Manual of basic techniques for a health laboratory - libdoc.who.int

4. Parasitology 133Fig. 4.42 Ancylostoma duodenale eggsin fresh stoolsFig. 4.43 Ancylostoma duodenaleegg in stools a few hoursoldFig. 4.44 Ancylostoma duodenaleegg in stools 12–48 hoursoldFig. 4.45 Fertilized Ascarislumbricoides eggwith double shellFig. 4.46 Unfertilized Ascarislumbricoides eggwith double shellFig. 4.47 Semi-decorticatedfertilized Ascarislumbricoides eggFig. 4.48 Semi-decorticatedunfertilized Ascarislumbricoides eggType B. Unfertilized egg with double shell (Fig. 4.46)Size: 45–90mm (larger than type A).Shape: more elongated than type A (elliptical or irregular).Shell: the two shells are indistinct:— the external shell is brown and puffy, with rather jagged lumps— the internal shell is thin (one or two lines may be visible).Content: the egg is full of large, round, very shiny granules.Type C. Semi-decorticated fertilized egg (Fig. 4.47)Similar to type A but without the external shell.Shell: single, smooth, thick and colourless (or very pale yellow).Content: a single round, colourless, granular central mass.Type D. Semi-decorticated unfertilized egg (Fig. 4.48)Shell: single, smooth, thin and colourless (double line).Content: large, roundish, colourless, shiny granules.Caution: Do not confuse type D with Ancylostoma duodenale, Fasciola spp. orFasciolopsis buski eggs.