SPOROGONY AND EXPERIMENTAL TRANSMISSION OF BABESIA-EQUI BY BOOPHILUS-MICROPLUS

The development of Babesia equi in salivary glands of adult female Boo philus microplus was observed under a light microscope using semithin sections stained with toluidine blue. Engorged nymphs were obtained fr om splenectomized foals experimentally infected with B. equi. As adult s, they were then fed on rabbits for 5 days and the salivary glands of manually collected individuals were removed at intervals of 24 h. Spo rozoites were found in type III granular acini cells between the 2nd a nd 5th days following feeding on the rabbits. Sporoblasts and sporozoi tes were observed in the same or adjacent acini cells in all the gland s examined. The formation of the sporozoites occurred following the mu ltiple division of the sporoblasts through a process of radial budding from the periphery of bodies resulting from multiple fission. Sporozo ites were detected in smears of adult males stained with Giemsa, betwe en the 2nd and 5th days following feeding by the ticks. Adults of B. m icroplus, fed during the nymphal phase on foals with patent parasitemi a, transmitted sporozoites of B. equi to a splenectomized foal. The ro le of B. microplus in the transmission and epidemiology of B. equi is discussed.