4.5. Coproparasitological Test

Microscopic analysis for enteric protozoan cysts and/or trophozoites was performed according to the standardised procedures with the following methods: Concentration of samples—each faecal sample was concentrated by means of the commercial filter SpinCon (Meridian Biosciences, Cincinnati, OH, USA), which employs passive filtration and centrifugation through a series of two screens with successively smaller mesh. For the process of filtration 3 mL of surfactant treated, preserved stool specimens were manually transferred from their transport vials to the device for filtration. The surfactant consented to break down faecal aggregates, thus helping to release the parasites. This was followed by the physical blending of faecal material and the addition of 2 mL of physiological saline (for a total of approximately 5 mL diluted, filtered stool), to facilitate the concentration process. The faecal samples were then centrifuged at 500× g for 10 min, and the supernatant was eventually discarded into a suitable biohazard receptacle, thus producing a small pellet of a concentrated sample, which was examined microscopically for the presence of parasites. Direct microscopic analysis with extemporary staining was carried out, during which a small quantity of faecal material (about 2 mg) was diluted on a glass slide with Lugol’s iodine solution 1% (containing iodine crystals 2 g, potassium iodide 2 g, and distilled water 100 mL) stabilised with polyvinylpyrrolidone (PvPP). The specimen was then analysed using a low-power lens (10×) and low-intensity light by means of Kohler lighting. The ambiguous samples were further observed at 40×. Antigen detection was performed by immunochromatographic test (Stick Crypto/Giardia; Operon^®, Zaragoza, Spain) according to the manufacturer’s instructions