Morphological Findings in Bovine Cerebral Theileriosis (BCT)

Abstract

Summary Cattle (n = 29) from Kenya with clinical signs of Turning Sickness were subjected to gross mortem findings, post mortem smears and histological examination. As Theileria schizonts were seen in smears from the brain, the disease was diagnosed as Bovine Cerebral Theileriosis (BCT). As there are other infections causing Turning Sickness and as the observed occurrence of Theileria schizonts is rare in smears and histological slides in some instances, diagnosis of BCT must be based on morphological examination of the central nervous system. Intravenous accumulations of lymphoblasts with and without schizonts, venous thrombi, effects of venous alterations, and perivascular lymphocytic infiltration were regular and characteristic findings in the central nervous system in BCT. The Theileria species which causes BCT are discussed as well as the possible pathogenesis of intravasal lymphoblastic accumulations and venous thrombi within the central nervous system. Zusammenfassung Morphologische Befunde bei der bovinen zerebralen Theileriose (BCT) Rinder (n = 29) aus Kenya mit klinischen Symptomen einer Turning Sickness wurden seziert, Organabstriche und Proben zur histologischen Untersuchung wurden entnommen. Der Nachweis von Theilerienschizonten in den Hirnausstrichen führte zur Diagnose der bovinen zerebralen Theileriose (BCT). Da auch andere Erreger Symptome der Turning Sickness hervorrufen können und der Nachweis von Theilerienschizonten manchmal sowohl am Ausstrich als auch im histologischen Präparat nur unzureichend gelingt, muß die Diagnose BCT mit morphologischen Untersuchungen des Zentralnervensystems abgesichert werden. Intravenöse Ansammlungen von Lymphoblasten mit oder ohne intrazytoplasmatische Schizonten, venöse Thromben und die Folgen der Venenalterationen sind zusammen mit perivaskulären lymphozytären Infiltraten im ZNS regelmäßige und charakteristische Befunde. Die Theilerienspezies, die BCT auslöst, wird ebenso diskutiert wie die Pathogenese der Lymphoblastenansammlungen und Thromben in den Venen des ZNS.

“Ormilo disease” a disorder of zebu cattle in Tanzania: bovine cerebral theileriosis or new protozoan disease?

“…Macroscopical and histological lesions resemble those reported by other authors in BCT caused by Theileria species (Giles et al1978;Bader et al 1986;Lawrence et al 2004), and particularly the accumulation of parasitized lymphoid cells in the cerebral and meningeal blood vessels represents the pathognomonic feature of these neurological cases as reported in the cerebral form of theileriosis (Giles et al1978;Bader et al 1986;Lawrence et al 2004).…”

“…The neuropathological changes include congestion and hemorrhages in the meninges and in the brain, and subacute-chronic areas of malacia. Microscopically, the obstruction of the arteries with a large numbers of parasitized lymphoblasts is the most prominent finding (Bader et al 1986;Lawrence et al 2004).…”

Cerebral theileriosis in a Holstein calf

“…The nervous signs occur as a result of vasculitis and lymphocytic inflammation of the brain (van Rensburg 1976, Khanna and others 1982, van Amstel 1982). Capillary engorgement, scattered punctuate haemorrhages on the surface of the brain, thrombosis of the meningeal vessels, haemorrhage in the cerebral ventricles and infarctions of the splenic vessels have been reported as postmortem features of the cerebral form (van Rensburg 1976, Khanna and others 1982, Bader and others 1986, Saville 2002).…”

Bovine Cerebral Theileriosis: First Molecular Confirmed Report in Cross Bred Cattle Calf in India

“…Otherwise, presence of only piroplasm stage in blood is indicative of benign form of theileriosis (Sivakumar et al, 2014). In the present case, occurrence of maximum number of annular form of piroplasmic stages along with presence of schizonts, which are di cult to demonstrate in chronic theileriosis and BCT, was indicative of T. annulata infection (Bader et al 1986), Species level differentiation of various Theileria species based on schizonts either by ultrastructure or by light microscope is quite impossible. Additionally, it is very tough for species level identi cation based upon piroplasm shape and size (Schein et al 1978).…”

“…More stress due to translocation may have altered the immune function and response to infection by the calf as calf along with mother was transported (Martin et al 2011). Possible trophism of the parasite towards the central nervous system leads to lesion in endothelium responsible for lymphoblastic accumulation and venous thrombi (Bader et al 1986). However, the severity of theileriosis depends on the inter play of parasite, vertebrate host, tick vector and environmental factors (Clift et al 2020).…”