Studies on alterations of clinical and hemato-biochemical parameters before and after treatment in calves naturally infected with theileriosis

Clinical Findings, Laboratory Results, Electrocardiography and Echocardiography Findings in Dairy Buffaloes with Theileriosis

PURPOSE

Tropical theileriosis is a tick-borne haemoprotozoan disease, and cardiac function assessment in buffaloes with theileriosis was poorly documented.

METHODS

The Present study was carried out from April 2022 to December 2022. Theileriosis was confirmed by microscopic examination of stained blood smears and lymphnode smears further confirmed by PCR assay. Electrocardiography was performed by using the base apex lead system, and echocardiography was performed by using the right parasternal view.

RESULTS

The incidence of theileriosis was 16.25% by examination of stained blood smears, and 30.42% by PCR examination in 240 buffaloes. Repeatedly noted clinical signs were the absence of rumination, anorexia, loss of milk yield, depressed demeanour, emaciation, hyperthermia, lymphadenopathy, tick infestation, tachycardia, cardiac arrhythmia, and increased intensity of heartbeat. Haematological findings disclosed decreased haemoglobin, packed cell volume, total erythrocyte count, and neutrophils; increased eosinophils and monocytes. Serum biochemical findings revealed decreased albumin, albumin/globulin ratio, glucose, calcium, phosphorous, sodium, potassium, and chloride; increased globulin, aspartate aminotransferase, bilirubin, blood urea nitrogen, creatinine, cholesterol, lactate dehydrogenase, gamma-glutamyl transferase, and creatine kinase myocardial band isoenzymes. Electrocardiography explorations were sinus tachycardia, broad T wave, and sinus arrhythmia. Echocardiography examination showed ventricular wall thickening, cardiac chamber dilatation, valvular defects/valvular regurgitation, and pericarditis/cardiac tamponade.

CONCLUSION

The present research proposes the changes in the electrocardiography and echocardiography findings in buffaloes with theileriosis, which are essential in clinics to identify the secondary complications during theileriosis and formulate therapeutics.

Polyclonal antibody-based immunohistochemical detection of intraleukocytic Theileria parasites in roan and sable antelopes

Theileria parasites commonly infect African wild artiodactyls. In rare roan (Hippotragus equinus) and sable (H. niger) antelopes, Theileria sp. (sable)-associated calf mortalities constrain breeding programs. The pathogenicity of most leukocyte-transforming Theileria spp. originates in their invasion of and multiplication in various mononuclear leukocytes, the transformation of both infected and uninfected leukocytes, and their infiltration of multiple organs. Understanding the pathogenesis of theileriosis can be improved by the use of immunohistochemistry (IHC) to identify the localization of the parasites in tissue sections. Our aim was to develop a reproducible IHC assay to detect leukocyte-associated Theileria parasites in formalin-fixed, paraffin-embedded roan and sable tissues. Polyclonal antibodies were purified from the sera of 5 roans from an area endemic for Theileria sp. (sable) and tested for IHC reactivity in 55 infected and 39 control roan and sable antelopes, and for antigen and species cross-reactivity in an additional 58 cases. The 3 strongest antibodies consistently detected intraleukocytic theilerial antigens in known positive cases in roan and sable antelopes, and also detected other Theileria spp. in non-hippotraginid wild artiodactyl tissues. The antibodies did not cross-react with other apicomplexan protozoa, with the exception of Cryptosporidium. Given that PCR on its own cannot determine the significance of theilerial infection in wild ruminants, IHC is a useful laboratory test with which to confirm the diagnosis in these species.

Clinical and hematologic features of experimental theileriosis in roan calves (Hippotragus equinus)

Theileria sp. (sable) infection commonly causes significant calf mortality in endangered roan antelopes (Hippotragus equinus). Schizont-induced leukocyte transformation and systemic immune dysregulation with associated cytopenias characterizes theileriosis in livestock. Data on related hematologic alterations are scarce in roan antelopes. The objective of this study was to investigate temporal changes in selected clinical parameters and hematologic measurands in experimentally infected (EI) roan calves. Six of eight calves developed theileriosis after inoculation with a Theileria sp. (sable)-infected tick stabilate. Consecutive measures of rectal temperature, lymph node size, white blood cell count (WBC), packed cell volume (PCV), hemoglobin concentration, differential leukocyte counts, leukocyte and erythrocyte morphology and percentage parasitemia were recorded. Data were compared with 15 age-matched PCR-negative control calves and nine older immune animals that had recovered from natural infection. Two non-pyrexic EI calves recovered uneventfully. Six pyrexic calves were treated, four of which died. Time to pyrexia and/or observation of schizonts and piroplasms was approximately two weeks. Total WBCs were unchanged post-infection (PI); neutrophils and typical monocytes decreased whereas typical lymphocytes (Ls) and atypical mononuclear leukocytes (AMLs), which were grouped together, increased. Parasitized and non-parasitized lymphocyte and AML (L/AML) size increased significantly PI. Piroplasms occurred intermittently at low frequencies («1 % of erythrocytes) after infection. Fatally infected calves were dehydrated, anemic, and icteric with hemorrhages and multi-organ infiltration by AMLs. The PCV and hemoglobin concentration increased PI, and platelet clumps were consistently observed. Experimental acute theileriosis in roan antelopes follows a similar pattern of disease progression to that in domestic livestock. Parasitized and non-parasitized AMLs are pivotal to the pathogenesis and require phenotypic characterization if we are to further our understanding of disease progression and severity in roan antelopes.