Haematological and histological findings in experimental Newcastle disease
2001
Galindo-Muniz, F. | Calderon, N.L. | Charles, M.N. | Tellez, I.G. (National Autonomous Univ., Mexico City (Mexico). Dept. of Avian Production) | Fortoul, T.I.
To obtain more information about pathogenesis of haemorrhages in Newcastle disease, blood cells counts with special emphasis on thrombocytes were performed in 25 specific pathogen-free chickens experimentally infected by ocular instillation of 10**6 embryo-lethal doses 50 % of a velogenic viscerotropic strain of Newcastle disease virus. Birds were killed at 24 h post infection, followed by 12 h intervals. In the bone marrow early necrosis of haematopoietic islands was noted at 48 hpi, an increase in heterophil and a decrease in monocyte and lymphocyte counts was observed; thromboblasts showed basophilia, nuclear and cytoplasmic vacuolation. Swelling and vacuolation of capillary endothelial cells were evident, mainly in the lungs. We consider thrombocytopenia and endothelial damage to be the main causes of haemorrhages in this animal model. A significant reduction at 72 h post infection of thrombocyte counts and multifocal necrosis of bone marrow cells was observed. Thrombocytopenia was the end result of a direct viral damage to bone marrow precursor cells.
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