Studies on the transmission of Theileria annulata to cattle by the tick Hyalomma lusitanicum

The role of the ixodid tick Hyalomma lusitanicum, Koch 1844 as a vector of Mediterranean or tropical theileriosis (caused by the protozoan parasite Th eileria annulata Dschunkowsky et Luhs 1904) in southern Spain was studied. Hyalomma lusitanicum was the most common tick, and the only species of the genus Hyalomma L., found on T. annulata-infected cattle from the theilerios is enzootic area Studied (province of Cadiz, southern Spain). Likewise, we found that all sera of the cattle previously considered as suspected of the ileriosis by clinical signs, tested for T. annulata antibodies, were positi ve and all blood samples of these suspected cattle examined had infected er ythrocytes. Partially fed H. lusitanicum adults mere collected in the field on T. annulata-infected cattle in this enzootic area and fed on an uninfec ted calf in an experimental farm free of theileriosis and ticks. At approxi mately 3 weeks post-tick feeding on the calf, this became positive for T. a nnulata antibodies and I: annulata merozoites were found in erythrocytes fr om blood smears. These results show the ability of H. lusitanicum to transm it the protozoan parasite T. annulata to susceptible cattle and indicate th at H. lusitanicum is probably an important vector of T. annulata in the enz ootic area surveyed.