Prophylactic treatment with flumethrin, a pyrethroid (Bayticol？, Bayer), against Anaplasma phagocytophilum infection in lambs

In the present study, we investigated if frequent pour-on applications of pyrethroids would reduce tick infestion rate and seroprevalence of A. phagocytophilum infection in sheep. Forty lambs, one month old, of the Norwegian White Sheep breed were used. The lambs belonged to the experimental sheep flock at the Department of Production Animal Clinical Sciences. None of the lambs had been on I. ricinus infested pasture before turnout (day 0). All lambs were twins and twenty lambs were treated with a pour-on pyrethroid (Bayticol？, Bayer A/S, DK-2300) with a dose of 5？ml on days 0, 14, 28, 42, 56, 70, 84, 98, 112 and 128. Twenty lambs were untreated controls. The lambs were collected every fourteen days on pasture for treatment. In addition, the lambs were examined for ticks, blood sampled, weighed, and rectal temperature was recorded.A significant reduction in tick infestion rate was detected on treated lambs. However, the present results indicate that frequent acaricide treatment does not reduce the seroprevalence to A. phagocytophilum on tick-infested pasture.