378 



LABORATORY DIAGNOSIS OF PROTOZOAN INFECTIONS 



In examining preparations under the 

 microscope, move the slide systematic- 

 ally back and forth or up and down in 

 order to bring every part of the prepara- 

 tion into view. 



Iodine Slaiiii>ig. In order to bring 

 out certain details which are not visible 

 in the living protozoon, wet smears may 

 be stained with iodine. Prepare a fecal 

 suspension slightly heavier than that des- 

 cribed above, and mix it with an equal 

 amount of D'Antoni's aqueous iodine solu- 

 tion or of 1 part of Lugol's solution dilu- 

 ted with 4 parts of distilled water. 



DIRECT MICROSCOPIC 



EXAMINATION OF 

 INTESTINAL MUCOSA 



This technic can be used only in ani- 

 mals which have been killed and have had 

 their intestinal tracts opened. It permits 

 a greater amount of material to be exam- 

 ined on a single slide than does the direct 

 examination of diluted feces. It can be 

 used to find the intracellular and extra- 

 cellular stages of coccidia, other protozoa, 

 small nematodes such as Slrongyloides and 

 Capillaria, small trematodes, cestodes or 

 cestode scolices, and schistosome eggs. 



Make a rather deep scraping of the 

 suspected intestinal mucosa with a scalpel, 

 toothpick or similar instrument, or even 

 with the end .of a slide. Place the material 

 thus obtained on a microscope slide and 

 cover with a coverslip. Press the cover- 

 slip down if necessary to flatten out the 

 preparation and make it thin enough to see 

 thru. 



To search for Trichomonas, Giardia, 

 Hexamita and other motile flagellates, mix 

 a little physiological salt solution with the 

 scraping before placing the coverslip on it. 



MICROSCOPIC DIAGNOSIS 

 OF rRITRICIIOMONAS FOETUS 

 INFECTIONS 



In heavy infections of female cattle, 

 T. foetus can be found by direct micro- 

 scopic examination of mucus or exudate 



from the vagina or uterus. In aborted 

 fetuses it can be found in the amniotic or 

 allantoic fluid, fetal membranes, placenta, 

 fetus stomach contents, oral fluid or other 

 fetal tissues; it occurs most commonly in 

 the stomach contents and the material 

 around the base of the tongue. In bulls, 

 it can be found in the sheath cavity. 



Clean the external genitalia thoroughly 

 before taking samples in order to avoid 

 contamination with intestinal or copro- 

 philic protozoa. Take samples from the 

 vagina by introducing about 10 ml of 

 physiological salt with a bulbed dose 

 syringe and washing it back and forth sev- 

 eral times by squeezing the bulb repeat- 

 edly. Take samples from the preputial 

 cavity of bulls in the same way, using a 

 long, bulbed pipette or syringe, or intro- 

 duce a cotton swab into the cavity and rub 

 it around to obtain a sample of exudate; 

 in the latter case, wash off the swab in 

 physiological salt solution. 



Allow the washings to stand 1 to 3 

 hours or centrifuge them before examina- 

 tion. Place a drop of the sediment on a 

 slide, cover with a coverslip, and exam- 

 ine under the microscope. 



If trichomonads cannot be found on 

 direct microscopic examination, inoculate 

 some of the washings into CPLM, PGPS 

 or Diamond's medium, and examine after 

 1, 2 and 4 days' incubation at 37° C. 



SPORULATION OF 

 COCCIDIAN OOCYSTS 



In order to identify coccidia, it is 

 often necessary to allow the oocysts to 

 sporulate (i.e., to develop to the infective 

 stage). To permit this, mix feces con- 

 taining the coccidia with several volumes 

 of 2. 5% potassium bichromate solution and 

 place the mixture in a thin layer in a petri 

 dish. The potassium bichromate prevents 

 bacteria from destroying the oocysts. 

 Oxygen is necessary for the oocysts to de- 

 velop, so the layer of fluid should never 

 be more than a few millimeters thick. In 

 most species, sporocysts and sporozoites 

 form in a few days, but it is well to allow 

 development to proceed for a week (or, 



