Theileria infection with severe anemia and unhealed fracture in a sika deer Cervus nippon aplodontus (Cervidae: Cetartiodactyla).

An adult female sika deer (Cervus nippon aplodontus) inhabiting Nara Park, Nara, Japan, had broken bone injuries from a car accident. During its treatment, we found that the sika deer had severe anemia and the fracture remained unhealed throughout. Peripheral blood smear revealed piroplasms in the erythrocytes, which were identified as merozoites of undescribed Theileria species, widely found in sika deer in Japan. This is the report of a clinical case of Theileria infection, accompanied by severe anemia in a sika deer.

Increased Trypanosoma spp. richness and prevalence of haemoparasite co-infection following translocation.

BACKGROUND: Understanding how fauna translocation and antiparasitic drug treatment impact parasite community structure within a host is vital for optimising translocation outcomes. Trypanosoma spp. and piroplasms (Babesia and Theileria spp.) are known to infect Australian marsupials, including the woylie (Bettongia penicillata). However relatively little is known about these haemoparasites, or how they respond to management practices such as translocation. We monitored haemoparasites infecting woylies for up to 12 months during two fauna translocations to supplement existing woylie populations in three different sites (Dryandra, Walcott and Warrup East) within south-western Australia between 2014 and 2016, with the aim of investigating (i) how haemoparasite prevalence, Trypanosoma spp. richness and Trypanosoma spp. community composition varied over time and between different sites following translocation; and (ii) whether ivermectin treatment indirectly impacts haemoparasite prevalence. Using molecular methods, 1211 blood samples were screened for the presence of trypanosomes, and a subset of these samples (n = 264) were also tested for piroplasms. RESULTS: Trypanosomes and piroplasms were identified in 55% and 94% of blood samples, respectively. We identified five Trypanosoma species, two Theileria species, a single species of Babesia and a novel Bodo species. Trypanosoma spp. richness and the prevalence of haemoparasite co-infection increased after translocation. Prior to translocation, Trypanosoma spp. community composition differed significantly between translocated and resident woylies within Walcott and Warrup East, but not Dryandra. Six months later, there was a significant difference between translocated and resident woylies within Dryandra, but not Walcott or Warrup East. The response of haemoparasites to translocation was highly site-specific, with predominant changes to the haemoparasite community in translocated woylies occurring within the first few months following translocation. Ivermectin treatment had no significant effect on haemoparasite prevalence. CONCLUSIONS: This study contributes to our understanding of haemoparasite dynamics in woylies following translocation. The highly site-specific and rapid response of haemoparasites to translocation highlights the need to better understand what drives these effects. Given that haemoparasite prevalence and composition of translocated and resident animals changed significantly following translocation, we propose that parasite monitoring should form an essential component of translocation protocols, and such protocols should endeavour to monitor translocated hosts and cohabiting species.

Adding injury to infection: The relationship between injury status and genetic diversity of Theileria infecting plains zebra, Equus quagga.

Asymptomatic tick-borne infections are a common feature in wild herbivores. In human-dominated habitats, snare injuries to wild herbivores are common and are likely to co-occur with enzootic infections. The influence of injury on pattern, course and outcome of enzootic infection in wild herbivores is unknown. We identified Theileria species infecting zebra and assessed the relationship between host injury-status and parasitaemia, parasite diversity and selection regimes. We also determined host leucocyte differential as this can reveal mechanisms by which injuries influence infections. Theileria infecting zebra was identified using PCR and sequencing of the V4 region of the 18 s rRNA gene and confirmed with phylogenetic analyses. The influence of injury status on parasite infection patterns, genetic diversity and selection were assessed using population genetic tools. Parasitaemia estimated from prevalence and leucocyte differential were determined from microscopic examination of Giemsa stained thin blood smears. Phylogenetic and sequence analyses revealed that the zebra population studied was infected with three Theileria equi haplotypes. Parasitaemia was lower among injured compared to non-injured animals and lower during dry than wet season. Mean (±SD) genetic diversity was 0.386 (±0.128) in injured and 0.513 (±0.144) in non-injured zebra (P = .549). Neutrality tests indicated that T. equi is under strong purifying selection in injured females (Li & Fu's D* = -2.037) and demographic expansion in all zebra during the wet season (Tajima D = -1.904). Injured zebras had a higher median per cent of neutrophils (64% vs 37%) a lower median per cent of basophils (0% vs 1%) and eosinophils (2% vs 4.5%) than non-injured animals, suggesting a heightened immune response and a shift from a Th2 to Th1 T-Cell response favoring the elimination of intracellular parasites in injured animals. This study demonstrates the utility of population genetics in revealing factors influencing parasite diversity and infection patterns.

