Neurotuberculosis in a Holstein-Friesian Calf from the State of Rio Grande do Sul, Brazil

Abstract

Bovine tuberculosis is a chronic granulomatous disease caused by Mycobacterium tuberculosis var bovis. Despite control programs, bovine tuberculosis presents a significant challenge worldwide and it remains a concern in Brazil. Neurotuberculosis is a relatively rare form of the disease in which Mycobacterium reaches the central nervous system, leading to the formation of multiple small granulomas on the meningeal surface. This study reports a case of neurotuberculosis in an 8-month-old Holstein-Friesian calf from the state of Rio Grande do Sul, southern Brazil. The clinical course was chronic, of nearly five months, and clinical signs were mainly neurological, including ataxia, motor incoordination, stiff neck, muscular tremors, and seizures. These clinical signs resulted from granulomatous lesions affecting the central nervous system. Similar granulomas were also present in the lungs, mediastinal and mesenteric lymph nodes, and adrenal glands. Histologically the granulomas were characterized by caseous necrosis associated to inflammatory infiltration of epithelioid macrophages, Langhans multinucleated giant cells, lymphocytes, and plasma cells, proliferation of fibrous tissue, as well as occasional mineralization. Ziehl-Neelsen staining method yielded acid-alcohol resistant bacilli amidst necrotic debris and in the cytoplasm of Langhans cells. Clinic-pathological findings, postmortem and histological examinations, along with Ziehl-Neelsen staining, confirmed the diagnosis of neurotuberculosis in the present case. This report highlights the importance of control measures for tuberculosis, given the debilitating and zoonotic nature of the disease and the lack of effective treatment.