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  • Publication
    Prevalence and distribution of exposure to Schmallenberg virus in Irish cattle during November 2012 to November 2013
    Background: Schmallenberg virus (SBV) was first identified in November 2011. It is a novel Orthobunyavirus (family Bunyaviridae) whose main ill effect is congenital malformation of the musculoskeletal and central nervous systems. It is borne by Culicoides spp., and has spread extensively in western Europe. The first case of SBV in Ireland was diagnosed in October 2012. It was anticipated that once the virus emerged in Ireland that there would be wide scale or nationwide spread over the course of the 2013 vector season. The objectives of this study were to determine the seroprevalence and distribution of exposure to Schmallenberg virus in Irish cattle from November 2012 to November 2013. Methods: Samples of brain for the pathology based surveillance were collected from malformed bovine and ovine foetuses submitted for post mortem examination. These samples were tested for SBV using RT-qPCR. Three serological surveys were carried out on sera submitted for the national brucellosis eradicartion programme. A spatial analysis of both sets of data was carried out. Results: Between October 2012 and 10th May 2013, SBV was confirmed by RT-qPCR in brain tissues from malformed foetuses obtained from 49 cattle herds and 30 sheep flocks in Ireland. In national serosurveys conducted between November 2012 until November 2013 the herd-level and animal-level SBV seroprevalences in cattle were 53 and 36 % respectively for the first survey, 51 and 35 % for the second survey and 53 and 33 % for the third survey. The herd level seroprevalence in counties ranged from 0 to 100 %, with the counties in the south and southeast having the highest seroprevalence (>50 %), the midlands a moderate herd level seroprevalence (10–50 %) while northern and north western counties had a low herd level seroprevalence (0–10 %). There was close spatial agreement between the results of the two different targeted surveillance strategies. Conclusions: At the end of the 2012 vector season, there was widespread exposure to SBV among herds in southern and south eastern Ireland. During 2013, there was little or no evidence of further outward spread, unlike the situation in several other European countries. Given the lack of evidence for circulation of the virus since 2012, it is likely that the younger age cohort in herds previously exposed to SBV and substantial proportions of animals of all ages on the margins of affected areas are immunologically naïve to SBV, and would be susceptible to infection if the virus were to re-emerge.
    Scopus© Citations 13  216
  • Publication
    Exposure to Schmallenberg virus in Irish sheep in 2013
    Fetal malformation due to Schmallenberg virus (SBV) was diagnosed in 49 cattle herds and 30 sheep flocks in the south and south east of Ireland in 2013. Serological and pathological studies in cattle, and pathological studies in sheep indicated SBV exposure was confined to the south and south east of Ireland. It was anticipated that SBV exposure would spread north westwards over the course of the 2013 vector season. The objectives of this study were to determine the geographic distribution of SBV exposure in Irish sheep before and during the 2013 vector season, and to determine if SBV was active in flocks where SBV infection had been previously confirmed. There was no further increase in the geographic extent of exposure to SBV during the course of 2013, nor was there evidence of SBV transmission during 2013 in flocks where SBV had been previously confirmed.
      286Scopus© Citations 5