Twenty Years of Equine Piroplasmosis Research: Global Distribution, Molecular Diagnosis, and Phylogeny

Abstract

Equine piroplasmosis (EP), caused by the hemoparasites Theileria equi, Theileria haneyi, and Babesia caballi, is an important tick-borne disease of equines that is prevalent in most parts of the world. Infection may affect animal welfare and has economic impacts related to limitations in horse transport between endemic and non-endemic regions, reduced performance of sport horses and treatment costs. Here, we analyzed the epidemiological, serological, and molecular diagnostic data published in the last 20 years, and all DNA sequences submitted to GenBank database, to describe the current global prevalence of these parasites. We demonstrate that EP is endemic in most parts of the world, and that it is spreading into more temperate climates. We emphasize the importance of using DNA sequencing and genotyping to monitor the spread of parasites, and point to the necessity of further studies to improve genotypic characterization of newly recognized parasite species and strains, and their linkage to virulence.

Characterization of the Rhipicephalus (Boophilus) microplus Sialotranscriptome Profile in Response to Theileria equi Infection

“…Moreover, the worldwide prevalence of T. equi obtained by molecular studies is estimated at 34.6% (95% CI: 34.48–34.76) [ 3 ]. Such consequences of the T. equi infection directly impact the horse performance and paves the way for a source of infection for competent vectors and healthy animals [ 4 , 5 ].…”

First Case of Autochthonous Equine Theileriosis in Austria

“…Equine piroplasmosis (EP) is an OIE-listed (World Organisation for Animal Health) disease ( accessed on 15 January 2020) that affects horses, donkeys, mules, and wild equids such as zebras. Clinical presentation is highly variable, which frequently makes diagnosis difficult [ 1 ]. The disease significantly impairs animal health in countries in which it is endemic, such as tropical and subtropical regions, and some parts of South Africa and South America.…”

“…The disease significantly impairs animal health in countries in which it is endemic, such as tropical and subtropical regions, and some parts of South Africa and South America. In Europe, EP has been described in the UK, the Netherlands, France, Switzerland, Italy, Spain and Portugal (including the Azores), Romania, Serbia, Montenegro, Bosnia and Herzegovina, Greece, Turkey, and Israel; however, not all of these countries are considered endemic areas [ 1 ].…”

“…While both parasites have comparable life cycles, can cause similar clinical signs, and can be transmitted by the same vectors, B. caballi parasitizes exclusively erythrocytes and is transmitted trans-stadially (from one developmental stage to the next) as well as trans-ovarially (from the female adult to the larvae via the eggs) within the tick population, while T. equi is transmitted only trans-stadially (hence its reclassification from Babesia equi [ 3 ]), and parasitizes both erythrocytes and peripheral blood mononuclear cells [ 1 , 4 ]. Babesia caballi infections are transient, while T. equi frequently induces chronic infections, and infected horses are persistent reservoirs for the tick hosts [ 1 , 5 , 6 ]. Due to its longer persistence (among other factors), T. equi is considered to be generally more widespread than B. caballi [ 1 , 7 , 8 ].…”

“…Babesia caballi infections are transient, while T. equi frequently induces chronic infections, and infected horses are persistent reservoirs for the tick hosts [ 1 , 5 , 6 ]. Due to its longer persistence (among other factors), T. equi is considered to be generally more widespread than B. caballi [ 1 , 7 , 8 ].…”