Factors associated to Theileria equi in equids of two microregions from Rio de Janeiro, Brazil

Tiago Marques dos Santos,Joice Aparecida Rezende Vilela,Carlos Luiz Massard,Huarrisson Azevedo Santos,Fernando Queiroz de Almeida,Cristiane Divan Baldani,Marcus Sandes Pires,Erica Cristina Rocha Roier,Rosangela Zacarias Machado,Larissa Martins de Brito Moraes

doi:10.1590/s1984-29612011000300011

Abstract

Serum samples from 714 equids of Itaguaí and Serrana microregions, Rio de Janeiro, southeastern Brazil, were examined by indirect fluorescent antibody test (titer 1:80) for Theileria equi. The prevalence in the microregions and factors associated with seropositivity were evaluated and the prevalence ratio (PR) calculated. The overall prevalence of T. equi infection was 81.09% (n = 579), with higher prevalence (p < 0.05) in the Itaguaí (85.43%) when compared to Serrana microregion (76.92%). The geographic area, altitude, farming condition and area of origin of equids were associated (p < 0.05) with seropositivity for T. equi. Equids reared in the Itaguaí microregion (PR = 1.11, p = 0.003) and at altitudes below 500 m (PR = 1.10; p = 0,014) were more likely to be seropositive for T. equi. Furthermore, when equids were born in the farm (PR = 1.10, p = 0.008) and reared with poor farming conditions (PR = 1.13, p = 0.018) they were more likely to be exposed to T. equi. The main ticks found on equids were Amblyomma cajennense and Dermacentor (Anocentor) nitens. The microregions studied are endemic areas for equine theileriosis and there exists enzootic stability for T. equi. Only factors related to the collection area of serum samples influenced the seropositivity of equids for T. equi in that region.

Highlights

Equine theileriosis, known as equine piroplasmosis, is a disease caused by Theileria equi, an intraerythrocytic parasite that infects equids
The prevalence of T. equi infection found in this study is corroborated by previous studies showing that equine theileriosis is endemic in the municipalities of the metropolitan mesoregion of Rio de Janeiro (PFEIFER BARBOSA et al, 1995; BITTENCOURT; MASSARD, 1997; BOTTEON et al, 2002; SANTOS et al, 2009)
In these studies the prevalence of T. equi infection ranged from 73.6 to 100%, which can be explained by differences in the number of equids examined and serological test used for diagnosis

Summary

Introduction

Known as equine piroplasmosis, is a disease caused by Theileria equi, an intraerythrocytic parasite that infects equids. This agent is biologically transmitted by ixodid ticks (THOMPSON, 1969). Equine theileriosis has a worldwide distribution and is endemic in most tropical and subtropical areas as well as in some temperate regions (DE WAAL, 1992). This distribution is closely related to areas of higher concentration of vector ticks (FRIEDHOFF, 1988). The present study aimed to determine the prevalence of T. equi in equids and whether there exists enzootic stability for T. equi in the microregions studied and to identify factors associated with seropositivity in equids

Materials and Methods

Results

Discussion