Many different technics have been 

 used for the laboratory diagnosis of pro- 

 tozoan infections and for the study of para- 

 sitic protozoa. Only the commonest and 

 those which have been found most useful 

 in the author's laboratory are given here. 

 Other routine and specialized technics are 

 given by Craig (1948), Hoare (1949), Kirby 

 (1950), and various textbooks of human 

 parasitology. 



Some of these technics are useful not 

 only for protozoa but also for helminth 

 eggs or larvae. If so, their value for 

 these purposes is mentioned. 



Chapter /4 



DIRECT MICROSCOPIC 



EXAMINATION OF WET 



FECAL SMEARS 



Place a drop of physiological salt so- 

 lution on a microscope slide. Take up a 

 small amount of feces on the end of a 

 toothpick and mix thoroughly with the salt 

 solution. Do not make too heavy a sus- 

 pension, or it will be impossible to see 

 objects clearly under the microscope. An 

 emulsion thru which newsprint can be read 

 is about right. Place a coverslip on the 

 drop. Examine under the low and high dry 

 powers of the microscope. 



Flagellates and ciliates can be seen 

 moving about actively. Amoebae may 

 move sluggishly or may remain still. 

 Oocysts of coccidia and helminth eggs can 

 be recognized from their shape and size. 

 Many other objects will be seen, some of 

 which may be mistaken for protozoan 

 parasites. These include bacteria, yeasts, 

 fungus spores, the fungus Blastocystis, 

 pollen grains, undigested food particles 

 such as starch grains and plant fibers, 

 and ingested pseudoparasites such as 

 grain mites or coccidian oocysts of ani- 

 mals which have been eaten by or have 

 defecated in the feed of the animals under 

 examination. In cases of enteritis, red 

 or white blood cells or epithelial cells 

 may be present. 



LABORATORY 



DIAGNOSIS 



OF 



PROTOZOAN 



INFECTIONS 



377 



