Fuchsin fluorescence and autofluorescence in Cryptosporidium, Isospora andCyclospora oocysts

Cryptosporidium parvum and Isospora belli oocysts stained with carbol-fuchs in, as in a modified Ziehl-Neelsen technique, fluoresce bright red under gr een light (546 nm). Cryptosporidium oocysts tend to fluoresce more brightly the less intensely stained they appear under transmitted light; this is no t the case with Isospora. Fuchsin-stained Cyclospora cayetanensis oocysts f luoresce rather dimly, but those not taking the dye retain their typical au tofluorescence. Cryptosporidium and Isospora oocysts are also autofluoresce nt, appearing violet under u.v. light (365 nm), and green under violet (405 nm) and blue-violet light (436 nm). Their autofluorescence does not surviv e the staining procedure. (C) 1998 Australian Society for Parasitology. Pub lished by Elsevier Science Ltd. All rights reserved.