A reverse line blot (RLB) assay was developed for the identification of cattle carrying different species ofTheileria and Babesia simultaneously. We included Theileria annulata, T. parva, T. mutans, T. taurotragi, and T. velifera in the assay, as well as parasites belonging to theT. sergenti-T. buffeli-T. orientalis group. TheBabesia species included were Babesia bovis,B. bigemina, and B. divergens. The assay employs one set of primers for specific amplification of the rRNA gene V4 hypervariable regions of all Theileria andBabesia species. PCR products obtained from blood samples were hybridized to a membrane onto which nine species-specific oligonucleotides were covalently linked. Cross-reactions were not observed between any of the tested species. No DNA sequences fromBos taurus or other hemoparasites (Trypanosomaspecies, Cowdria ruminantium, Anaplasma marginale, and Ehrlichia species) were amplified. The sensitivity of the assay was determined at 0.000001% parasitemia, enabling detection of the carrier state of most parasites. Mixed DNAs from five different parasites were correctly identified. Moreover, blood samples from cattle experimentally infected with two different parasites reacted only with the corresponding species-specific oligonucleotides. Finally, RLB was used to screen blood samples collected from carrier cattle in two regions of Spain. T. annulata, T. orientalis, and B. bigeminawere identified in these samples. In conclusion, the RLB is a versatile technique for simultaneous detection of all bovine tick-borne protozoan parasites. We recommend its use for integrated epidemiological monitoring of tick-borne disease, since RLB can also be used for screening ticks and can easily be expanded to include additional hemoparasite species.

The role of the ixodid tick Hyalomma lusitanrcum Koch 1844 as a vector of Mediterranean or tropical theileriosis (caused by the protozoan parasite Theileria annul& Dschunkowsky et Luhs 1904) in southern Spain was studied. Hyalomma lusitanicum was the most common uck, and the only species of the genus Hyalomma L., found on 7: onndata-infected cattle from the theileriosis enzootic area studied (province of Cadiz, southern Spain). Likewise, we found that all sera of the cattle previously considered as suspected of theileriosis by clinical signs, tested for I: annulata antibodies, were positive and all blood samples of these suspected cattle examined had infected erythrocytes. Partially fed H. lusitanicum adults were collected in the field on 7: annulata-infected cattle in this enzootic area and fed on an uninfected calf in an experimental farm free of theilenosis and ticks. At approximately 3 weeks post-uck feeding o n the calf, this became posiuve for 7: annulata anubodies and 7: anndata merozoites were found in erythrocytes from blood smears. These results show the ability of H. Iuszfanzrum to transmit the protozoan parasite I: annul& to susceptible cattle and indicate that H. lusttanirum is probably an important vector of 7: annulata in the enzootic area surveyed.

In this work we studied the ability of a nested polymerase chain reaction (PCR) to detect Theileria annulata, the causative agent of Mediterranean theileriosis, in blood samples obtained from cattle on farms in different Spanish regions and its possible use in epidemiology studies. Of the 214 samples analyzed, 78.04%, 69.86%, and 62.26% were found to be positive by nested PCR, indirect immunofluorescent antibody test, and optical microscopy of Giemsa-stained smears, respectively. The three techniques were in agreement in 68.6% of the results. The observation that the prevalence of Mediterranean theileriosis estimated using nested PCR alone (70.3%) and that obtained using all three diagnostic techniques together (80.4%) did not significantly differ verifies the utility of this technique in epidemiology studies.

Theileriosis caused by Theileria annulata can be effectively prevented by vaccination with attenuated, cultured schizonts. Although these attenuated vaccines have been applied for a long time, not much is known about the fate of the vaccie strain in the field. Here, two experimental Spanish vaccine strains originating in Cádiz and Cáceres, and one Sudanese strain are studied to address the development of a carrier status and the infectivity for Hyalomma ticks. Moreover, the heterogeneity of the merozoite surface protein, Tams1, was analyzed in search for an attenuation marker. Using the sensitive reverse line blot (RLB) hybridization, the development of a low level carrier status was demonstrated in the Cáceres and Sudanese line vaccinated calves. Although no signal was detected in the Cádiz line vaccinated calves, seroconversion against the schizont stage was observed, as it was in all other calves. The experimental transmission of T. annulata by Hyalomma ticks to naïve calves was unsuccessful for all cell line inoculated calves. Tams1 heterogeneity indicated a clonal selection of parasites during the process of attenuation, but the Tams1 sequence itself has no connection with the attenuation status. In conclusion, a carrier status develops in attenuated schizont culture vaccinated calves, but is not infective for Hyalomma ticks. Based on these data, the risk for spread of the vaccine strains in the field may be very low.