Prevalence studies for Theileria orientalis conducted during the early stages of the 2012 New Zealand epidemic of Theileria associated bovine anaemia.

Since 1982 there have been two epidemics of bovine anaemia associated with Theileria orientalis infection (TABA) in New Zealand. The latest and more serious epidemic started in 2012 and is associated with the T. orientalis (Ikeda) type. In 2013 the Ministry for Primary Industries (MPI) carried out several epidemiological investigations on the TABA epidemic, which included a series of on-farm herd prevalence studies. The aims of this paper are to present and summarise the results of these herd prevalence studies. The data were collected from March 2013 to September 2013 and comprised 26 farms. For 21/26 of these farms, a T. orientalis (Ikeda) positive index case of TABA precipitated the follow-up herd prevalence study. Each herd prevalence study involved a random sample of 10 cows for haematocrit, for piroplasm counts (number of Theileria infected RBCs per 1000 RBCs) and for PCR molecular diagnosis. Animals were diagnosed anaemic if the haematocrit ≤0.24. The results showed that for the index cases, the average haematocrit = 0.10 L/L and the average piroplasm count = 10.9 Theileria infected RBCs per 1000 RBCs, and for the herd prevalence studies the average haematocrit = 0.26 and the average piroplasm count = 6.9. The average herd prevalence of T. orientalis (Ikeda) PCR positive cattle and of anaemic cattle was 87% and 26% respectively. For dairy herds (n = 7 herds) it took, on average, 80 days for the within herd prevalence of anaemia to return to zero after the initial diagnosis. In conclusion the prevalence studies showed that infection rates and anaemia rates were already high in herds when the index case of TABA was observed. At the time, these prevalence studies significantly added to our understanding of the epidemiology of the evolving T. orientalis (Ikeda) epidemic and furthermore met the New Zealand MPI objective of being rapid and applied, fit for purpose and completed at a relatively low cost.

Monitoring Theileria orientalis (Ikeda)-associated bovine anaemia in affected cattle over time.

The aim of the study was to observe changes in haematocrit (HCT) over time in a New Zealand South Island dairy herd affected by an outbreak of Theileria-associated bovine anaemia (TABA; Ikeda). A secondary aim was to relate individual cow HCTs to the amount of Theileria orientalis Ikeda DNA present in the blood, as measured by cycle threshold values, using a quantitative PCR (qPCR). Over a 6 month period, blood samples from 19 randomly selected cattle were monitored from a herd of 600 dairy cows. The sampling interval was approximately fortnightly for the first six weeks, followed by sampling at between four and six week intervals. At the initial report of the outbreak, two from six cattle were anaemic (HCT<0.25L/L). Blood collected from 14 cattle 11 days later showed that 57% (95% CI 33-77%) of the cattle sampled were anaemic. Of the 19 cattle that went on to be monitored, 12 (63% 95% CI=41-81%) developed anaemia at some point during the period of monitoring. One of the anaemic animals did not meet the case definition for TABA Ikeda. For individual cattle, the average number of days between when cattle were first detected as anaemic and when HCT returned to normal was 53days (median=47 days, range=6-92 days). At the point of notification the amount of T. orientalis Ikeda DNA in the blood of the six cattle tested was low (Cq median=36), but 11days later the amount of DNA in blood of 14 additional cows tested was relatively high (Cq median=24). Levels of all 19 cows monitored continued to remain moderately high through the period of testing (Cq median=29). This was despite a general improvement in the HCT of affected cattle. In four of the 15 cattle positive to T. orientalis Ikeda where blood fractions (plasma and whole blood) were tested, it appeared that T. orientalis Ikeda (as measured by qPCR) dropped more rapidly in plasma fractions than in whole blood at the point that HCT started to return to normal levels. Despite the assumption that tick populations were low in the Canterbury region of the South Island the impact of TABA (proportion of herd affected and the average period that animals remained anaemic) on the case herd was still relatively high.

