Ehrlichia chaffeensis and Anaplasma phagocytophilum are the causal agents of severe emerging and reemerging human diseases [1]. Both are transmitted through the bite of an infected tick. In Europe, the primary vector is Ixodes ricinus, for which red deer (Cervus elaphus), foxes (Vulpes vulpes), cattle, sheep, goats and horses act as reservoirs [2]. In Spain, little is known about the epidemiology of these diseases. The present work reports a preliminary study, undertaken in the Province of Soria, to record the prevalence of the above pathogens in foxes and red deer, and to determine the value of these animals as sentinel species.

None of the fox serum samples examined was positive for E. chaffeensis, while three were positive for A. phagocytophilum. All the red deer serum samples were positive for A. phagocytophilum but negative for E. chaffeensis.

A total of 109 ticks were obtained from the red deer: 37 males (33.94%), 56 females (51.37%) and 11 nymphs (10.09%). The most common species identified was Ixodes ricinus, with 35 males (41.17%), 50 females (58.82%), followed by Haemaphysalis punctata with 1 male (20%) and 4 females (80%), and Rhipicephalus bursa with 1 male (33.33%) and 2 females (66.66%). As expected, most of the ticks found were adults (93 [85.32%]). The other work in the study area reported the same tick species on the same hosts [3].

Some 20% of the foxes were parasitised by ticks. The most common species identified (always as adults) were Rhipicephalus sanguineus (50%), Ixodes canisuga (16.6%), Ixodes ricinus (16.6%) and Ixodes hexagonus (16.6%). These species are similar to those recorded on foxes from Thuringia (Germany) [7], and the same as those recorded in foxes in eastern Spain [8] and the Spanish south [9]. Dermacentor variabilis and species of Amblyoma are known to act as vectors of A. phagocytophilum and Ehrlichia spp., but whether other ticks do so is unknown. The present results for the red deer suggest studies are needed to identify the role of other tick species in A. phagocytophilum transmission.

E. chaffeensis is the causal agent of human monocytotropic ehrlichiosis, and foxes are potential reservoirs for this bacterium [10]. A. phagocytophilum is the causal agent of monocytic anaplasmosis, and this pathogen has been confirmed in red deer in Slovakia [11], as well as in sheep, ticks and foxes in Hungary [12]. In Spain, it has been detected serologically and by PCR (in both the north and south) in ticks, roe deer, and cattle [13,14].

Since Ehrlichia and Anaplasma species can cause human disease [15-18], the prevalence of these pathogens in the study area, where contact between wild animals and people through outdoor activities and work, should be monitored. The present results suggest that foxes and red deer would not make good sentinels in epidemiological studies on E. chaffeensis in the study region, although red deer could be used as such for the study of A. phagocytophilum transmission. Red deer would seem to be involved in the natural cycle of this pathogen in this province.

We thank Drs. Rita Sousa and Ana Sofía Santos (Centro de Estudos de Vectores e Doenças Infecciosas, Instituto Nacional de Saúde Dr. Ricardo Jorge, Portugal) for providing the antigen slides for IFA.