Sunday, July 10, 2011

Answer to Case 168

Answer: Trypanosoma cruzi trypomastigotes (flagellated forms)

Thanks to everyone who wrote in with the answer to this case - you were all correct!

EST2010points out that this organism "is transmitted through excrement from the Reduviid or 'kissing bug' found throughout S. America. Key differentiating features from African trypanosomes (T. brucei rhodesiense and T. brucei gambiense) include the very enlarged posterior kinetoplast, the curved 'C' shape and geography." Neuro_Nurse further notes that "the swollen eye is known as RomaƱa sign." So you all picked up on the clues that I gave you for this case.

Here is an image comparing the size of the kinetoplast between T. cruzi and T. brucei (the most important differentiating feature):

Although I've shown you the classic "C" shape of T. cruzi, note that this is not a reliable feature for identification, since T. brucei subspecies can also take on a "C" shape.

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