Molecular Prevalence and Risk Factor Assessment of Theileria Spp. in Small Ruminants of Sistan, Southeast of Iran

Theileriosis is a tropical and sub-tropical disease that causes economic losses in livestock. Theileriosis in small ruminants, manifests through a range of clinical signs, including fever, mucoid nasal secretions, anemia, jaundice, lacrimation, enlarged superficial lymph nodes, anorexia, and accelerated weight reduction. In this study, the prevalence of Theileria spp. was determined in asymptomatic small ruminants of the Sistan region located in the southeast of Iran.

The collected samples of apparently healthy sheep (n=48) and goats (n=52), obtained between February 2023 and February 2024, were tested by PCR for theileriosis detection. Two positive PCR products sequenced and assembled sequences deposited in GenBank with PQ227215 and PQ227216 accession numbers. Phylogenetic analysis conducted based on partial 18S rRNA gene amplification.

The prevalence of Theileria spp. in asymptomatic small ruminants was estimated at 32% in the Sistan region in this study. Risk factors were also investigated. A significant relationship was identified between Theileria infection and tick infestation in goats; however, no significant associations were found with other parameters such as species, gender, age, or location.

Theileriosis appears to be endemic among small ruminants in Sistan. Expanding research efforts in the area and investigating potential risk factors to detect various circulating species of Theileria could aid in managing this disease within the region. Conducting larger-scale studies would be beneficial for disease control efforts.