A study of hematological changes in sheep naturally infected with Anaplasma spp. and Theileria ovis: Molecular diagnosis

BACKGROUND: Ovine anaplasmosis and theileriosis are importanttick-borne diseases of sheep and goats which are distributedin the tropical and subtropical areas of the world. OBJECTIVES:This study was performed to assess hematologicalstatus in sheep naturally infected with Anaplasma and Theileriaspp. to clarify the pathogenic aspects of various speciesinvolved in ovine anaplasmosis and theileriosis in Ahvaz region.METHODS: 109 sheep were sampled, and blood parasiteinfections were diagnosed by microscopic examination andPCR. The blood samples were also subjected to hematologicassessment. RESULTS: PCR analysis revealed A. ovis infectionin 86.2% of sheep, while mixed infections with A. marginalewere also detected in 53.2% of them. However, Anaplasma inclusionbodies were only observed in 32.1% of the tested animals.T. ovis were found in 88% of the inspected sheep by PCR,and 67.8% of them were detected microscopically, as well. Hematologicassessment showed that mean RBC, PCV, Hb, andMCHC were significantly lower, whereas MCV and RDW werehigher in the animals with mixed infections of Anaplasma withparasitemia and Theileria, compared to the uninfected sheepand groups with single infection or without parasitemia. CONCLUSIONS:In brief, it seems that Anaplasma can be activatedand induce its pathogenesis in the presence of other infectiveagents in the carrier or asympthomatic animals. It can also beconcluded that mixed infections of Anaplasma with parasitemiaand Theileria may induce a regenerative anemia which ismost likely attributable to a combined effect of the two.

Keywords:

Anaplasma , hematology , sheep , Theileria