Introduction

Foot-and-mouth disease (FMD) causes mortality in calves due to myocarditis; however, the effects of FMD virus on cardiac arrhythmogenesis and Purkinje cells are unknown. Identifying diagnostic and prognostic markers in FMD-affected calves may be useful in disease management in the endemic countries.

Materials and methods

A total of 81 FMD-affected calves were prospectively monitored till death or recovery. Foot-and-mouth disease was diagnosed by serology and reverse transcriptase–polymerase chain reaction (RT-PCR). Electrocardiography was recorded and serum cardiac biomarkers were measured. Histopathological examination of the ventricular myocardium was carried out in the calves that died of FMD (n = 33). Apparently healthy calves (n = 15) served as control.

Results

Serology and RT-PCR consistently revealed that the FMD was caused by serotype O virus. Arrhythmias occurred in 62 of 81 (76.5%) FMD-affected calves, of which, ventricular premature complexes (VPCs) were the most common type (22%). The combined mortality rate due to ventricular tachycardia, polymorphic VPCs, and atrial fibrillation was 27.6%. Receiver operating characteristic curve analysis revealed that cardiac troponin I (cTnI) concentrations of ≥1.3 ng/mL were diagnostic of myocarditis with a sensitivity and specificity of 90% and 100%, respectively. Similarly, serum cTnI concentrations of <6.4 ng/mL were a good predictor of survival [odds ratio of 263; 95% confidence interval: 29–2371]. Histopathology of the myocardium revealed hyaline degeneration, necrosis, edema, mononuclear cell infiltration, and disruption by fibroblasts. Atrophy of the Purkinje cells was also present.

Conclusions

FMD induces cardiac arrhythmias and Purkinje cell pathology in the calf. Portable ECG coupled with assay of serum cTnI would help in predicting survival in FMD-affected calves.

中文翻译：

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心律失常的表征、心脏生物标志物的评估及其与患有口蹄疫的小牛的存活率的关系

介绍

口蹄疫 (FMD) 导致小牛因心肌炎而死亡；然而，FMD 病毒对心律失常和浦肯野细胞的影响尚不清楚。鉴定受 FMD 影响的小牛的诊断和预后标志物可能有助于流行国家的疾病管理。

材料和方法

总共对 81 头受 FMD 影响的小牛进行了前瞻性监测，直至死亡或康复。口蹄疫通过血清学和逆转录酶-聚合酶链反应（RT-PCR）诊断。记录心电图并测量血清心脏生物标志物。在死于 FMD 的小牛 (n = 33) 中进行了心室心肌的组织病理学检查。显然健康的小牛 (n = 15) 作为对照。

结果

血清学和 RT-PCR 一致表明 FMD 是由血清型 O 病毒引起的。81 只受 FMD 影响的小牛中有 62 只出现心律失常 (76.5%)，其中室性早搏 (VPC) 是最常见的类型 (22%)。由室性心动过速、多形性 VPC 和心房颤动引起的综合死亡率为 27.6%。受试者工作特征曲线分析显示，心肌肌钙蛋白 I (cTnI) 浓度≥1.3 ng/mL 可诊断心肌炎，其敏感性和特异性分别为 90% 和 100%。同样，<6.4 ng/mL 的血清 cTnI 浓度是存活率的良好预测指标 [比值比为 263；95% 置信区间：29–2371]。心肌的组织病理学显示透明变性、坏死、水肿、单核细胞浸润和成纤维细胞破坏。

结论

FMD 在小腿中诱发心律失常和浦肯野细胞病理学。便携式心电图结合血清 cTnI 检测将有助于预测受 FMD 影响的小牛的存活率。