Molecular characterisation of sarcosporidiosis in cattle of Duhok governorate in Kurdistan region of Iraq

Sarcocystis is an intracellular cyst-forming and zoonotic protozoan parasite that infects striated and no-striated muscles of livestock, reptiles, fish, birds and humans with about 220 globally recognised species. This study aimed to identify Sarcocystis species forming microcysts in cattle through a combination of molecular study using PCR amplification of the 18S rRNA gene, gel electrophoresis with sequencing of the obtained nucleotides and histopathological examination. A total of one hundred muscle samples were randomly collected from slaughtered cattle aged from 1 to 2 years of different abattoirs at Duhok province, Iraq. The current study showed that the total infection rate of slaughtered animals with the parasitic infection was 80%. The histopathological findings showed two morphologically distinct Sarcocysis spp. which were thin and thick-walled cysts with finger-like and/or hair-like protrusions. Mild mononuclear infiltration of inflammatory cells, necrosis and muscle degeneration were found around the cysts. Sarcocystis with thin-walled cysts were morphologically regarded as S. cruzi and those with thick-walled cysts were considered as S. homonis. Molecular analysis and sequencing alignment of thin-walled cysts through BLAST-NCBI software confirmed the presence of S. cruzi with 100% similarity to other S. cruzi sequences published in the Genbank database. The results of phylogenetic tree applied in MEGA-X programme placed S. cruzi isolates in the same cluster to other S. cruzi sequences originating from other countries. Sarcocystis cruzi is globally regarded as one of the most common pathogenic species that causes veterinary and economic impact due to persistent keeping of dogs with cattle for protection issues. Therefore, promoting preventive measures and control strategies are essential for breaking the life cycle of the parasite. This is the first morphological and molecular study of Sarcocystis spp. in Duhok province which will provide significant information for monitoring and control of sarcosporidiosis.