Taxonomy: f. Hexamitidae
Animal: Giardia intestinalis 13 18.jpg
Giardia intestinalis trophozoite - trichrome stain of faeces. Trophozoites are pear shaped 10-20x5-15 microns x 2-4 microns thick; 2 nuclei on either side of central axonemes- thin membrane with no granules and a large central karyosome; 4 lateral, 2 ventral and 2 caudal flagella -- often hard to see; 1-2 median bodies lie transversely below nuclei; depression -a sucking disc occupies 1/2 to 3/4 of ventral surface to adhere to epithelium; pear shaped front view but spoon shaped side view; have a falling leaf motion if seen in wet preparation. Although these parasites can be identified in wet smears, many infections are missed without the examination of a permanent stained smear. Also, because the trophozoites of Giardia are attached so firmly by means of their sucking discs in the mucosa; a series of even 5 or 6 samples may be examined without detecting the organisms. Incubation time for giardiasis is 12-20 days; the acute stage is brief but foul smelling, explosive diarrhoea plus lack of blood ,mucus or cellular exudate is consistent with giardiasis. A sub acute or chronic stage may continue with epigastric pain, abdominal distension, belching and weight loss and episodes of foul stools (Garcia & Bruckner, 1997).
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