A retrospective analysis was conducted to investigate the prevalence and seasonality of bovine viral diarrhoea virus (BVDV), bovine coronavirus (BoCV), bovine herpesvirus-1 (BoHV-1), bovine respiratory syncytical virus (BRSV) and parainfluenza virus-3 (PI3V) in calves (aged three months and below) in Ireland. Results from real-time PCR testing, including cycle threshold values, conducted on nasal swabs (single or pooled) submitted from 1364 respiratory disease outbreaks between January 1, 2008 and December 31, 2012 were included in this study. One or more viruses were detected in 34.6 per cent of submissions, with BoCV detected most frequently (22.9 per cent), followed by BRSV (11.6 per cent), PI3 V (7.0 per cent), BoHV-1 (6.1 per cent) and BVDV (5.0 per cent). The detection rate of all viruses was higher when pooled multiple swabs were submitted from outbreaks rather than single swabs, with these differences being significant for all except BVDV. Two or more viruses were detected in 39.4 per cent of positive submissions, with BoCV and BRSV most commonly present as one of the two partners in detection. With the exception of BVDV, which was detected all year round, the others showed a clear seasonal pattern, being most commonly detected in winter and spring.

BackgroundOvine pulmonary adenocarcinoma (OPA), caused by Jaagsiekte sheep retrovirus (JSRV), is characterised by the development of invariably fatal lung tumours primarily in adult sheep. High infection rates and disease prevalence can develop during initial infection of flocks, leading to on-farm economic losses and animal welfare issues in sheep with advanced disease. The disease has been reported in Ireland and is notifiable, but the presence of JSRV has never been confirmed using molecular methods in this country. Additionally, due to the difficulties in ante-mortem diagnosis (especially of latently-infected animals, or those in the very early stages of disease), accurate information regarding national prevalence and distribution is unavailable. This study aimed to confirm the presence of JSRV in Ireland and to obtain estimates regarding prevalence and distribution by means of an abattoir survey utilising gross examination, histopathology, JSRV-specific reverse transcriptase polymerase chain reaction (RT-PCR) and SU protein specific immunohistochemistry (IHC) to examine the lungs of adult sheep.ResultsLungs from 1911 adult sheep were examined macroscopically in the abattoir and 369 were removed for further testing due to the presence of gross lesions of any kind. All 369 were subject to histopathology and RT-PCR, and 46 to IHC. Thirty-one lungs (31/1911, 1.6%) were positive for JSRV by RT-PCR and/or IHC but only ten cases of OPA were confirmed (10/1911, 0.5%) Four lung tumours not associated with JSRV were also identified. JSRV-positive sheep tended to cluster within the same flocks, and JSRV-positive sheep were identified in the counties of Donegal, Kerry, Kilkenny, Offaly, Tipperary, Waterford and Wicklow.ConclusionsThe presence of JSRV has been confirmed in the Republic of Ireland for the first time using molecular methods (PCR) and IHC. In addition, an estimate of OPA prevalence in sheep at slaughter and information regarding distribution of JSRV infection has been obtained. The prevalence estimate appears similar to that of the United Kingdom (UK). Results also indicate that the virus has a diverse geographical distribution throughout Ireland. These data highlights the need for further research to establish national control and monitoring strategies.Electronic supplementary materialThe online version of this article (10.1186/s13620-017-0111-z) contains supplementary material, which is available to authorized users.

An approach to diagnosis of Jaagsiekte sheep retrovirus infection in sheep based on assessment of agreement between macroscopic examination, histopathologic examination and reverse-transcriptase polymerase chain reaction.