1Department of Pathobiology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran
2Department of Clinical Sciences, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran
Studies on the pathogenesis of Babesia ovis infection following blood transfusion of infected blood to sheep with intact spleen and splenectomised sheep showed that all animals developed fever concurrent with a parasitaemia that were occurred within 2-4 days post-inoculation (dpi), clinical signs of disease were severe and included varying degrees of anorexia, listlessness, anaemia, moderate jaundice and haemoglobinuria. In intact animals, the hyperthermia returned to normal on the fourth day after the peak pyrexia and parasitaemia was eliminated within the course of the disease in four cases. However, other cases which had severe clinical signs of the disease were died. The parasitaemia reached a maximum of 7% in splenectomised sheep 7-8 dpi; in animals with intact spleen, the parasitaemia was much lower and reached to a maximum of 1%. In both of the infected groups, the red cell counts, haematocrit and haemoglobin concentration fell soon after the appearance of parasitaemia, reaching their lowest levels simultaneously with the peak parasitaemia. The total leukocyte counts were significantly decreased. The total serum bilirubin levels of the infected group rose above the normal and peaked on 14-16 dpi; the rise in AST, BUN and creatinine levels were slight. The kidneys and lungs were the organs most severely affected by experimental infection with B. ovis. Acute alveolar oedema and infiltration of neutrophils and macrophages in interstitial tissue were present, acute diffuse proliferative glomerulitis, congestion and stasis in glomerular capillaries and acute tubular necrosis were also present.