Chapter 9 



Technique for detection and identification 



of protozoa parasitic in the 



circulatory system 



TJiin film. The finger tip or ear-lo]:)e is cleaned with 70% 

 alcohol. Prick it with an aseptic blood lancet or a steri- 

 lized needle. Wipe off the first drop with gauze and receive 

 the second drop on a thoroughly cleaned (p. 54) slide about 

 half an inch from an end (Fig. 26, 1). Use care not to let 

 the slide touch the linger or ear-lobe itself. Quickly bring 

 a second slide, one corner of which had been cut away, to 

 the inner margin of the blood drop (Fig. 26, i), and let the 

 blood spread along the edge of the second slide. Next push 

 the second slide over the surface of the first slide at an 

 angle of about 45 towards the other end (Fig. 26, ^). Thus 

 a thin film of blood is spread over the slide (Fig. 26, 3). Let 

 the smear lie horizontallv and dry. It should he covered 

 with a glass cover to prevent dust particles from falling on it 

 and to exclude flies or other insects. If properly made, the 

 film is made up of a single laver of blood cells with 

 smoothlv rounded natural outlines. 



Thick film. Often parasites are so few that to find them in 

 a thin film involves a great deal of time. In such cases, a 

 thick film is advocated. For this 4-6 drops of blood are 

 placed in the central area of about /2 square inch, and with 

 a needle or a corner of slide, spread them into an even 

 layer. Let the smear drv, protecting it from dust or flies. 



97 



