Hemoparasitism, humoral immunodeficiency, and an IgG1 fragment in a cow.

An adult cow with nonregenerative anemia was found to be infected with Eperythrozoon wenyoni and Trypanosoma theileri. Further laboratory testing revealed hypoalbuminemia, hypogammaglobulinemia, decreased numbers of circulating B lymphocytes, and presence of a serum immunoglobulin G1 fragment. Reduced B-lymphocyte regions in lymphoid tissue, evidence of chronic nephritis, and infection with Fasciola hepatica and Sarcocystis spp were found at necropsy. The cause of the acquired humoral immunodeficiency and the serum immunoglobulin G1 fragment was undetermined.