Neospora-like Protozoal Infections Associated with Bovine Abortions

Abstract

Abstract. Eighty bovine fetuses with presumed protozoal infections from a previous 2-year retrospective study were examined by immunohistochemistry using antisera against Neospora caninum. In 66 (83%) of the fetuses, protozoa were found that reacted positively with anti-N. caninum sera. In three (4%) additional fetuses, protozoa identified as Sarcocystis species did not react, and in two fetuses (3%) single protozoal clusters were found only in hematoxylin and eosin-stained slides. A group of 20 fetuses were chosen for further evaluation. They included 14 fetuses from the first group of 80 fetuses plus six additional fetuses that had large numbers of protozoa in the fetal brain. The 20 fetuses were examined immunohistochemically with antisera to N. caninum, Hammondia hammondi, and Toxoplasma gondii. Protozoa from 3/20 fetuses, identified as Sarcocystis species, failed to react with any antisera. In 16/20 fetuses protozoa reacted positively to antisera against N. caninum, and in most cases reacted to H. hammondi, and weakly to one or more of the antisera against T. gondii. Thickwalled protozoal tissue cysts were found in the brain of four of these 16 fetuses by transmissiosn electron microscopy. The cyst wall morphology was comparable to N. caninum. The results suggested that a single protozoal parasite of unknown identity was responsible for most of the bovine abortions. By immunohistochemistry, the unknown protozoon reacted most strongly and consistently to N. caninum antisera, but was antigenically distinct from N. caninum. Ultrastructurally, tissue cysts found in four fetuses most closely resembled Neospora caninum.

Neosporal Abortion in Oklahoma Cattle with Emphasis on the Distribution of Brain Lesions in Aborted Fetuses

“…1,13 Case reports from several geographic regions in the USA have confirmed that the disease is more widespread in dairy cattle, but it also occurs in beef animals. 3,6,8,10,11,14 Transplacental transmission is currently the only known route of infection, but a vertebrate definitive host is suspected. 5 The fetal lesions of bovine neosporosis have been described in previous reports.…”

“…5 The fetal lesions of bovine neosporosis have been described in previous reports. [2][3][4]6,8,[10][11][12]14 It is believed there is a preliminary placentitis from which the organism is distributed through the blood to fetal tissues. In field cases of neosporal abortion, the organism has been identified in brain, spinal cord, striated muscle, liver, kidney, lung, adrenal gland, and adipose tissue, and it is associated with either granulomatous or nonsuppurative inflammation.…”

Association between seropositivity for Neospora caninum and reproductive performance of beef heifers in the Pantanal of Mato Grosso do Sul, Brazil

“…Neosporosis has emerged as an important disease in bovines worldwide and is related to reproductive loss in these animals, causing abortions and neonatal mortality (ANDERSON et al, 1991;BARR et al, 1991;THORNTON;THOMPSON;DUBEY, 1991;WOUDA et al, 1999). Establishing the diagnosis of neosporosis is therefore important, as a step in re-breeding and possibly switching dams according to their history of abortions (DUBEY; SCHARES; ORTEGA-MORA, 2007).…”

Neospora caninum Antigens Recognized by Mouse IgG at Different Stages of Infection Including Recrudescence

“…Neospora caninum (N. caninum) is a recently identified apicomlexan parasite and a major cause of abortion in dairy cattle worldwide [1,8]. At present, immunohistochemistry and the indirect fluorescent antibody test (IFAT) are mainly used for diagnosing neosporosis [8,29].…”