Detection of Babesia bovis in cattle by PCR-ELISA.

We established a new highly sensitive method, PCR-ELISA, for the dectection of Babesia bovis in cattle for farms in Thailand. The detection of around 2.4 x 10(-8)% parasitemia (equivalent to 1 infected erythrocyte per 2 ml) was achieved by PCR amplification followed by the ELISA detection of a biotin tagged gene. When comparing the sensitivity of PCR-ELISA with the microscopic method, our PCR-ELISA method is more sensitive than thin blood smears by at least 1,000 times. The established PCR-ELISA also showed high specificity to B. bovis with no cross reaction to other endemic parasites except for A. marginale. Regarding the detection threshold for B. bovis, the PCR-ELISA method could detect parasites inoculated into splenectomized calves at least 1 week earlier than the thin blood microscopic method. The PCR-ELISA method is a valuable screening technique for B. bovis and applicable for the routine detection of carrier states and automated analysis.