Development and validation of a real-time SYBR green PCR method for the detection and differentiation of Babesia and Theileria species (Apicomplexa: Piroplasmida) in hard ticks and cattle blood from Thailand

Tick-borne pathogens, particularly Babesia and Theileria species, are major threats to cattle production, causing economically significant diseases such as babesiosis and theileriosis. In this study, a real-time SYBR Green PCR assay was developed to detect Babesia and Theileria species in hard ticks ( N = 65) and cattle blood samples ( N = 143) from Thailand. Using primers targeting the mitochondrial cytochrome b gene for Babesia and the nuclear 18S rRNA gene for Theileria , the assay measured specific melting temperatures (Tm) for each species. The results showed distinct Tm values for Babesia bigemina (74.38 ± 0.04 °C), Babesia bovis (75.7 ± 0.06 °C), Theileria orientalis (74.61 ± 0.03 °C), Theileria sinensis (75.84 ± 0.03 °C), and Theileria annulata (74.06 ± 0.03 °C). The assay demonstrated high specificity, with a cutoff cycle threshold of < 35 cycles and a minimum detectable concentration of 10 copies/μL. Significant species differences in melting curves were confirmed using Tukey’s HSD test ( p < 0.05). Theileria orientalis was detected in 8.4% of cattle blood samples, while T. sinensis was found in 25.9%, and B. bigemina in 0.7%. Theileria orientalis was also detected in 7.7% of tick samples, T. sinensis in 16.9%, and B. bigemina in 6.1%. The assay returned negative results for all non-target blood and tissue pathogens tested for specificity. This robust, high-throughput assay is highly effective for monitoring Babesia and Theileria infections, facilitating close surveillance and intervention efforts against tick-borne diseases in cattle.