Epidemiology and genetic diversity of Theileria equi and Babesia caballi in Mongolian horses

Equine piroplasmosis is a tick-borne disease caused by Theileria equi and Babesia caballi in horses. Because of its impact on horse industry, control of this disease is crucial for endemic countries. The control of equine piroplasmosis may be influenced by the genotypic diversity of T. equi and B. caballi. Mongolia, a country with a thriving livestock industry, is endemic for T. equi and B. caballi. However, nationwide epidemiological surveys have not been conducted to determine the current status of infections and genetic diversity of these two parasite species. Therefore, the objective of this research was to investigate the infection rates and genotypes of T. equi and B. caballi in horses across Mongolia. Blood samples were collected from 1353 horses in 15 of Mongolia's 21 provinces, and their DNAs were analyzed with T. equi- and B. caballi-specific PCR assays. Additionally, blood smears were prepared from 251 horses, stained with Giemsa, and examined under a light microscope to identify T. equi and B. caballi. The microscopy revealed that 30 (11.9%) and 4 (1.6%) of the 251 horses were positive for T. equi and B. caballi, respectively. By contrast, PCR assays detected the T. equi and B. caballi in 1058 (78.2%) and 62 (4.6%) horses, respectively. Phylogenetic analysis of 18S rRNA sequences from 42 randomly selected T. equi-positive DNA samples detected the genotypes A and E. On the other hand, the rap-1 sequences from 19 randomly selected B. caballi-positive DNA samples occurred in clades representing the genotypes A and B1, as well as in a distinct clade closely related to the genotype A. Our findings confirm the widespread occurrence of T. equi and B. caballi infections in Mongolian horses, highlighting the need for a comprehensive control approach.

Serosurvey for equine piroplasms in horses and donkeys from North-Western Nigeria using IFAT and ELISA

Equine piroplasmosis is caused by apicomplexan parasites, namely, Babesia caballi and Theileria equi, which are transmitted to equids principally through ticks. To ascertain the exposure of equines to agents of equine piroplasms, we tested serum samples collected from horses (n = 272) and donkeys (n = 170) in North-Western Nigeria for the presence of antibodies against B. caballi and T. equi using IFAT and ELISA. The seroprevalence of T. equi in the horses determined using IFAT and ELISA was 48.89% and 45.96%, respectively, while for B. caballi, it was 6.3% and 0.4%, respectively. For T. equi, the seroprevalence based on IFAT and ELISA results in donkeys was 14.1% and 2.9%, respectively, while for B. caballi, the seroprevalence was 2.4% and 0.6%, respectively, for ELISA and IFAT. Mixed infection detected in the horses using IFAT and ELISA was 5.5% and 0.4%, respectively, while no mixed infection was observed in the donkeys. The seroprevalence of T. equi was significantly (P < .0001) higher than that of B. caballi in both horses and donkeys. Comparatively, the IFAT detected a greater number of piroplasm seropositive animals than ELISA, indicating a difference in their diagnostic accuracy. Findings from this study confirm the existence of equine piroplasms in both horses and donkeys in North-Western Nigeria and highlights the need for robust and effective control measures against the disease.

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

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.