Vol.3, No.9, 501-503 (2013) Open Journal of Preventive Medicine http://dx.doi.org/10.4236/ojpm.2013.39067 Preliminary study of natural reservoirs as sentinels of Anaplasma phagocytophilum and Ehrlichia chaffeensis in Soria, northern Spain Lourdes Lledó 1* , Consuelo Giménez-Pardo 1 , José Luis Serrano 2 1 Departamento de Biomedicina y Biotecnología, Universidad Alcalá, Alcalá de Henares, Spain; * Corresponding Author: lourdes.lledo@uah.es 2 Consejería de Sanidad y Bienestar Social de la Junta de Castilla y León, Soria, Spain Received 29 September 2013; revised 30 October 2013; accepted 9 November 2013 Copyright © 2013 Lourdes Lledó et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. ABSTRACT The serum of foxes and red deer from the Prov- ince of Soria (northern Spain) was screened in indirect immunofluorescence assays to deter- mine whether these animals could be used as sentinels of the tick-borne pathogens Anaplas- ma phagocytophilum and Ehrlichia chaffeensis. The results suggest that foxes and red deer would not make good sentinels in epidemiol- ogical studies on E. chaffeensis in this region, although red deer could be used as such for the study of A. phagocytophilum transmission. Keywords: Anaplasma phagocytophilum; Ehrlichia chaffeensis; Foxes; Red Deer; Sentinels; Spain 1. INTRODUCTION Ehrlichia chaffeensis and Anaplasma phagocytophi- lum are the causal agents of severe emerging and re- emerging human diseases [1]. Both are transmitted through the bite of an infected tick. In Europe, the pri- mary 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 Pro- vince 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. 2. MATERIAL AND METHODS 2.1. Study Area The Province of Soria is located in northern Spain (central point 41˚25'0"N, 2˚28'0"W; altitude range 1100 - 1650 m). It has a continental climate with cold winters and mild summers. The region has extensive forested areas and high shrubland [3]. 2.2. Collection of Serum Samples All the serum samples used in this work—30 from wild red deer and 30 from wild foxes—came from our group’s frozen (−20˚C) serum collection. 2.3. Serological Assays Indirect immunofluorescence assays (IFA) were per- formed to detect antibodies to A. phagocytophilum and E. chaffeensis in the tested serum samples according to Santos et al. [4] and Brouqui et al. [5]. Samples were diluted 1:40 in PBS and incubated on slides prepared with HL-60 cells infected with A. phagocytophilum (prepared with Arkansas strain) or DH82 cells infected with E. chaffeensis (prepared with Webster strain) (both types of slides were kindly supplied by R. Sousa and A.S. Santos of the Centro de Estudos de Vectores e Doenças Infecciosas, Instituto Nacional de Saúde Dr. Ricardo Jorge, Portugal). The fluorescein-labelled conjugate was adapted according to the animal species studied (Sigma, St Louis, MO). Results were interpreted as positive when IgG titres of ≥40 were recorded. All positive samples were serially diluted to determine the endpoint titre, which was expressed as the reciprocal of the serum dilu- tion. 2.4. Tick Counts The number of different ticks on each animal from which serum was extracted was recorded in a database at the time of serum preparation. Ticks were enumerated Copyright © 2013 SciRes. OPEN ACCESS