Incidence and intensity of Babesia spp. sporokinetes in engorged Boophilus microplus from a dairy herd in Venezuela.

The objective of this study was to determine the incidence and intensity of Babesia spp. sporokinetes in hemolymph of engorged females (EF) Boophilus microplus monthly detached from two herds of a local dairy breed of cattle named Carora breed. The experimental herds were located in 2 ranches, 45 km apart, having different management of tick control (TC). Proper methods of TC were commonly used at ranch "A," whereas ineffective methods were used at ranch "B," Babesia spp. sporokinetes were diagnosed in EF B. microplus by microscopic exam of tiny smears of hemolymph stained with Giemsa. A total of 537 smears were checked, and 108 were positive to Babesia spp. (20.1%). The incidence of Babesia spp. was higher (p < 0.01) in ranch "B," 22.3%, compared with the value detected in ranch "A," 6.5%. Incidence of Babesia spp. was greater in the dry season (Dec-Apr) compared with the values detected during the rainy season (May-Nov). The intensity of Babesia spp. was 3.43 at ranch "B" (p < 0.01), and 0.32 at ranch "A" during the rainy season. The values detected for intensity kept no correlation with those two seasons, although it is known that the incidence and seroprevalence of bovine babesiosis are greater during the dry season. The importance of these parameters in the epizootiology of bovine babesiosis in Venezuela is discussed.