Department of Medicine and Epidemiology, University of California, Davis, California, USA.
Merck Animal Health, Wakefield, Virginia, USA.
Vet Rec. 2019 Mar 23;184(12):385. doi: 10.1136/vr.104919. Epub 2019 Mar 8.
Due to the inconsistent development of enteric signs associated with ECoV infection in adult horses, many practitioners collect nasal secretions rather than feces for the molecular diagnostic work-up of such horses.
ECoV infection should be considered in horses presenting with acute onset of fever, especially when nasal discharge is absent as one of the cardinal clinical sign.
A total of 277 adult horses with acute onset of fever were enrolled in this study. Feces were tested for ECoV and nasal secretions for common respiratory pathogens (equine herpesvirus (EHV)-1, EHV-4, equine influenza virus (EIV), equine rhinitis viruses (ERVs) and ) and ECoV by qPCR. Each submission was accompanied by a questionnaire requesting information pertaining to signalment, use, recent transportation, number of affected horses on the premise and presence of clinical signs at the time of sample collection.
The total number of horses testing qPCR-positive for ECoV in feces was 20 (7.2%), 4 of which also tested qPCR-positive for ECoV in nasal secretions. In the same population 9.0% of horses tested qPCR-positive for EHV-4, 6.1% for EIV, 4.3% for , 3.2% for ERVs and 0.7% for EHV-1. Draft horses, pleasure use, multiple horses affected on a premise and lack of nasal discharge were significantly associated with ECoV qPCR-positive horses.
The present study results showed that 7.2% of horses with acute onset of fever tested qPCR-positive for ECoV in feces, highlighting the importance of testing such horses for ECoV in feces. The various prevalence factors associated with ECoV qPCR-positive status likely relate to the high infectious nature of ECoV and breed-specific differences in management and husbandry practices.
ECoV infection should be suspected and tested for in horses presenting with acute onset of fever, lethargy and anorexia with no respiratory signs. A two-step approach should be consider in which respiratory secretions and feces should be collected from such horses and submitted to a diagnostic laboratory. If the respiratory secretions test negative by qPCR for a panel of respiratory pathogens, feces already submitted to the laboratory should be tested for ECoV.
由于与 ECoV 感染相关的肠内征象在成年马中不一致，许多临床医生会选择采集鼻分泌物而不是粪便进行此类马匹的分子诊断。
在出现急性发热的马匹中应考虑 ECoV 感染，尤其是当不存在发热的典型临床症状之一——鼻分泌物时。
共纳入 277 例急性发热的成年马。通过 qPCR 检测粪便中的 ECoV 和鼻分泌物中的常见呼吸道病原体（马疱疹病毒 1 型（EHV-1）、EHV-4、马流感病毒（EIV）、马鼻炎病毒（ERVs）和 ECoV）。每个送检样本均附有一份问卷，要求提供有关马匹一般信息、使用情况、近期运输、发病马数量和采样时的临床症状信息。
粪便中 ECoV 实时荧光定量 PCR 检测阳性的马匹总数为 20 匹（7.2%），其中 4 匹鼻分泌物也呈 ECoV 实时荧光定量 PCR 检测阳性。在同一群体中，9.0%的马匹 EHV-4 实时荧光定量 PCR 检测阳性，6.1%的马匹 EIV 实时荧光定量 PCR 检测阳性，4.3%的马匹 实时荧光定量 PCR 检测阳性，3.2%的马匹 ERVs 实时荧光定量 PCR 检测阳性，0.7%的马匹 EHV-1 实时荧光定量 PCR 检测阳性。役用马、娱乐用途、多匹马同时发病和无鼻分泌物与 ECoV 实时荧光定量 PCR 阳性马有显著相关性。
本研究结果显示，7.2%急性发热的马匹粪便中 ECoV 实时荧光定量 PCR 检测阳性，突出了对这类马匹进行粪便 ECoV 检测的重要性。与 ECoV 实时荧光定量 PCR 阳性状态相关的各种流行因素可能与 ECoV 的高传染性和品种特异性管理和养殖实践差异有关。
在无呼吸道症状的急性发热、嗜睡和厌食的马匹中应怀疑并检测到 ECoV 感染。应考虑采用两步法，从这些马匹中采集呼吸道分泌物和粪便，并将其送到诊断实验室。如果呼吸道分泌物实时荧光定量 PCR 检测针对一组呼吸道病原体为阴性，则应检测已送到实验室的粪便中是否存在 ECoV。
