Cardiac arrhythmias associated with piroplasmosis in the horse: A case report

Evaluation of Oxidative Status, Cytokines, Acute Phase Proteins and Cardiac Damage Markers in Sheep Naturally Infected with Babesia ovis

PURPOSE

Babesiosis is a tick-borne disease caused by protozoon species in the Babesia genus of the Babesiadae family. The systemic inflammatory response induced by infection is considered to be an important feature of the pathophysiology of ovine babesiosis. In this study, it was aimed to determine serum oxidative status, levels of some cytokines, acute phase proteins and heart damage markers in babesiosis infection.

MATERIALS AND METHODS

A sample of 40 sheep was used for this purpose, of which 20 were healthy and 20 were infected with Babesia ovis. Babesia infection was diagnosed from Giemsa-stained peripheral blood smears. Infection was also confirmed by the polymerase chain reaction (PCR). Sera from blood samples was tested for oxidative stress parameters (malondialdehyde [MDA], total antioxidant status [TAS], superoxide dismutase [SOD], catalase [CAT] and glutathione peroxidase [GPx]), cytokines (interleukins IL-6, IL-1β, IL-10, tumour necrosis factor α (TNF-α) and interferon-ϒ [IFN-ϒ]), acute-phase proteins (C-reactive protein [CRP], serum amyloid A [SAA] and haptoglobin [Hp]) and specific (troponin I [cTnI], creatine kinase-MB [CK-MB]) and nonspecific (lactate dehydrogenase [LDH], aspartate transaminase [AST]) cardiac damage markers.

RESULTS

MDA, SOD, CAT, Hp, TAS, IL-6, IL-10, TNF-α, IL-1β, INF-γ, AST, LDH, CK-MB mass and troponin I values were higher in the patient group than in the healthy group (P < 0.05). However, there was not found to be a statistical difference between the healthy and patient groups in terms of GPx, SAA and CRP values (P > 0.05).

CONCLUSIONS

It can be stated that serum levels of oxidative stress, some acute phase proteins and cardiac damage markers may increase in naturally infected sheep with babesiosis.

Insights into equine piroplasmosis in Venezuelan sport horses: Molecular diagnosis, clinical, and cardiovascular findings

Equine piroplasmosis (EP) is a tick-borne infectious disease highly prevalent in tropical and subtropical regions, such as Venezuela. EP affects wild and domestic equids leading to several clinical presentations, from asymptomatic to severely affected animals. In this study, thirty-three (33) sport horses under regular training activities and from endemic regions of north-central Venezuela were submitted to an observational survey, case-control, to describe the presence of clinical signs and natural EP infections. A conventional PCR assay targeting the SSU rRNA gene revealed EP etiologic agents in 13 out of 33 sampled horses (~ 39.4% infections). Nine (9) of these EP-positive samples were confirmed as infected with Babesia caballi (6/9 = 66.7%) or Theileria equi (3/9 = 33.3%) by DNA sequencing and BLASTN analyses. A phylogeny of SSU rRNA gene sequences revealed that these new B. caballi and T. equi sequences clustered within the worldwide distributed phylogenetic genotype A, respectively. No acute EP cases were observed in this study; however, six (6) PCR-positive animals displayed mild clinical signs compatible with EP, including a mild leukocytosis (P < 0.05). The heart rate variability frequency domain analysis in four (4) of these EP-positive infected animals revealed a significant (P < 0.05) higher low-frequency/high-frequency ratio suggesting a sympathovagal imbalance in these chronically infected animals. Other clinical and cardiovascular parameters were similar between the different groups. Sport horses are routinely submitted to intense training programs and sport-related activities that could lead to loss of the host-parasite equilibrium that characterizes enzootic regions, increasing the likelihood of infection reactivation and the risk of transmission. Heart rate variability analysis contributes to evaluate the sympathovagal balance and detecting homeostasis disturbances in sport horses. Molecular diagnostic tests for EP based on the detection of parasite DNA in equine blood samples should be included in the health programs of sport horses in endemic areas.

