Fluorescein diacetate staining of Anaplasma marginale as a possible measure of viability.

Fluorescein diacetate viability-staining technique was applied to Anaplasma marginale. Marginal bodies took up the stain and became fluorescent. When infected red blood cells were incubated at 55 C, the number of fluorescent Anaplasma decreased at a rate similar to the known loss of viability.