Contents lists available at ScienceDirect Veterinary Parasitology: Regional Studies and Reports journal homepage: www.elsevier.com/locate/vprsr Original Article Environmental factors associated with Dictyocaulus viviparus and Fasciola hepatica prevalence in dairy herds from Costa Rica A.E. Jiménez-Rocha a,⁎ , S. Argüello-Vargas b , J.J. Romero-Zuñiga c , J.A. Sequeira-Avalos d , G. Dolz c , V. Montenegro-Hidalgo a , T. Schnieder e† a Laboratorio de Parasitología, Escuela de Medicina Veterinaria, Universidad Nacional, Costa Rica, P.O. Box 86-3000, Heredia, Costa Rica b Posgrado Regional en Ciencias Veterinarias Tropicales, Universidad Nacional, Costa Rica, P.O. Box 86-3000, Heredia, Costa Rica c Programa de Investigación en Medicina Poblacional, Escuela de Medicina Veterinaria, Universidad Nacional, Costa Rica, P.O. Box 86-3000, Heredia, Costa Rica d Cooperativa de Productores de Leche Dos Pinos, RL. Alajuela, Costa Rica, P.O. Box, 179-4060, Alajuela, Costa Rica e† Institute for Parasitology, University of Veterinary Medicine Hannover, Hannover, Germany ARTICLE INFO Keywords: Prevalence Milk Dictyocaulus viviparus Fasciola hepatica ABSTRACT Dictyocaulosis and fasciolosis are parasitic diseases that cause considerable economic losses for owners of farm animals worldwide, with special relevance on fasciolosis because it is an emerging zoonosis. Indirect diagnosis of these diseases through analyses of bulk milk tank samples has allowed carrying out large-scale prevalence studies, while the use of geographical information systems has helped to visualize and determine those variables that affect distribution of these pathogens. This study is intended to describe the spatial distribution of Dictyocaulus viviparus and Fasciola hepatica in dairy herds from Costa Rica, as well as their associated environ- mental factors. Bulk milk tank samples from 526 dairy herds in the three most important dairy regions of Costa Rica were analyzed using enzyme immunoassays. Results from the farms were subjected to spatial analyses using Holdridge's life zones, relief and soil type environmental layers. Of the total bulk milk tank samples analyzed, 3.8% (n = 20) and 3.6% (n = 19) were positive for D. viviparus and F. hepatica, respectively. Moran's I analysis revealed the existence of potential cluster (Moran's I = 1.789, z = 12.726 p < 0.05) for D. viviparus. Consequently, Getis-Ord General G analysis showed that the spatial distribution of positive farms in the dataset was clustered (Observed General G = 0.015, variance = 0.000001, z = 12.823, p < 0.05). No significant po- sitive spatial autocorrelation (Moran's I = 0.038, z = 0.286, p > 0.0.5) was observed for F. hepatica. Furthermore, a significant difference was detected in the spatial locations of both parasites (latitude p < 0.05, longitude p < 0.05), and about the spatial distribution of both D. viviparus negative and positive farms (latitude p < 0.05, longitude p < 0.05), as well as in F. hepatica negative and positive farms regarding on latitude (p < 0.05), but not on longitude (p > 0.05). In the case of environmental factors, significant differences were found for D. viviparus and F. hepatica with respect to types of soil, precipitation, altitudinal belts, life zones, biotemperature, and elevation. 1. Introduction Bovine dictyocaulosis and fasciolosis are parasitic diseases that cause considerable economic losses in bovine herds (Wapenaar, 2011; Dank et al., 2015; Radfar et al., 2015; Rojas, 2015), and are caused by the Dictyocaulus viviparus nematode and the Fasciola hepatica digenea trematode; both parasites affect a wide range of domestic and wild animals (Issia et al., 2009; Dracz and Lima, 2014; Pyziel et al., 2015). Additionally, fasciolosis is well known as an emerging zoonotic disease (Olsen et al., 2015). There are only a few reports on the economic losses caused by dictyocaulosis, estimations made in the United Kingdom in 2007, based on two dairy herds, indicate an average loss of US $22,852.60 per farm (Holzhauer et al., 2011). On the other hand, in Costa Rica (2015), an outbreak of dictyocaulosis in 28 cows caused losses in milk production close to US $16,225.00 (unpublished data). Regarding fasciolosis, Rojas (2015) estimated annual economic losses for US $67,313.00 from vis- cera confiscations in class A slaughterhouses in Costa Rica. These losses are the result of milk and weight reduction, developmental delays and fertility-related problems, as well as the discarding of a great amount of livers affected in slaughterhouses (Das Chagas et al., 2011; Howell et al., 2015). http://dx.doi.org/10.1016/j.vprsr.2017.06.006 Received 26 September 2016; Received in revised form 31 May 2017; Accepted 13 June 2017 ⁎ Corresponding author. E-mail addresses: ana.jimenez.rocha@una.cr, anajimenez@racsa.co.cr (A.E. Jiménez-Rocha). Veterinary Parasitology: Regional Studies and Reports 9 (2017) 115–121 Available online 15 June 2017 2405-9390/ © 2017 Elsevier B.V. All rights reserved. MARK