Evaluation of cardiovascular biomarkers and histopathological alterations in cattle naturally infected by Babesia bigemina

Hemolytic anemia and secondary hypoxia are characteristics of naturally occurring Babesia bigemina infection in cattle. The anemic phase comes with cardiovascular insufficiency due to hypoxia-induced system dysfunction; but to date there is no description of cardiac damage in the infected animals. Therefore, this study was undertaken to investigate hematological parameters, biomarkers of cardiac function and D-dimer in 13 cattle infected with B. bigemina which were unresponsive to standard treatment. The animals were necropsied and the cardiac tissue was examined for histopathologic alterations. A significant parasitemia burden-dependent increase in the cardiac biomarkers and D-dimer level were recorded in the infected cattle compared to the control animals. Thrombocytes count was also significantly lower in the infected animals than the control. Both macroscopic and microscopic hemorrhage, mononuclear infiltrates, and myocardial necrosis were the evident histopathologic findings. These findings suggest that B. bigemina infection can potentially induce cardiac dysfunction in cattle. Furthermore, mechanistic studies should be conducted to understand the mechanisms beyond cardiac complications.

First Case of Autochthonous Equine Theileriosis in Austria

A 23-year-old pregnant warmblood mare from Güssing, Eastern Austria, presented with apathy, anemia, fever, tachycardia and tachypnoea, and a severely elevated serum amyloid A concentration. The horse had a poor body condition and showed thoracic and pericardial effusions, and later dependent edema and icteric mucous membranes. Blood smear and molecular analyses revealed an infection with Theileria equi. Upon treatment with imidocarb diproprionate, the mare improved clinically, parasites were undetectable in blood smears, and 19 days after hospitalization the horse was discharged from hospital. However, 89 days after first hospitalization, the mare again presented to the hospital with an abortion, and the spleen of the aborted fetus was also PCR-positive for T. equi. On the pasture, where the horse had grazed, different developmental stages of Dermacentor reticulatus ticks were collected and subjected to PCR, and one engorged specimen was positive for T. equi. All three amplicon sequences were identical (T. equi genotype E). It is suspected that T. equi may repeatedly be transmitted in the area where the infected mare had grazed, and it could be shown that transmission to the fetus had occurred. Due to the chronic nature of equine theileriosis and the possible health implications of infection, it is advised to include this disease in the panel of differential diagnoses in horses with relevant clinical signs, including horses without travel disease, and to be aware of iatrogenic transmission from inapparent carrier animals.

The correlation between cardiac and skeletal muscle pathology in animal models of idiopathic inflammatory myopathies

Idiopathic inflammatory myopathies (IIMs) represent a heterogeneous group of disorders in which skeletal muscle is inappropriately targeted by the immune system. IIMs are characterized by inflammation of muscle and varying degrees of muscle dysfunction. Extra-muscular manifestations may involve heart, skin, joints, lungs, and gastrointestinal tract. Cardiovascular involvement is a feared event because is one of the leading causes of mortality in IIM patients. As the myocardium shares many features with the skeletal muscle, it is supposed that it can be affected by the same inflammatory processes, which take place during the different forms of IIMs. However, the full extent of this link and the mechanisms behind it are still not fully understood. Animal models have greatly improved our understanding of IIM pathomechanisms and have proven to be a useful tool for discovering therapeutic drug targets. Here we report the evidence of heart muscle involvement in different animal models of spontaneous IIMs, assuming a common autoimmune mechanism and presenting them as study models for human pathology.

Hematological and Biochemical Changes in Naturally Occurring Equine Piroplasmosis in Donkeys (Equus asinus) of Northwest of Iran

PURPOSE

Equine piroplasmosis is a tick-borne protozoal disease affecting horses, mules, donkeys and zebras and can lead to severe economic losses in the equine industry. There is limited information on clinical pathologic changes of equine piroplasmosis in donkeys. This study aims to investigate the impacts of babesiosis on various hematological and biochemical properties in naturally infected donkeys with Theileria equi and Babesia caballi.

METHODS

A total of 200 apparently healthy donkeys were randomly examined for the presence of equine piroplasmosis in blood samples. Of 200 samples, 11(5.5%) animals were positive for T. equi and 3(1.5%) of the samples were infected with B. caballi. 14 uninfected donkeys, were also selected as a control group.

RESULTS

The results of the comparison showed that infected donkeys presented a significant elevation (P < 0.05) of total leukocyte count, number of lymphocyte, monocyte, neutrophil and eosinophil, while showed a significant decreased in (P < 0.05) hemoglobin concentration (Hb), packed cell volume (PCV), red blood cells (RBCs), mean corpuscular volume (MCV) and mean corpuscular hemoglobin concentration (MCHC). The infected donkeys had significantly higher levels of total protein and total bilirubin (P < 0.05), whereas the amount of albumin was significantly lower in comparison to healthy animals (P < 0.05). It is interesting to note that the amounts of urea, cholesterol, creatinine, triglyceride, LDL and HDL, CK, AST, LDH, GGT, and Malondialdehyde were significantly higher (P < 0.05) in infected donkeys.

