Host and environmental factors as determinants of equine piroplasmosis seroprevalence in Central Spain

Leticia E Bartolomé Del Pino,Aránzazu Meana

doi:10.5424/sjar/2020183-15315

Abstract

Aim of study: To estimate equine piroplasmosis seroprevalence, identify associated risk factors and assess infection recentness.Area of study: Community of Madrid (Central Spain)Material and methods: Sera from 139 horses and 40 donkeys were examined by cELISA to evaluate Babesia caballi and Theileria equi seroprevalences and examine potential risk factors. They included species, gender, age, breed, colour coat, dedication, external parasite treatments, access to pasture, contact with other species, new introduction, tick infestation, farm altitude, land cover, soil type and climatic zone. A bivariate analysis was performed and significant variables were included in a logistic regression model to examine their independent contribution. In positive samples ELISA inhibition percentiles (EIPs) were used to assess whether infections were old or recent.Main results: True seroprevalence (95% CI), adjusted for test sensitivity and specificity was 19% (13-27) for T. equi and 1% (0-3) for B. caballi. In the bivariate analysis, T. equi seroprevalence varied significantly according to horse and farm-level explanatory variables; high seroprevalence groups generally had high EIPs suggesting recent infection. The multivariable analysis revealed that T. equi seroprevalence increased with age, it was higher in police horses compared to sporting, recreational and breeding animals and in those living in lower altitude where planosol soil type was predominant.Research highlights: T. equi seroprevalence in the area was significantly higher than B. caballi seroprevalence and depends on animal management and environmental factors that affect vector abundance and diversity. Identified risk factors must be considered to improve tick and tick-borne disease control and prevention.

Highlights

Equine piroplasmosis (EP) is a tick-borne disease caused by Babesia caballi and Theileria equi that affects horses, mules, donkeys and zebras, transmitted by ticks of the genera Dermacentor, Rhipicehalus and Hyalomma (Scoles & Ueti, 2015)
The overall piroplasma seroprevalence was lower than those reported in other surveys in Spain (Olmeda et al, 2000; García Bocanegra et al, 2013) and this is to a great extent due to the low prevalence of B. caballi found in the present study
The estimated true seroprevalence for T. equi in horses here reported was similar to that indicated by other authors in the Autonomous Community of Madrid (ACM), Spain (Camino et al, 2018, 2020) and Portugal (Ribeiro et al, 2013), higher than those observed in Greece (Kouam et al, 2010) and lower than in studies in Madrid, Castilla-León, Andalucia, Extremadura and Castilla-La Mancha (Montes Cortés et al, 2017), Italy (Bartolomé del Pino et al, 2016) and Israel (Aharonson-Raz et al, 2014)

Summary

Introduction

Equine piroplasmosis (EP) is a tick-borne disease caused by Babesia caballi and Theileria equi that affects horses, mules, donkeys and zebras, transmitted by ticks of the genera Dermacentor, Rhipicehalus and Hyalomma (Scoles & Ueti, 2015). Antibodies are long-lasting, four years for Babesia and possibly lifelong for Theileria (de Waal, 1992). Diagnostics can be performed by stained blood identification of the parasite, serological tests such as complement fixation test, immunofluorescence antibody test (IFAT) and the enzyme-linked immunosorbent assay (ELISA), and the polymerase chain reaction test (PCR) for parasite DNA detection. EP is responsible for important economic losses in the equine sector being a major constraint to the Leticia E. Bartolomé del Pino and Aránzazu Meana international movement of equines (OIE, 2011); in Spain, horse export restrictions have a high economic impact, over 14.5 million euro per year (Camino et al, 2020)

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