The diagnostic importance of coagulation parameters in cattle having natural theileriosis.

The purpose of this study was to determine the diagnostic importance of coagulation parameters in cattle with natural theileriosis. Nine Holstein cross-breed cattle with theileriosis as infected group and 6 healthy Holstein cattle as control group were used in the present study. Mean fibrinogen level, thrombin time (TT), activated partial thromboplastin time (aPTT) and prothrombin time (PT) were not statistically different when control and infected groups compared, except for the D-dimer concentration. Quantitative D-dimer concentrations were determined by immune-turbidimetric assay. D-dimer values increased significantly (p<0.05) in infected group (631.55 ± 74.41 µg/L) compared to control group (370.00 ± 59.94 µg/L). D-dimer sensitivity and specificity were also determined at cut-off concentrations (372 µg/L). Sensitivity and specificity of D-dimer values were determined to be 88.89% and 83.33%, respectively. D-dimer is thought to be important indicator in the evaluation of the prognosis in theileriosis cases. Analysis of D-dimer values before and after treatment in controlled case studies were suggested in future studies to enlighten the issue.

Pathogenic genotype of major piroplasm surface protein associated with anemia in Theileria orientalis infection in cattle.

Serious disease outbreaks in cattle caused by Theileria orientalis have emerged in the Asia-Pacific region. Genetic variables of the major piroplasm surface protein (MPSP) expressed on the surface of the piroplasm inside T. orientalis-infected erythrocytes are considered to be associated with variation in the pathogenicity of T. orientalis. Our study describes the clinically relevant MPSP types associated with anemia in Theileria-infected cattle. These results revealed that MPSP expression plays an important role in hematological alterations in Theileria-infected cattle, and that MPSP type 1 is strongly associated with bovine anemia, which can be a potential target for the prevention of bovine theileriosis.

Prevalence and effect of Theileria orientalis infection in homebred calves in the Gloucester region of New South Wales, Australia.

OBJECTIVES: To examine the prevalence of Theileria orientalis in the Gloucester area of New South Wales and its effect on individual animals. METHODS: Blood samples (EDTA and clotted blood) were collected from a total of 55 calves and their dams from 6 properties over a 16-week period. A total of 202 and 190 blood samples were collected from the calves and dams, respectively, and were examined via blood film for the presence of intraerythrocytic T. orientalis piroplasms. Packed cell volume (PCV) was measured to determine infection resulting in anaemia. The presence of antibodies against the T. orientalis major piroplasm surface protein (MPSP) was tested using ELISA. RESULTS: The overall prevalence of T. orientalis infection in both dams and calves from all herds examined was 95%. Mean peak parasitaemia was observed in calves between 6 and 9 weeks of age (P = 0.051), coinciding with a decline in mean PCV. Only 3 (6%) of the blood samples collected from the dams were positive for Theileria-associated antibodies and no significant relationship (P > 0.05) was found between the presence of antibodies in the dams and PCV levels in the calves. There was no evidence that passive transfer of antibodies from dams to calves protected the calves against a decline in PCV. CONCLUSION: This study confirmed a high prevalence of low-level Theileria infection, but low MPSP seroconversion rates, in dams and calves in an area where the disease has been endemic for a number of years.

[What makes a parasite "transforming"? Insights into cancer from the agents of an exotic pathology, Theileria spp]. / Comment et pourquoi un parasite peut-il être « transformant ¼ ? Apports d'agents de zoonoses exotiques, Theileria spp., à l'étude du cancer.

Theileria are obligate eukaryotic intracellular parasites of cattle. The diseases they cause, Tropical theileriosis and East Coast Fever, cause huge economic loss in East African, Mediterranean and central and South-East Asian countries. These apicomplexan parasites are the only intracellular eukaryotic parasites known to transform their host cell and represent a unique model to study host-parasite interactions and mechanisms of cancer onset.Here, we review how Theileria parasites induce transformation of their leukocyte host cell and discuss similarities with tumorigenesis. We describe how genomic innovation, epigenetic changes and hijacking of signal transductions enable a eukaryotic parasite to transform its host cell.

East Coast Fever Caused by Theileria parva Is Characterized by Macrophage Activation Associated with Vasculitis and Respiratory Failure.

