Detection of tick-borne pathogens in Rhipicephalus bursa ticks collected from the autochthonous Garrano breed of horses in Portugal.

The study looks into the occurrence of various tick-borne diseases in a species of horse, the Garrano, found in the northern Iberian Peninsula. The research specifically targeted Anaplasma, Ehrlichia, Babesia, Theileria, and spotted fever rickettsiae in the ticks found on these horses.

Introduction to Garrano Horses and Ticks

• Garrano horses are a semi-feral breed native to the mountainous regions in the northern part of the Iberian Peninsula.
• Despite being endangered, these horses have been able to survive and even thrive in the wild. They are also selectively bred due to their adaptability to harsh environments.
• The lifestyle of these horses exposes them to numerous tick species throughout the year. Wildlife serves a critical function in the survival of these tick vectors and the transfer of tick-borne pathogens.

Objective of the Study

• Given the vulnerability of Garrano horses to tick exposure, the primary aim of this study was to investigate the occurrence of several tick-borne pathogens such as Anaplasma, Ehrlichia, Babesia, Theileria, and spotted fever rickettsiae.
• The research aimed to increase knowledge on the presence and circulation of these pathogenic agents within the specific population of Garrano horses.

Methods and Findings of the Study

• The study collected and identified 455 ticks from the Garrano horses, all of which were Rhipicephalus bursa species.
• DNA from these specimens were pooled in sets of five for molecular screening. This screening process was vital in identifying the various bacteria and parasites present.
• The PCR results from these pools confirmed the presence of Candidatus Rickettsia barbariae (n = 12 for the ompB gene, n = 11 for the ompA gene, and n = 6 for the gltA gene), Babesia bigemina (n = 1), Babesia caballi (n = 3), Theileria equi (n = 15) and Theileria haneyi (n = 1).
• Notably, the findings demonstrated that Candidatus R. barbariae co-circulates with B. bigemina and T. equi, which are both vectored by R. bursa.
• For the first time, the research also detected T. haneyi among R. bursa ticks feeding on the Garrano horses in Portugal.

Implication of the Study

• The results from this study elucidate the circulation of the emerging rickettsial spotted fever group member, Candidatus R. barbariae, in R. bursa ticks.
• Surveillance studies on tick-borne infections are crucial as they provide significant information that can facilitate the development and implementation of preventive measures and control strategies, thereby ensuring the protection and survival of the Garrano horses.