Patterson-Kane J C, Carrick J B, Axon J E, Wilkie I, Begg A P
School of Veterinary Science, The University of Queensland, St. Lucia, Queensland 4072, Australia.
Equine Vet J. 2008 May;40(3):199-203. doi: 10.2746/042516408X292214.
The first outbreak of equine influenza virus (EIV) infection was confirmed in Australia in 2007. Some EIV-positive young foals died with bronchointerstitial pneumonia, an rare disease process in this age group that is often postulated to be caused by viral infection.
The aim of this study was to describe post mortem lesions in EIV-infected foals.
Post mortem examinations were conducted on 11 young foals (age 2-12 days) submitted to the Scone Veterinary Hospital, NSW over a 2-month period in 2007. The foals had presented with or developed fatal pneumonia, and were known or suspected to be EIV-positive. Equine influenza virus nucleic acid was detected in tissue specimens using an Influenza A group reactive real-time reverse transcriptase PCR assay.
Grossly there was diffuse or extensive pulmonary consolidation. Histological changes included: bronchiolar and alveolar necrosis; neutrophilic infiltration; hyaline membrane formation; and hyperplasia and squamous metaplasia of airway epithelium. Tissues for 10 foals were EIV-positive, with a positive nasal swab from the remaining animal.
This is the first detailed pathological description of bronchointerstitial pneumonia associated with EIV infection in young foals. It is also the first series of such cases in which a causative agent has consistently been detected.
Given the findings in this outbreak, and a previous outbreak in the UK in 1965 involving a similarly naive population, veterinary clinicians and pathologists should be aware that EIV can cause fatal bronchointerstitial pneumonia in young foals that do not have maternal immunity. The lesions did not differ from those previously reported in foals of various ages with bronchointerstitial pneumonia of other or undefined causes, indicating that this is most likely a stereotypical response to a variety of insults. Therefore, tissue specimens should be obtained from cases of pneumonia in young foals for virological and bacteriological testing.
2007年澳大利亚确诊了首例马流感病毒（EIV）感染疫情。一些EIV呈阳性的幼驹死于支气管间质性肺炎，这在该年龄组中是一种罕见的疾病过程，通常推测是由病毒感染引起的。
本研究的目的是描述EIV感染幼驹的尸检病变。
2007年，在两个月的时间里，对新南威尔士州斯科内兽医医院接收的11匹幼驹（年龄2 - 12天）进行了尸检。这些幼驹出现或发展为致命性肺炎，已知或怀疑EIV呈阳性。使用甲型流感病毒反应性实时逆转录聚合酶链反应检测组织样本中的马流感病毒核酸。
大体上有弥漫性或广泛性肺实变。组织学变化包括：细支气管和肺泡坏死；中性粒细胞浸润；透明膜形成；气道上皮增生和鳞状化生。10匹幼驹的组织样本EIV呈阳性，其余一匹动物的鼻拭子呈阳性。
这是首次对幼驹中与EIV感染相关的支气管间质性肺炎进行详细的病理学描述。这也是首次在一系列此类病例中持续检测到病原体。
鉴于此次疫情的发现，以及1965年英国发生的一次类似的疫情涉及同样缺乏母源免疫力的群体，兽医临床医生和病理学家应意识到，EIV可导致没有母源免疫力的幼驹发生致命性支气管间质性肺炎。这些病变与先前报道的由其他原因或不明原因引起的支气管间质性肺炎的不同年龄幼驹的病变并无差异，表明这很可能是对多种损伤的一种典型反应。因此，应从幼驹肺炎病例中获取组织样本进行病毒学和细菌学检测。
