Molecular detection and genotyping of Theileria equi infection within the equine population in Giza, Egypt, using real-time PCR as compared with conventional detection methods.

Abstract

Background: Equine piroplasmosis represents one of the main and serious health problems affecting the equines industry globally, caused by a tick-borne protozoa called Theileria equi and Babesia caballi. Aims: This study aimed to identify and genotype T. equi within the equine population from Giza Governorate, Egypt, by comparing the obtained results using the available diagnostic methods.

Methods: We collected 116 apparently healthy horses from the study area during the first half of 2019 to identify T. equi using real-time PCR (qPCR), targeting the 18S rRNA gene. The results were compared with those from microscopic examination of Giemsa-stained blood smears and conventional PCR. Genotyping of the obtained sequences was also conducted to explore the genetic diversity of the detected T. equi strains.

Results: Through sequencing and phylogenetic analysis, our samples were grouped into clusters corresponding to genotype A and genotype E. Our results demonstrated that the qPCR had the highest sensitivity (100%) followed by conventional PCR (68%) while microscopic examination had the lowest sensitivity (38%). Furthermore, the negative predictive value (NPV) of qPCR was the highest (100%) compared with conventional PCR and microscopical examination (80.49% and 68.04%, respectively) which revealed that negative cases detected by qPCR were certainly correct compared with the other two diagnostic assays.

Conclusion: It is highly recommended to incorporate PCR diagnostic assays alongside microscopic examination to evaluate the epidemiological status of equine piroplasmosis. Also, our study demonstrated that T. equi genotype A and genotype E are circulating among Egyptian horses.