DIAGNOSIS OF THEILERIA-ANNULATA INFECTION OF CATTLE IN TUNISIA - COMPARISON OF SEROLOGY AND BLOOD SMEARS

The immunofluorescent antibody test (IFAT) using schizont and piroplas m antigens was compared with the microscopic examination of Giemsa-sta ined blood smears for the diagnosis of Theileria annulata infection in experimentally and naturally infected cattle. The results obtained on 100 naive cattle showed that non-specific fluorescence disappeared at serum dilution levels of 1/40 and 1/160 for the piroplasm and schizon t antigens, respectively. These levels were therefore retained as the starting dilutions for this study. On day 30 post-infection, 16 experi mentally infected calves were shown to be serologically positive for s chizont and piroplasm IFAT, while 13 of them were positive for blood s mears. A total of 109 cattle from an endemic region of tropical theile riosis were sampled before the onset of the disease season in April an d later in September. Globally the IFAT results revealed more cattle e xposed to T annulata infection than the blood smear examination. The p iroplasm IFAT and the blood smears were less reliable than the schizon t IFAT. The latter appeared to be the best test for detecting exposure to T annulata.