CONCLUSIONS

The current study describes laboratory findings in the affected donkeys which were good criteria for diagnosis and control of equine piroplasmosis in donkeys.

Twenty Years of Equine Piroplasmosis Research: Global Distribution, Molecular Diagnosis, and Phylogeny

Equine piroplasmosis (EP), caused by the hemoparasites Theileria equi, Theileria haneyi, and Babesia caballi, is an important tick-borne disease of equines that is prevalent in most parts of the world. Infection may affect animal welfare and has economic impacts related to limitations in horse transport between endemic and non-endemic regions, reduced performance of sport horses and treatment costs. Here, we analyzed the epidemiological, serological, and molecular diagnostic data published in the last 20 years, and all DNA sequences submitted to GenBank database, to describe the current global prevalence of these parasites. We demonstrate that EP is endemic in most parts of the world, and that it is spreading into more temperate climates. We emphasize the importance of using DNA sequencing and genotyping to monitor the spread of parasites, and point to the necessity of further studies to improve genotypic characterization of newly recognized parasite species and strains, and their linkage to virulence.

Pericardial Disease, Myocardial Disease, and Great Vessel Abnormalities in Horses

Pericardial, myocardial, and great vessel diseases are relatively rare in horses. The clinical signs are often nonspecific and vague, or related to the underlying cause. Physical examination usually reveals tachycardia, fever, venous distension or jugular pulsation, a weak or bounding arterial pulse, ventral edema, and abnormal cardiac auscultation such as arrhythmia, murmur, or muffled heart sounds. The prognosis depends on the underlying cause and the disease progression, and ranges from full recovery to poor prognosis for survival. This article focuses on the etiology, diagnosis, prognosis, and treatment of pericarditis, pericardial mass lesions, myocarditis, cardiomyopathy, and great vessel aneurysm or rupture.

First Report of Acute Bilateral Hyphema in a Theileria equi-Infected Kathiawari Horse

Theileria equi is a tickborne hemoparasite that can cause severe illness in equids. In this report, we are describing a condition of acute bilateral hyphema in a 4-month-old Kathiawari filly infected with T. equi. The horse showed clinical signs such as fever, lethargy, icterus, tachycardia, tachypnea, and bilateral hyphema. Laboratory diagnosis revealed anemia and thrombocytopenia. Atypical clinical manifestation of bilateral hyphema, to our knowledge, has never been reported so far in equids infected with T. equi. The diagnosis was confirmed by microscopic examination of Geimsa-stained blood smear. Specific and supportive therapy for T. equi allowed remission of clinical signs and laboratory profile abnormalities.

An experimental ovine Theileriosis: The effect of Theileria lestoquardi infection on cardiovascular system in sheep

The malignant ovine theileriosis is caused by Theileria lestoquardi, which is highly pathogenic in sheep. Theileriosis involves different organs in ruminants, but the effect of the disease on the cardiovascular system is unclear. To understand the pathogenesis of T. lestoquardi on the cardiovascular system, Baluchi breed sheep were infected with the mentioned parasite by releasing unfed adults of Hyalomma anatolicum anatolicum, which were infected with T. lestoquardi. The infected sheep were clinically examined on days 0, 2, 5, 7, 10, 12, 14, 17, and 21, and the blood samples were collected for biochemical parameters measurement. At termination of the experiment, the infected sheep were euthanized and pathological examinations of heart tissue were conducted. During experimental infection of sheep with T. lestoquardi, activities of cardiac troponin I (cTnI), lactate dehydrogenase, and aspartate aminotransferase, were significantly increased (P˂0.05), while a conspicuous decrease (P˂0.05) was observed in creatine phosphokinase activities. Alterations made in biochemical factors almost coincided with the presence of piroplasm in the blood and schizont in lymph nodes. Maximum and minimum of parasitemia in the sheep stood between 3.3% and 0.28%, respectively. In addition, electrocardiography revealed sinus tachycardia, sinus arrhythmia, sino-atrial block and ST-elevation, atrial premature beat, and alteration in QRS and in T waves' amplitude. Heart histopathological examination showed hyperemia, infiltration of mononuclear inflammatory cells into interstitial tissue, endocarditis, and focal necrosis of cardiac muscle cells. In addition, in one of the sheep, definite occurrence of infarction was observed. The results indicate that T. lestoquardi infection has devastating pathological impacts on the cardiovascular system of sheep. Furthermore, measurement of the cTnI amount is a useful biochemical factor for diagnosis and for better understanding of the severity and progression of the disease and its effects on cardiac tissue.

