Molecular detection of Theileria species and Babesia caballi from horses in Nigeria

Abstract

Equine piroplasmosis (EP) is an infectious, tick-borne disease caused by the hemoprotozoan parasites, Theileria equi, Babesia caballi, and a recently reported new species, T. haneyi. Infections by these apicomplexan parasites limit performance and cause economic losses for the horse industry. Equine piroplasmosis is widespread in the northern regions of Nigeria, where an increasing portion of the animal population is composed of horses. This disease has remained epidemiologically challenging, especially as the movement of horses increases across Nigeria. In this study, blood samples from 300 horses were collected in three states of northwestern Nigeria. The presence of piroplasms was screened by nested PCR targeting 18S rDNA and positive samples were analyzed using species-specific-nested PCR-targeting genes including ema1 (T. equi), rap1 (B. caballi), and a gene coding a protein of unknown function (T. haneyi). Species-specific-nPCR results demonstrated that the prevalence of T. equi was 13.0% (39/300), B. caballi was 3.3% (10/300) and T. haneyi was 2.7% (8/300). Mixed infections with T. equi and B. caballi was 2.7% (8/300) while T. equi, B. caballi, and T. haneyi multiple infection prevalence was 0.6% (2/300). We used 18S rDNA sequences to determine close relationships between T. equi by phylogenetic analysis and demonstrated that among 57 sequences of Theileria parasites, 28 samples belonged to clade A (49%), 13 samples were found to be clade C (22%), and 16 were clade D (28%). These results demonstrate the genetic diversity of T. equi circulating in horses from Nigeria.

Imidocarb Dipropionate Lacks Efficacy against Theileria haneyi and Fails to Consistently Clear Theileria equi in Horses Co-Infected with T. haneyi

“…However, it has been identified in South Africa, Nigeria, The Gambia, and in horses along the US-Mexico border [ 14 , 16 , 17 , 18 ]. Prevalence surveys in The Gambia, Nigeria, and South Africa have also reported co-infection of horses with T. equi and T. haneyi or triple infection with T. equi , T. haneyi , and B. caballi [ 16 , 17 , 18 ]. Both of these Theileria species cause persistent, asymptomatic infection, and both are capable of superinfection in the presence of humoral immunity to the other [ 15 ].…”

Molecular and Serological Detection of Piroplasms in Horses from Nigeria

“…Recently, a Theileria species 18S rDNA variant was elevated as a distinct species [2]. Recent investigations using phylogenetic analysis of rDNA showed Theileria piroplasm variants from horses in Nigeria, including T. haneyi [21,41].…”

“…Therefore, there is a need for combined high sensitivity molecular and serological studies that enhance the detection of animals exposed to the parasites that cause EP in Nigeria. Only in the last year has the use of molecular tools been reported in Nigeria [ 4 , 21 , 22 ]. Here, we report using the World Organization for Animal Health (OIE) approved cELISA serological tests [ 23 ] combined with molecular detection for T. equi , T. haneyi , and B. caballi to increase our ability to detect horses exposed to pathogens that cause EP.…”

Rapid Detection of Equine Piroplasms Using Multiplex PCR and First Genetic Characterization of Theileria haneyi in Egypt

“…Infection with T. equi and B. caballi can cause severe economic losses in the equine industry due to the cost of treatment, especially for acutely infected horses, which, in the absence of appropriate treatment, can die [2]. It was found that T. haneyi rarely causes clinical signs in field horses [9], even in splenectomized horses experimentally infected with T. haneyi using the intravenous (IV) route [5,10]. Horses infected with T. equi remain persistently infected, while those affected by B. caballi are infected for an extended period [11].…”