Infected section of heart muscle

Thin section of heart muscle (haemotoxylin & eosin stain) showing amastigote - or host - stage of Trypanosoma cruzi, the protozoan parasite that causes the wasting Chagas disease. Amastigotes multiply, destroying adjoining tissue, and form pseudocysts (localised collections of fluid). The darkly stained, rod-like kinetoplasts - oversized mitochondria containing granules of DNA - are visible.