NATURAL PREVALENCE OF INFECTION WITH EHRLICHIA (CYTOECETES) PHAGOCYTOPHILA OF IXODES-RICINUS TICKS IN SCOTLAND

Ixodes ricinus nymphs and adults were collected from vegetation and fr om sheep at four sites in Scotland typical of areas endemic for tick-b orne fever in sheep caused by infection with Ehrlichia (Cytoecetes) ph agocytophila (Rickettsiales). The great majority of ticks examined was from woodland sites adjacent to sheep farms where there was a high pr obability of them feeding on roe deer (Capreolus capreolus) in a non-d omestic focus of infestation and infection, Ticks were examined for in fection by five methods, Batches of ticks were examined either by feed ing on susceptible sheep or by feeding on rabbits and then prepared as stabilate which was inoculated into susceptible sheep. The sheep were monitored for clinical signs of tick borne fever. Batches of ticks we re examined by polymerase chain reaction for Ehrlichia phagocytophila. Salivary glands were dissected out and stained by the Feulgen method to detect Ehrlichia masses, and were examined by indirect fluorescent antibody test. Each of the methods detected infection in ticks and the prevalence of infection in nymphs with the various methods ranged fro m >0.25% to 2.0%. Small samples of adults examined by Feulgen staining of salivary glands indicated infection prevalences of 2.1% in males a nd 1.6% in females, It is considered that these low infection prevalen ces may be typical of natural foci of infection where deer could be a major host of ticks and E. phagocytophila. (C) 1998 Elsevier Science B .V. All rights reserved.