Troponin assays in the assessment of the equine myocardium

In 2000, troponin assays were adopted as the test of choice for detection of myocardial injury in man. This decision was made after extensive testing and followed a 60 year search for a biomarker of myocardial damage with sufficient analytical sensitivity and specificity. This has led to proliferation of assays for use in human medicine, each requiring extensive testing and validation before it could be made available on the open market for human use. The search for ever-more analytically sensitive assays and for a standard reference material continues. The adoption of troponin testing in veterinary medicine followed shortly after its development for use in man, providing a much-needed means of detecting and monitoring myocardial damage in horses. However, application of these tests in veterinary medicine has exclusively involved use of assays designed for and clinically validated in human patients. There is no mandated requirement for test validation in veterinary medicine and, while many of these assays have been shown to be capable of detecting equine troponin, the wide diversity of available tests, lack of validation, absence of protocols for their use and lack of standardisation make their application problematic. The objective of this review article is to address this issue, offering guidance where data are available and encouraging caution where there are none. Ultimately, the overall goal of this review is to examine critically the use of troponin assays in the horse and to promote the accurate and appropriate interpretation of valid results.

Review of equine piroplasmosis

Equine piroplasmosis is caused by one of 2 erythrocytic parasites Babesia caballi or Theileria equi. Although the genus of the latter remains controversial, the most recent designation, Theileria, is utilized in this review. Shared pathogenesis includes tick-borne transmission and erythrolysis leading to anemia as the primary clinical outcome. Although both parasites are able to persist indefinitely in their equid hosts, thus far, only B. caballi transmits across tick generations. Pathogenesis further diverges after transmission to equids in that B. caballi immediately infects erythrocytes, whereas T.equi infects peripheral blood mononuclear cells. The recent re-emergence of T.equi in the United States has increased awareness of these tick-borne pathogens, especially in terms of diagnosis and control. This review focuses in part on factors leading to the re-emergence of infection and disease of these globally important pathogens.

Cardiac troponin is the most effective translational safety biomarker for myocardial injury in cardiotoxicity

There is an overwhelming weight of evidence that certifies cardiac troponin (cTn) as the preferred, defacto, translational, safety biomarker for myocardial injury in cardiotoxicity. As well as being the gold standard for cardiac injury in man, it has been widely used for clinical assessment and monitoring of cardiac toxicity in humans being treated for cancer. Furthermore, several dozen preclinical published studies have directly confirmed its effectiveness in laboratory animals for assessment of cardiotoxicity. It is gradually being reverse translated from human into animal use as a safety biomarker. Its use is especially merited whenever there is any safety signal indicating potential cardiotoxicity and its required inclusion as a routine biomarker in preclinical safety studies seems on the horizon. There are some considerations that are unique to use of cTn assays in animals. Lack of awareness of these has, historically, significantly inhibited the introduction of cTn as a safety biomarker in preclinical toxicology. Firstly, cross-species reactivity is usually but not always high. Secondly, there is a background of cardiac injury that needs to be controlled for, including spontaneous cardiomyopathy in Sprague Dawley rats, and inappropriate blood collection methods. Also, there are faster kinetics of clearance in rats than for humans. Also, coincident muscle injury is frequent with cardiotoxicity and requires a skeletal muscle biomarker. Because cTn assays were developed for detection of gross cardiac necrosis, such as occurs with myocardial infarct, the more sensitive assays should be used for preclinical studies. However, analytic sensitivity is higher for standard preclinical studies than for clinical diagnostic testing because of use of concurrent controls and use of batch analysis that eliminates interassay variability. No other biomarker of myocardial injury comes close to cTn in effectiveness, including CK-MB, LDH-1 and 2, myoglobin, and FABP3. In addition to the use of cTn for monitoring active myocardial degeneration, there is growing evidence that measurements of brain natriuretic peptide (BNP) may be effective for monitoring drug-induced left ventricular dysfunction.