A comparison of five staining methods for detection of Cryptosporidium oocysts in faecal specimens from the field

Five staining methods for identification of Cryptosporidium oocysts in faecal smears were evaluated using samples obtained from asymptomatic south Indian villagers of all ages. The safranine-methylene blue technique was used as the gold standard and compared with 2 methods each using auramine and mepacrine, with potassium permanganate and carbol fuchsin as counterstains. All five methods identified all samples containing cryptosporidium oocysts, however false positive identifications were obtained by the standard auramine-phenol-potassium permanganate method. The auramine-carbol fuchsin and the mepacrine-carbol fuchsin techniques are the simplest and most rapid of the five methods compared. The mepacrine-carbol fuchsin technique is recommended for screening large numbers of stools, since it does not stain yeasts, is cheaper and less toxic than auramine.