Autofluorescence of Toxoplasma gondii and related coccidian oocysts.

This is the first report of blue autofluorescence as a useful characteristic in the microscopic detection of Toxoplasma gondii, Hammondia hammondi, Hammondia heydorni, Neospora caninum, Besnoitia darlingi, and Sarcocystis neurona oocysts or sporocysts. This autofluorescence is of sufficient intensity and duration to allow identification of these oocysts from complex microscopic sample backgrounds. As with the autofluorescence of related coccidia, the oocysts glow pale blue when illuminated with an ultraviolet (UV) light source and viewed with the correct UV excitation and emission filter set.