Case #176 – March, 2006

A CDC microbiologist was looking through slide boxes that had been archived to determine whether the slide quality was good enough to continue storing them. He came across a pathology slide of heart tissue that was dated “1929.” Figures A-C show what was observed on the H & E stained preparation. What objects do you see in the images?

Figure A

Figure B

Figure C

The objects in the images are amastigotes. Determining the genus and species of a parasite is not possible based on morphologic features of amastigotes. The slide that was found was labeled, “Homo sapiens. Heart tissue infected with Trypanosoma cruzi, Chagas.” Diagnostic features included:

the amastigote form of the parasite (Figures A-C, within black circles), identified by the presence of a nucleus and a distinct, sometimes rod-shaped, kinetoplast (yellow arrows).
amastigotes that appear to be in the process of transforming into trypomastigotes (white circle, Figure A).

Figure A

Figure B

Figure C