Field evidence that roe deer (<e1>Capreolus capreolus</e1>) are a natural host for <e1>Ehrlichia phagocytophila</e1>

Samples of blood, spleen and legs from 112 culled roe deer (<e1>Capreolus capreolus</e1>) were collected from nine sites widespread in the United Kingdom. The prevalence of infection with <e1>Ehrlichia phagocytophila</e1> was determined by serology and polymerase chain reaction. Means of 58% of 102 plasma or serum samples were seroreactive by IFA, 38% of 84 blood samples and 29% of 82 spleen samples were positive by PCR. Ticks on legs of 71 roe deer were <e1>Ixodes ricinus</e1> larvae, nymphs and adults and 83% of legs were infested. Numbers of ticks corresponded positively to the percentage of samples positive for <e1>E. phagocytophila</e1> by serology and PCR for different sampling sites. <e1>Ixodes ricinus</e1> nymphs collected from the vegetation at one site with infected deer were analysed for infection with <e1>E. phagocytophila</e1> by examination of Feulgen stained salivary glands. Of 135 nymphs 5% were infected. These results confirm that roe deer are commonly parasitized by both <e1>E. phagocytophila</e1> and its vector tick in such a way that it is likely to be an important natural mammalian reservoir of <e1>E. phagocytophila</e1>.