Veterinary Parasitology 187 (2012) 558–562 Contents lists available at SciVerse ScienceDirect Veterinary Parasitology jou rn al h om epa ge: www.elsevier.com/locate/vetpar Short Communication Demographic and environmental risk factors for infection by Theileria equi in 590 horses in Israel Amir Steinman a,∗ , Tal Zimmerman a , Eyal Klement a , Itamar M. Lensky b , Dalia Berlin a , Yuval Gottlieb a , Gad Baneth a a Koret School of Veterinary Medicine, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, POB 12, Rehovot 76100, Israel b Department of Geography and Environment, Bar-Ilan University, Ramat-Gan 52900, Israel a r t i c l e i n f o Article history: Received 2 November 2011 Received in revised form 4 January 2012 Accepted 10 January 2012 Keywords: Theileria equi Horse Polymerase chain reaction Environmental risk factors Israel a b s t r a c t The prevalence of Theileria equi infection as well as the environmental and demographic risk factors for infection was studied in 590 healthy horses from 46 farms in Israel. The prevalence of T. equi DNA was assessed using a polymerase chain reaction for a segment of the Theileria 18S rRNA gene. The overall prevalence was 26.4% (156/590). There was a significant geographical variation in the prevalence of T. equi infection, ranging from 9.3% (25/270) in the central lowlands to 81.7% (49/60) in the Golan Heights. The prevalence of T. equi infection was found to be significantly associated with management types with more horses with access to pasture being positive. Breed was identified as a risk factor for T. equi infection in a univariate analysis with relatively high infection rates in the Quarter horse and local breeds (41.1% and 36.3% respectively), while ponies and Arabian horses had a relatively low prevalence (10% and 9.1%, respectively). However, since a correlation between geographic location and breed was found, it is difficult to draw definite conclusions regarding this risk factor. Age and gender were not found as risk factors for T. equi infection in this study. The environmental variables that were significantly associated with positivity were relative humidity and minimum land surface temperature at day which both showed negative correlation with T. equi prevalence. In conclusion, Israel was found to be enzootic for T. equi infection, as indicated by the high sub-clinical infection rate, which differed between geographical areas. © 2012 Elsevier B.V. All rights reserved. 1. Introduction Theileriosis is a febrile, tick-borne disease caused by Theileria equi (T. equi). The disease is mainly endemic in tropical and subtropical areas, but regions with a moder- ate climate may be affected as well. Clinical signs may vary from asymptomatic to severe in acute cases with fever, hemolytic anemia, jaundice, hemoglobinuria, and death. Identification of the parasites in blood smears is highly ∗ Corresponding author. Tel.: +972 3 9688534; fax: +972 3 9604079. E-mail address: steinman@agri.huji.ac.il (A. Steinman). diagnostic, but is limited by its low sensitivity (Heim et al., 2007; Rüegg et al., 2007). A variety of serological meth- ods, have been developed mostly for large scale studies and to monitor infections during the latent stage characterized by microscopically undetectable parasitemia (Kouam et al., 2010a). Molecular methods to detect DNA of T. equi and Babesia caballi (B. caballi) in horse blood were introduced already in the early 1990s (Posnett and Ambrosio, 1991; Posnett et al., 1991) and are considered to be sensitive, specific and therefore useful as diagnostic tools. The prevalence and risk factors of equine piroplasmosis which is caused by either T. equi or B. caballi and sometimes by both have been the focus of epidemiological studies 0304-4017/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.vetpar.2012.01.018