Fluorescent antibody staining of four Babesia species

Fluorescein-conjugated globulins, prepared from serum of animals recovered from acute infections with Babesia argentina, B. bigemina, B. canis, and B. rodhaini, stained their homologous parasites. The staining showed features of the parasitized cell not seen in blood films stained by the Giemsa method. These were the specific fluorescence of the margins of erythrocytes parasitized by B. argentina and B. canis and of granules in erythrocytes parasitized by B. bigemina and, to a lesser extent, in those parasitized by B. argentina and B. canis. Neither of these features was seen in erythrocytes infected with B. rodhaini, fluorescein-globulin conjugates reacted only with the parasite. The possibility of the reaction of antibody with parasitized erythrocytes being of assistance to the host in removal of parasites is discussed