Answer to Case 543

Answer toParasite Case of the Week 543:Cryptosporidiumsp. oocystsThe case shows howCryptosporidiumoocysts look in a variety of different preparations including phase contrast (very cool). As we are all taught during training,Cryptosporidiumspp. oocysts are red-pink using a modified acid fast stain (as shown in image 3 of this case) and measure 4-6 micrometers in diameter, thus allowing their differentiation from the similarly-appearingCyclospora cayetanensisoocysts (which are 8-10 micrometers in diameter). Florida Fan reminded us that not all of the oocysts will reliably stain with the modified acid fast stain, and thus some may appear as ' ghost ' cells or negative outlines. A modified safranin stain can also be used and has been reported to more reliably stain the oocysts.Florida Fan mentioned that the direct fluorescent antibody (DFA) forCryptosporidiumspp. oocysts - widely regarded as the most specific microscopic method - doesn ' t necessarily detect allCryptosporidiumspecies, and thus there is the potential false negative results. In certain cases, confirmation with another method may be helpful.Finally, Old One tells a tale of prior infection in our case comments that he thankfully survived! It is indeed possible that his prior infection stimulated development of a protective immune response - likely an interferon-gamma mediated memory T cell response. However, it is not clear if this immune response would prevent future infections with all different species ofCryptosp...
Source: Creepy Dreadful Wonderful Parasites - Category: Parasitology Source Type: blogs