Significance of clinical variables and selected biochemical markers in predicting the outcome of bovine anaplasmosis

Abstract

The present study was aimed at evaluating the usefulness of selected inflammatory and oxidative stress markers in predicting the clinical outcome of cattle infected with Anaplasma (A). marginale. The study population consisted of 39 cattle naturally infected with A. marginale. The presumptive diagnosis of this infection was initially achieved on the basis of case history, microscopy and clinical examination findings, and confirmed using A. marginale-specific PCR assays. The diseased cattle were categorised according to the clinical outcome into survivors (n = 26) and non-survivors (n = 13). For comparison, ten clinically healthy cattle were randomly selected and served as controls. Blood was drawn from all examined animals to measure the respective levels of selected cytokines, acute phase proteins, oxidative stress markers, and antioxidant enzyme levels. We found that the clinical examination alone was not conclusive and should be used in conjunction with other diagnostic methods. Nonetheless, the non-surviving animals showed anorexia, frequent coughing, dyspnoea, bloody faeces, recumbency, pale or icteric mucous membranes, and haemoglobinuria. Biochemically, tumour necrosis factor alpha, interleukin (IL)-1β, IL-6, serum amyloid A, fibrinogen, malondialdehye, superoxide dismutase, and catalase levels were significantly higher in diseased cattle compared with controls, and were higher in non-survivors than survivors (P < 0.05). In contrast, reduced glutathione (G-SH) was significantly lower in non-surviving cattle than survivors and controls. Interestingly, a significant correlation was found between parasitaemia of the diseased cattle and most of the measured biochemical variables, with IL-1β and G-SH showing the highest correlation. Our findings clearly demonstrate that A. marginale infection is associated with marked inflammatory and oxidative stress responses, which are higher in non-surviving cattle compared with survivors. The overall degree of cytokine and anti-oxidative disruption may have an important prognostic value for the disease outcome.