도입우의 진드기매개 주혈원충 감염상과 Theileria sergenti의 치료예방에 관한 연구

Studies on the incidence of tick-borne parasites and chemotherpeutic control to Theileria sergenti infections in exotic cattle in Korea

To establish a control program of tick-borne diseases in the exotic cattle, both dairy and beef cattle, which were newly imported and their progeny exposed at the pasture for grazing, an observation on the incidence and prevalence of blood parasites in each region, and the field trials on the chemotherapy for the control of the diseases were carried out. Regional Incidence of Tick-borne blood Parasite: The etiological agents of the tick-borne diseases in Korea were confirmed as Theileria sergenti, Babesia ovata, Anaplasma marginable and Anaplasma centrale, and among them Theileria sergenti was able to be proved as the most important agent throughout the country. On the regional significant distribution of the blood parasites; T. sergenti was observed in the areas of Gyeonggi, Chungnam, Gyeongnam Provinces; T. sergenti and B. ovata were in the areas of Chungbug and Jeonnam Provinces in the plainous mainland; whereas, in the alpine area of the mainland like in Jangsu of Jeonbug Province, T. sergenti, B. ovata and A. centrale were observed, however, in the alpine area like in Daegwalryeong only T. sergenti was observed. On the other hand, in the Island of Jeju Do, T. sergenti, B. ovata and A. marginale were detected. Incidence and Parasitaemias of Theileria sergenti; Cattle grazed in the areas of high density of tick population showed parasitaemia level of 109.9 to 174.7 per thousand of erythrocytes at 4 to 5 weeks after exposure at the pasture and at the same time the animals showed the typical clinical symptoms of theileriosis, while, in the areas of low density of tick population parasitaemias of 31.3 to 40 per thousand of erythrocytes at 5 to 6 weeks after exposure at the pasture were observed and the animals were tolerated without any clinical symptoms of the disease. In the area of Daegwalryeong, the animals showed parasitaemias of 54.4 to 69.2 per thousand of erythroyctes with clinical symptoms at 8 weeks after exposure at the pasture, though the animals in Jeju Island showed parasitaemias of 33.9 to 42.7 per thousand of erythrocytes at 3 to 4 weeks after exposure at the pasure and they showed the symptoms at the same time. In these studies, the areas were divided into two categories according to the population of ticks in the areas; such as, the areas of high density of the tick population in which the cumulative infection rates of animals infected with T. sergenti increased up to 90% and parasitaemias were maintained over 40 per thousand of erythrocytes with clinical symptoms at 4 to 5 weeks after grazing, and the areas of low density of the tick population in which parasitaemias showed below 30 to 40 per thousand of erythrocytes and the cumulative infection rates of 100% up to 5 to 6 weeks after grazing but no clinical symptoms showed. Efficacy of Chemotherapeutics against Theileria sergenti: Efficacy of Pamaquine against the Strains of Seonghwan and Jangsu; The reduction rates of parasites in the animals infected with the strains of Seonghwan and Jangsu were showed 82.5% and 85.1%, respectively, at 1 week after the administration of Pamaquine, however, at 2 weeks postmedication the efficacy against the Seonghwan strain was not significant but that against the Jangsu strain was prolonged. Efficacy of Primaquine against the Strains of Seonghwan and Daegwalryeong; The reduction rates of parasites in the animals infected with the Seonghwan strain were showed 72.3% at 1 week and 73.2% at 2 weeks after the administration of Primaquine, while, those infected with the Daegwalryeong strain showed high therapeutic efficiency of 92.3% at 1 week and 99.6% at 2 weeks after the administration of the drug. Efficacy of Berenil against the Strains of Seonghwan and Jangsu; The efficacy of Berenil against the strains of Seonghwan and Jangsu was good enough to suppress bovine theileriosis in the field; the drug showed the reduction rates of 70.2% at 1 week and 85.1% at 2 weeks against the Seonghwan strain, and of 83.1