution of the stain, some of them may adhere to 

 the blood film and be stained. If flies or other insects drop 

 faecal matter on the drying blood film, intestinal flagellates 

 and other microorganisms may contaminate it. 



Dust particles. Dust particles from air or suspended in 

 water, stain, etc., may adhere to the film and simulate 

 malarial pigment. Scratches or breaks in the slide may 

 take up the stain, and resemble trypanosomes. 



Plant organisms. Yeasts, fungi, and bacteria may be 

 found in the film, often originating in the skin or air. Blood 

 films made post-mortem, may contain them as they may 

 have invaded the blood shortly before or just after death. 

 They may be confused with young stages in Plasmodium, 



Erythrocytes. Normal erythrocytes are circular in outline 



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