Respiratory failure and death in East Coast Fever (ECF), a clinical syndrome of African cattle caused by the apicomplexan parasite Theileria parva, has historically been attributed to pulmonary infiltration by infected lymphocytes. However, immunohistochemical staining of tissue from T. parva infected cattle revealed large numbers of CD3- and CD20-negative intralesional mononuclear cells. Due to this finding, we hypothesized that macrophages play an important role in Theileria parva disease pathogenesis. Data presented here demonstrates that terminal ECF in both Holstein and Boran cattle is largely due to multisystemic histiocytic responses and resultant tissue damage. Furthermore, the combination of these histologic changes with the clinical findings, including lymphadenopathy, prolonged pyrexia, multi-lineage leukopenia, and thrombocytopenia is consistent with macrophage activation syndrome. All animals that succumbed to infection exhibited lymphohistiocytic vasculitis of small to medium caliber blood and lymphatic vessels. In pulmonary, lymphoid, splenic and hepatic tissues from Holstein cattle, the majority of intralesional macrophages were positive for CD163, and often expressed large amounts of IL-17. These data define a terminal ECF pathogenesis in which parasite-driven lymphoproliferation leads to secondary systemic macrophage activation syndrome, mononuclear vasculitis, pulmonary edema, respiratory failure and death. The accompanying macrophage phenotype defined by CD163 and IL-17 is presented in the context of this pathogenesis.

An observational study of the vertical transmission of Theileria orientalis (Ikeda) in a New Zealand pastoral dairy herd.

Although only recently recognised, Theileria orientalis (Ikeda) is now the most important infectious cause of anaemia in New Zealand cattle. The aim of this study was to test if vertical transmission of T. orientalis (Ikeda) from dam to calf across the placenta occurs in naturally infected New Zealand dairy cattle and to also test whether the infection status of the dam at calving affects the future susceptibility of its offspring to T. orientalis (Ikeda) infection. Dairy cows (n=97) and their calves were sampled at calving; and the calves again at 4 months of age. All samples were measured for haematocrit and screened for T. orientalis genotypes using a multiplex Buffeli, Chitose and Ikeda specific TaqMan assay. Ikeda positive samples were further tested by singleplex PCR in triplicate to calculate the Ikeda infection intensity as genomes/µl of blood from each infected animal. No T. orientalis (Ikeda) infected calves were born to either T. orientalis (Ikeda) infected or uninfected dams. There were 56/97 dams positive for T. orientalis (Ikeda) infection at calving and 79/90 calves positive for T. orientalis (Ikeda) infection at 4 months of age but no effect on calf susceptibility of dam infection status at calving. There was a significant negative effect of infection intensity on haematocrit after controlling for whether the infected animal was a dam or a 4 month old calf. Vertical trans-uterine transmission of T. orientalis (Ikeda) infection is unlikely in chronically infected dairy cows and thus not a factor in the epidemiology of T. orientalis (Ikeda) infection.

Application of quantitative PCR assays for diagnosing Ikeda and other Theileria orientalis types to examine associations between severity of anaemia and parasitaemia in bovine anaemia outbreaks.

AIMS: To use quantitative PCR assays to detect Theileria orientalis Ikeda type in cattle presumed infected with T. orientalis, to examine the relationship between theilerial piroplasm count and haematocrit (HCT), and the relationship with quantification cycle threshold (Cq) values. METHODS: Blood samples in EDTA (n=1,024), derived from herds affected by anaemia associated with T. orientalis infection (TABA) between April and October 2013, were submitted for testing using quantitative PCR (qPCR) assays for T. orientalis and Ikeda type. Nucleotide sequencing of the major piroplasm surface protein (MPSP) gene was performed on 16 samples to identify T. orientalis types. Blood smear and/or HCT results were supplied with most samples. For data analysis, the number of theilerial piroplasm per 1,000 erythrocytes counted was categorised as negative (0), low (1-9), moderate (10-100) or high (>100). HCT was categorised as severely anaemic (<0.15 L/L), mildly anaemic (0.15-0.24 L/L) or not anaemic (>0.24 L/L). Differences between categories in proportion of samples positive for Ikeda type or mean Cq value were examined using χ(2) tests or analysis of variance, respectively. RESULTS: Of 1,022 samples containing amplifiable DNA, 916 (90%) were positive for T. orientalis and 789 (77%) were positive for Ikeda type. Nucleotide sequencing of MPSP amplicons also identified the presence of Chitose and Buffeli types in 11 samples without Ikeda. Ikeda was detected in a greater proportion of severely anaemic (288/302; 95%) than mildly anaemic (227/252; 90%) cattle (p=0.02). In non-anaemic cattle, 344/406 (85%) were positive for T. orientalis and 247/406 (60%) were positive for Ikeda type. In samples from cattle that were piroplasm-positive, a greater proportion of anaemic (483/505, 96%) than non-anaemic (211/307; 69%) cattle were positive for Ikeda type (p<0.001). In piroplasm-negative cattle, 20/37 (54%) anaemic and 25/78 (32%) non-anaemic cattle were Ikeda-positive (p<0.05). The distributions of Cq values differed between piroplasm count and HCT categories (p<0.001). Mean Cq differed between high and negative, and low piroplasm categories (p<0.001), but not between high and moderate categories (p=0.81), and differed between severely anaemic and mildly anaemic (p<0.001), and non-anaemic categories (p<0.001). CONCLUSIONS: The Ikeda type was found in a high proportion of cattle during outbreaks of TABA in New Zealand. Analysis of Cq values suggested a relationship of Ikeda parasitaemia with severity of anaemia, but further investigation is required to better understand the role of parasitaemia in the pathogenesis of TABA.

