Answer to Case 457

Answer:Cyclospora cayetanensisoocystsThanks again to Florida Fan for providing these colorful images. Idzi Potters mentioned thatC. cayetanensisoocysts also produce beautiful autofluorescence. Instructions for observing their autofluorescence can be foundHERE) Below is an image that Florida Fan gave me a while back which nicely highlights this phenomenon (oocysts are denoted by arrows):Examination for autofluorescencing oocysts can be a quick way to screen forC. cayetanensisin stool, keeping in mind that other objects (including many non-parasites) will also exhibit autofluorescence. The regular size and smooth round shape of the oocysts usually allow them to be easily identified. Alas, the fluorescence scope in my lab doesn ' t have the correct filters for observing autofluorescence, so this is not a technique that I can use.Note that the oocysts ofC. cayetanensisare in an unsporulated (immature) stage when passed in feces and so you won ' t see sporozoites within them like you sometimes can withCryptosporidiumspp. oocysts. Instead you may just see globular material like in the figure A (wet prep; arrows) from this case:The immature nature of freshly-shedC. cayetanensis oocysts has an important impact on this parasite ' s epidemiology. Because the oocysts are shed in an unsporulated state, they must undergo further development in the environment before becoming infective. Once mature, soil or water containing the oocysts must then be allowed to contaminate foo...
Source: Creepy Dreadful Wonderful Parasites - Category: Parasitology Source Type: blogs