Sarcocystis Cymruensis in the Brown Rat (Rattus Norvegicus) from an Urban District in Kuwait: Detailed Morphologic and Molecular Characterization

Abstract

Purpose

The objective of the study was to establish the prevalence of Sarcocystis (Apicomplexa, Sarcocystidae) in brown rats from Jleeb Al-Shuyoukh, Kuwait, and to describe detected parasites using morphological and DNA analysis methods.

Methods

Ninety-eight brown rats (Rattus norvegicus) were examined for Sarcocystis spp. Obtained sarcocysts were investigated using light microscopy and electron microscopy. The detected Sarcocystis species was characterised at nuclear 18S and 28S ribosomal RNA (rRNA), internal transcribed spacers 1 and 2, (ITS1 and ITS2), mitochondrial cytochrome c oxidase subunit I (cox1) and cytochrome b (cytb), and apicoplast RNA polymerase beta subunit (rpoB).

Results

Sarcocysts were found in thigh muscles of 13.3% of the animals examined, while no oocysts/sporocysts were detected in faecal samples. Under a light microscope, sarcocysts were spindle-shaped, 850–3152 × 73–125 μm (1781 ± 763 × 99 ± 15 μm) in size and had thin (up to 0.9 μm) and apparently smooth cyst wall. By transmission electron microscopy, sarcocyst wall was 0.7–1.1 μm in thickness with numerous osmiophilic bleb-like protrusions. Based on DNA sequencing the sarcocysts examined were identified as S. cymruensis. Notably, ITS2 and rpoB sequences of S. cymruensis were obtained for the first time. No intraspecific variation was detected comparing 28S rRNA, ITS1, cox1 and cytb sequences of S. cymruensis isolated from Kuwait, Grenada and China. According to phylogenetic analysis, S. cymruensis was most closely related to S. muris, S. myodes and S. ratti using rodents as their intermediate hosts and cats as their identified or predatory mammals as their presumed definitive hosts.

Conclusion

We present the first report of S. cymruensis in Kuwait and in Persian Gulf area. The study shed light on the usefulness of different genetic loci for the characterization of Sarcocystis spp. from rodents.