Morpho-molecular characterization of Trypanosoma evansi in sheep

Trypanosoma evansi is a protozoan parasite that causes trypanosomiasis, referred to as ‟surra." It affects a wide variety of both wild and domesticated species on many continents. The primary host species differ geographically; however, camelids, equine, buffalo, and farm animals are at risk of infection. In vector-borne sickness, numerous species of blood-consuming flies, along with Tabanids and Stomoxys, are involved in transporting pathogens from one animal to another, acting as mechanical vectors.

This study was established to evaluate the prevalence of T. evansi in sheep in Baghdad and investigate the impact of age and sex on the infection rate.

A total of 200 blood samples were obtained from October 2023 to March 2024. These samples were examined using Giemsa stain under a light microscope, and 40 positive samples were selected for further investigation using conventional polymerase chain reaction (PCR).

The results showed an infection rate of 20%, with significant differences observed between male and female sheep. Younger sheep were found to be significantly more affected than older ones. Ten PCR-detected samples were randomly selected for DNA molecular analysis to obtain ITS-1 gene nucleotide sequences. The PCR product exhibited a band size of 1,264 bp, and the sequences were deposited in the National Center for Biotechnology Information under the following code numbers: PP930358.1, PP930353.1, PP930350.1, PP930357.1, PP930356.1, PP930351.1, PP930359.1, PP930352.1, PP930354.1, and PP930355.1.

The current study results indicate that T. evansi occurs and circulates in sheep and confirm that the molecular approach for detecting DNA of Trypanosoma species by the use of ITS1 makes it a highly dependable assay for species recognition of this parasite.