A likely case of Theileriosis in cattle in Colombia. First report

Bovine theileriosis is a tick-borne disease caused by protozoa of the genus Theileria and may affect different ruminant species, mainly cattle among domesticated species. The disease occurs mainly in tropical and subtropical regions where climate and environmental conditions favor the development of their vectors. The clinical signs vary according to the infecting species. This study aimed to characterize clinically and present the first report of Theileriosis in Holstein and Simmental cows in Colombia. Two 22-month-old pregnant heifers were referred to the Large Animal Clinic at the National University of Colombia with a history of depression, pigmenturia, and dark feces. The main clinical signs on clinical examination were recumbency, severe dehydration (10-12%), icteric mucous membranes, and weak pulse. The blood cell count revealed severe anemia, hypoproteinemia, and lymphopenia; microscopic alterations in red cells, such as structures compatible with Theileria spp., were observed in lymphocytes and red cells. Increased levels of AST, GGT, urea, chloride, and sodium were observed, and the blood gases revealed metabolic acidosis; ventricular tachycardia was observed in one heifer. The anemia and the morphological alterations could be due to the Theileria in the erythrocytes, which increases their elimination rate along with oxidative changes or immune-mediated mechanisms. The observed lymphopenia could be attributed to the microorganisms within the cells that favor cell destruction. An increase in the hepatic enzyme levels might have resulted from anemia and dehydration that causes poor blood perfusion of the liver. The observed metabolic acidosis and hyperlactatemia were associated with inadequate tissue perfusion. In conclusion, this is a likely outbreak of Theileriosis in Holstein and Simmental heifers in Colombia.