Histopathological Features of Listerial Rhombencephalitis in Dairy Calves in Kazakhstan

Listeriosis is an infectious disease with zoonotic potential and can cause high fatality rates in animals and humans. Although the available evidence demonstrates the significance of post-mortem histological evaluation in the appropriate diagnosis, there is no sufficient evidence addressing histopathological alterations observed in calves clinically suspected of listeriosis. The current study aimed to carry out a post-mortem analysis of the dairy calves with clinical suspicion of listeriosis and determine a condition that contributed to death using histopathological evaluation. The tissue samples were obtained from 16 dairy calves with the age range of one day to one month, which died presumably due to listeriosis on several livestock farms in the Almaty region of Kazakhstan. The calves had symptoms of neurologic dysfunction prior to death. Necropsy and collection of brain histological specimens were performed, followed by procedures of fixation, dehydration, paraffinization, sectioning, staining with hematoxylin, and eosin along with Levaditi’s method, and the microscopic examination. The histopathology findings were consistent with infection by Listeria monocytogenes and localized to the brainstem leading to the diagnosis of listerial rhombencephalitis.