Occurrence and Genetic Diversity of <i>Babesia caballi</i> and <i>Theileria equi</i> in Chilean Thoroughbred Racing Horses

• Main Authors: Reinaldo Torres, Claudio Hurtado, Sandra Pérez-Macchi, Pedro Bittencourt, Carla Freschi, Victoria Valente Califre de Mello, Rosangela Zacarias Machado, Marcos Rogério André, Ananda Müller
• Format: Article
• Language: English
• Published: MDPI AG 2021-06-01
• Series: Pathogens
• Subjects: equine piroplasmosis; babesiosis; theileriosis; ELISA; nested PCR
• Online Access: https://www.mdpi.com/2076-0817/10/6/714

This study aimed to serologically and molecularly survey <i>Babesia caballi</i> and <i>Theileria equi</i> in thoroughbred horses from racecourses in Chile. Additionally, the genetic diversity of the positive samples was assessed. A total of 286 thoroughbred horses from the Santiago and Valparaíso racecourses had their serum samples submitted to an ELISA for <i>B. caballi</i> and <i>T. equi</i>, and 457 samples (from the Santiago, Valparaíso, and Concepción racecourses) were tested with nested PCRs for the <i>B. caballi</i> 48 KDa rhoptry protein (RAP-1) and <i>T. equi</i> 18S rRNA genes. Selected RAP-1 and 18S positive products were sequenced to perform phylogenetic and haplotype analyses. An overall seroprevalence of 35.6% was observed for these Chilean racecourses: 23.7% for <i>T. equi,</i> 8.4% for <i>B. caballi</i>, and 3.5% for both agents. Overall, a 53.6% occurrence by nPCR was detected for the three Chilean racecourses: 44.2% for <i>T. equi</i>, 5.4% for <i>B. caballi</i>, and 3.9% for both agents. Phylogenetic analysis of <i>T. equi</i> and <i>B. caballi</i> showed genetic proximity with sequences previously detected in other countries. Haplotype analysis revealed a low diversity among the Chilean sequences, which may have originated from those reported in Brazil, Israel, or Cuba. <i>Babesia caballi</i> and <i>T. equi</i> were detected for the first time in Chilean thoroughbred horses.