Haemolytic anaemia associated with Theileria sp. in an orphaned platypus.

CASE REPORT: The clinical and laboratory findings in an orphaned juvenile female platypus (Ornithorhynchus anatinus) that presented with a severe anaemia and tick infestation are reported. The animal developed a terminal septicaemia and died. Antemortem clinical pathology, postmortem histopathology and 18S rDNA sequencing supported a diagnosis of extravascular haemolytic anaemia secondary to Theileria ornithorhynchi infection. CONCLUSION: Although T. ornithorhynchi infection is common in the platypus, this is the first case in which it has been shown to cause a haemolytic anaemia in this species and molecular characterisation of the organism has been described. A review of the previous literature concerning T. ornithorhynchi and possible treatment options for future cases are discussed.

Vertical transmission of Theileria lestoquardi in sheep.

This is the first report of an outbreak of Theileria lestoquardi abortion and stillbirth in a mob of 450 ewes in July 2012, during which, approximately 35 late-term ewes lost their fetuses over a 5-day period. A dead ewe and her aborted fetus were transported to the Ahvaz Veterinary Hospital for the diagnostic evaluation. The microbial cultures from the ewe vaginal discharges and fetal abomasal contents and the liver were negative. The blood films of the ewe and her fetus contained Theileria piroplasms and the impression smears from ewe liver and fetal spleen were positive for Theileria Koch blue bodies. The DNA was extracted from the liver and spleen of ewe and her fetus, respectively, and analyzed by polymerase chain reaction (PCR) using specific primers derived from the nucleotide sequences of 18S ribosomal DNA (rDNA) gene of T. lestoquardi. A single fragment of 428-bp fragment was amplified. The PCR product was directly sequenced and the alignment of the sequence with similar sequences in GenBank(®) showed 100% identities with 18S rDNA gene of T. lestoquardi. The present study is the first report of the T. lestoquardi vertical transmission that could be related to the abortion.

PCR detection of Babesia ovata from cattle reared in Japan and clinical significance of coinfection with Theileria orientalis.

We describe here the clinical significance of coinfection with Theileria orientalis and Babesia ovata in cattle. Anemia status in a herd of dairy cattle in Japan was investigated in relation to infection with these parasites. Our findings indicate that while B. ovata infection might not be the primary cause of anemia in the cattle, it may contribute to the clinical development of anemia in animals coinfected with both B. ovata and T. orientalis.

Clinical and haematological study on water buffaloes (Bubalus bubalis) and crossbred cattle naturally infected with Theileria annulata in Sharkia province, Egypt.

