Study on acute-phase protein changes and their diagnostic values in malignant ovine theileriosis

This study was conducted to assess the pattern of changes and the relative value of acute-phase proteins (APPs) including haptoglobin (Hp), serum amyloid A (SAA), ceruloplasmin and fibrinogen in sheep infected with Theileria lestoquardi. The diseased group comprised 50 sheep, naturally infected with T. lestoquardi, and were divided into three subgroups with different parasitaemia rates (<2%, 2–4% and >4%). As a control group, ten uninfected sheep were also sampled. Blood samples were collected, and all measurements were done using validated methods. There were significant differences in red blood cells (RBC), packed cell volume (PCV), haemoglobin (Hb) and concentrations of Hp, SAA, ceruloplasmin and fibrinogen between healthy sheep and those infected with T. lestoquardi with different parasitaemia rates (P < 0.05). As the parasitaemia rate increased, a significant decrease was observed in RBCs, PCV and Hb. In contrast, with an increase in the parasitaemia rate, a significant increase in the mean corpuscular volume, Hp, SAA, ceruloplasmin and fibrinogen was evident. The optimal cutoff point was set by the receiver operating characteristics method to >57.15 μg/ml for SAA, >0.42 g/l for Hp, >0.27 g/l for ceruloplasmin and >3.91 g/l for fibrinogen with corresponding 0.89% sensitivity and 0.98% specificity for SAA, 0.88% sensitivity and 0.65% specificity for Hp, 0.55% sensitivity and 0.96% specificity for ceruloplasmin and 0.65% sensitivity and 0.96% specificity for fibrinogen. In conclusion, measuring SAA with the highest sensitivity, specificity and the area under the curve (AUC) compared to the other APPs is a suitable indicator of inflammatory reactions in Iranian fat-tailed sheep infected with T. lestoquardi.