Fecal Analysis & Intestinal Parasite Identification

Vocabulary flashcards summarizing major techniques, sample handling steps, and diagnostic parasite features from the fecal analysis lecture.

Fresh fecal sample requirements

Collect at least 5 g of feces less than a few hours old; place in an air-tight container and refrigerate if processing is delayed to prevent desiccation, bacterial death, and parasite egg hatching.

Direct smear

A tiny amount of feces mixed with a drop of saline on a slide and covered with a coverslip; best for observing Giardia trophozoites and bacterial motility under 40×.

Passive flotation

Method where 1 g of feces is mixed with zinc-sulfate solution in a fecalyzer/ovatector, filled to form a meniscus, covered with a coverslip, and left 10 min so ova/cysts float and adhere to the coverslip.

Centrifugal flotation

Large fecal sample mixed with flotation solution, strained, filled in a centrifuge tube, then spun (≈3,400 rpm); yields more ova/cysts than passive flotation by separating them from heavier debris.

Flotation solution (zinc sulfate)

High specific-gravity liquid that causes parasite ova and protozoan cysts to float while heavier debris sinks during flotation procedures.

Fecalyzer / Ovatector

Commercial container used in passive flotation to hold the zinc-sulfate mixture and support the coverslip during the 10-minute flotation period.

Hookworm ova

Large, oval to slightly elliptical eggs with a thin, colorless membrane; easily visible at 4× magnification.

Whipworm (Trichuris) ova

Football-shaped, dark brown eggs with a colorless operculum (plug) at each end; large and visible at 4×.

Pinworm (Enterobius) ova

Elliptical eggs that are flatter on one side, often pointed at one or both ends, surrounded by a double-thick colorless membrane.

Ascarid (Toxocara / Parascaris) ova

Asymmetrically round to slightly oval, tan-brown eggs with a thick, lumpy outer coat.

Toxascaris leonina ova

Round to slightly oval eggs, colorless to light brown, with a smooth outer membrane and a wavy inner membrane.

Dipylidium caninum ova

Irregular, oblong egg packets containing multiple developing tapeworm embryos.

Taenia spp. ova

Small, round to oval eggs with a thick, striated brown shell; contain a single embryo with visible central hooklets.

Fluke (trematode) ova

Very large, thumbprint or leaf-shaped golden-brown eggs possessing a distinct single operculum.

Cystoisospora cyst

Small, egg-shaped protozoan cyst resembling a halved avocado or hard-boiled egg; much smaller than helminth ova.

Giardia cyst

Tiny, oval protozoan cyst with four nuclei and a median line; smaller than Cystoisospora cysts.

Toxoplasma cyst

Extremely small, round to slightly oval protozoan cyst; may be unsporulated (single round body) or sporulated (two elongated ovals).

Normal bacterial flora in feces

Bacteria make up about 60 % of fecal mass; numerous motile rods of various shapes are always visible under 40× and are non-pathogenic.

Pollen grains

Environmental contaminants found in fecal samples; much smaller than parasite ova and best observed at 40×.

Yeast (normal gut flora)

Fungal cells routinely present in feces; generally non-pathogenic and part of normal microbiota.

Cyniclomyces guttulatus

A yeast species normal to rabbit gastrointestinal tracts; may appear in dog feces if the dog recently ingested rabbit droppings.

Straining step (centrifugal flotation)

Using woven gauze to remove large debris from the fecal-solution mixture before centrifugation, improving clarity and ova recovery.

Sample refrigeration

Storing fecal samples in a refrigerator when immediate processing isn’t possible to slow desiccation and preserve parasite stages.

Centrifugal vs. passive flotation

Centrifugation recovers more parasite ova/cysts than passive flotation because spinning separates them from heavy matter that would otherwise trap them.