This study was conducted to investigate the clinical and haematological findings in water buffaloes and crossbred cattle naturally infected with Theileria annulata with special reference to the clinical picture of tropical theileriosis in Egyptian buffaloes. A total 50 field cases of buffaloes and cattle was clinically and laboratory investigated from March to June 2008. Forty-four buffaloes and cattle out of 50 were naturally infected with T. annulata and showed typical signs of infection. Six animals showed no clinical signs and were free from external, internal, and blood parasites. The clinical findings of examined cattle and buffaloes showed typical signs of tropical theileriosis: fever, enlargement of the superficial lymph nodes, severe lacrimation, bilateral conjunctivitis, photophobia, and corneal opacity. It was clear that the severity of clinical signs in infected buffaloes was more prominent than in infected cattle with persistence of some lesions after recovery as corneal opacity and pulmonary lesions. Haematological analysis revealed a significant decrease in RBCS count, PCV%, haemoglobin amount, and WBCs in the infected animals when compared to the control group. It was concluded from our study that T. annulata infection is associated with impairment and alteration of blood parameters in both cattle and water buffaloes. Theileriosis in water buffaloes might cause irreversible ocular changes that could lead to complete blindness. Data obtained in this study might be the basis for subsequent studies under natural and experimental field conditions.

An outbreak of haemolytic anaemia associated with infection of Theileria orientalis in naive cattle.

CASE HISTORY: An outbreak of haemolytic anaemia occurred when 87 cattle were introduced from a presumed non-infected herd from south Otago to a herd in Northland (n=580 cows), New Zealand, where theileriosis is endemic. CLINICAL FINDINGS: Clinical signs associated with Theileria spp. infection included lethargy, anorexia, inappetance, pale mucous membranes, and varying severity of anaemia. In the naive imported cattle, 11/29 (38%) of those tested showed haematological signs of anaemia (haematocrit (HCT) <0.25 L/L). A negative association was present between the HCT and the number of Theileria spp. organisms counted using light microscopy (correlation coefficient=-0.4; p<0.05). Haemoparasites consistent with Theileria spp. were observed on examination of a blood smear. Theileria orientalis group (Theileria buffeli/orientalis) species was confirmed using PCR and DNA sequencing, and other causes for anaemia were excluded in the most clinically severely affected cow. The 18S sequence data and phylogenetic analysis of the CoxIII sequences showed samples had the greatest similarity to T. orientalis Chitose from Japan. DIAGNOSIS: Haemolytic anaemia associated with infection of T. orientalis. CLINICAL RELEVANCE: Previous reports have suggested that T. orientalis group species may be non-pathogenic in healthy cattle, and an incidental finding in blood samples. However, this investigation provided evidence that in New Zealand, this pathogen is capable of causing clinical disease in cattle not necessarily debilitated by another disease. The potential for disease should be considered when naive cattle are brought in from non-endemic to endemic regions, for instance cattle from the South Island moved to regions where the vector for T. orientalis group species, Haemaphysalis longicornis, is active, and T. orientalis is present.

Evaluation of erythrocyte antioxidant mechanisms: antioxidant enzymes, lipid peroxidation, and serum trace elements associated with progressive anemia in ovine malignant theileriosis.

Ovine malignant theileriosis is a fatal disease that is characterized by severe progressive anemia. In order to elucidate the underlying mechanisms involved in anemia, this study was designed to assess the antioxidant status and erythrocyte oxidative injuries in Iranian fat-tailed sheep that suffered from malignant theileriosis. The infected animals (infected group), composed of 50 Iranian sheep about 1-2 years old, naturally infected with Theileria sp., were divided into three subgroups according to parasitemia rates (<1%, 1-3%, 3-5%), and ten non-infected animals were also selected as the control group. Blood samples were taken and hematological parameters, the activities of antioxidant enzymes including superoxide dismutase (SOD), glutathione peroxidase (GPX) and catalase, erythrocyte osmotic fragility, and serum concentrations of some trace elements (copper, iron, zinc, manganese, and selenium), were measured. As an index of lipid peroxidation, the level of malondialdehyde (MDA) was also determined. According to the results, a significant decrease in red blood cell (RBC) count, packed cell volume, the activities of SOD, GPX, and catalase (P <0.001), and also serum concentrations of Cu, Zn, Mn, and Se (P < 0.05) were evident in the infected sheep. In contrast, significantly increased levels of MDA and erythrocyte osmotic fragility (P < 0.001) as well as serum concentration of iron (P < 0.05) were recorded in the infected animals. The significant decrease in antioxidant enzyme activities and substantial elevated levels of lipid peroxidation and erythrocyte osmotic fragility associated with the increase in parasitemia indicate increased exposure of RBCs to oxidative damage. Also, it appears that disturbed antioxidant defense mechanisms can promote the development of anemia in ovine theileriosis.