[The occurrence of Babesia divergens in the Freiburg i. Br. district and piroplasmosis prevention trials in cattle].

The occurrence of Babesia divergens in the Freiburg i. Br. district is reported. By interviewing farmers and by serological investigations, three valleys where located in which bovine piroplasmosis occurs since many years. Main objective of this study was to strategically control the vector ticks, Ixodes ricinus with the synthetic pyrethroid flumethrin, in order to prevent clinical piroplasmosis after turnout to pastures in spring, without interfering with protective immunity against Babesia divergens. A total of 200 cattle were used for trials in the period 1990-92. Three pour-on treatments of fortnightly intervals provided best results. Only 4.3% of 163 treated cattle contracted piroplasmosis, in contrast to 19% of 37 untreated cattle. All cattle were sero-negative at the time of turnout. At the end of pasture periods 1990 and 1991 82.4 and 79.6% respectively of treated cattle were sero-positive.