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.

MALFORMED fetuses attributable to Schmallenberg virus (SBV) were found in 49 cattle herds and 30 sheep flocks exclusively in the southern and eastern parts of Ireland (Barrett, D., More, S. J., O'Neill, R., Bradshaw, B., Casey, M., Keane, M., McGrath, G. & Sammin, D. (Submitted) Prevalence and distribution of exposure to Schmallenberg virus in Irish cattle during November 2012 to November 2013). National bovine serological studies late in 2012 and 2013 confirmed exposure to SBV was effectively confined to the south-east (Barrett and others, submitted). It was unclear whether the distribution of seroconversion in cattle reflected the situation in sheep. Several studies have shown that Culicoides species preferentially feed on cattle rather than sheep (Ninio and others 2011, Ayllon and others 2014, Elbers & Meiswinkel 2014), leading to lower levels of seroconversion in sheep flocks than in neighbouring cattle herds (Gache and others 2013). It was anticipated that SBV would continue to spread across the country over the second (2013) vector season, similar to the experience in mainland Europe (Garigliany and others 2012, Veldhuis and others 2013, Balmer and others 2014). The objectives of this study were to determine the geographical distribution of SBV exposure in Irish sheep before and during the 2013 vector season, and to determine if SBV was active in 2013 in flocks where SBV infection was previously confirmed. Two studies were conducted, each in different sets of sheep flocks. In the first study, serological samples were collected in 32 sentinel flocks sampled on two or three occasions at six-week intervals between May 2013 and September 2013. The flocks were distributed across the country (15, 8 and 9 flocks from the south-east, midlands and north-west, respectively), and had been volunteered through Sheep Ireland (www.sheep.ie) (n=24) and veterinary practitioners (n=8). For welfare and legislative reasons, individual adult sheep were blood sampled only once. In the second study, serological samples were collected in 14 sheep flocks where SBV infection had been confirmed in malformed fetal lambs the previous spring. In these flocks, samples were collected from 15 lambs aged between 8 months and 10 months on a single occasion, in November 2013. For both studies, it was estimated that a minimum number of 13 samples would be required per round of sampling, to ascertain freedom from infection assuming a flock prevalence of 40%, a test sensitivity of 80% and a test specificity of 99%. In practice, 15 animals were sought at each round of sampling. For both studies, sera were tested using commercially available test kits, an indirect ELISA (Idexx Laboratories) and a competition ELISA (ID.vet), each according to the manufacturer's instructions. In the second study, sera were additionally tested by serum neutralisation test (SNT), with a threshold titre of 1:16 used to determine SBV seroconversion (Loeffen and others 2012, Bouwstra and others 2013). In the first study, there were 17 (53%) seropositive flocks, including all 15 in the east and south-east (Fig 1), with no subsequent change in SBV status. A single seropositive animal was found in two flocks: in counties Sligo and Meath, in the north-west and north-east, respectively. These two seropositive animals had been purchased from flocks in the south-east region in 2012 and it was assumed these animals had seroconverted before movement. In the second study, two (14.3%) flocks had multiple seropositive lambs. Each flock had used vaccination and the lambs were seropositive by both ELISA methods but not by SNT. Two other flocks each had a single seropositive lamb; in both cases, the lamb was seropositive to SNT and one or both ELISA methods (Table 1). Location of the 32 study flocks in the first study, by Schmallenberg virus (SBV) serological status. County-level evidence of SBV exposure (% holdings positive) was based on serological surveys conducted in cattle during 2012–13 (Barrett, and others, submitted). Counties included in the second study (of 2013-born lambs) are highlighted (Carlow [CW], Cork [CK], Kilkenny [KK] and Wexford [WX]) In Irish sheep flocks, seroconversion to SBV virus was confined to the south and south-east of the country with no further circulation in 2013, similar to earlier results from Irish cattle (Barrett and others, submitted). In considering the probability of transmission of SBV from the south and east coast to locations further inland, it is noteworthy that the prevailing wind direction in Ireland is from the south-west and as such this would not have facilitated long-distance windborne spread of biting midges in a north-westerly direction. Further spread would be largely reliant on local transmission dynamics. Regional differences in availability of suitable vectors is also unlikely to explain the limited geographical spread of SBV as a previous study demonstrated several potentially bluetongue-competent Culicoides species were abundant and widely available throughout Ireland, especially in the northern half of the country (McCarthy and others 2010). However the timing of the initial incursion of SBV, which is considered to have occurred during the latter half of the vector active season (O'Neill and others 2014), may provide an explanation. Scottish modelling has shown that SBV introduction late in the vector season under climatic conditions similar to Ireland markedly reduced the spread of infection compared with an introduction earlier in the vector season (Bessell and others 2013). That study also showed that mean Scottish summer temperatures facilitate only limited spread, as vector life cycles are very temperature dependent. Temperatures in the south-east of Ireland in the summer and autumn of 2012 were approximately 1°C less than the 30-year average (Anon 2015). Therefore the incursion of SBV relatively late in the vector season in a year with below average temperatures was likely to have curtailed the spread of Irish SBV in 2012. In flocks with confirmed SBV infection in the first (2012) vector season, there was no evidence of detectable exposure among 2013-born lambs. This study was carried when maternal antibodies were presumed to have waned (Elbers and others 2014). While there was evidence of seroconversion in two lambs in separate non-vaccinated flocks, occasional antibody detections among lambs more than six months of age have been attributed to persistent maternal antibodies (L. van Wuyckhuise, personal communication) or false positives (Veldhuis and others 2015). There is a possibility this seroconversion occurred as a result of exposure to SBV in utero. It is interesting to note the variable antibody response among sheep vaccinated for SBV. The spatial distribution of seroconversion in sheep closely mirrored both the spatial distribution of confirmed cases of clinical SBV in sheep and the distribution of exposure SBV among cattle. This suggests that future serological studies in cattle for SBV, and other vector borne viral pathogens of ruminants, might reasonably be used to predict the exposure in sheep, as bovine samples are more readily available and midges have a known preference for cattle over sheep (Ayllon and others 2014, Elbers and Meiswinkel 2014). The incomplete seroconversion in flocks exposed to SBV during 2012 and the lack of SBV seroconversion among 2013-born lambs in those flocks would suggest that a sizeable proportion of the current sheep population in south-east Ireland is immunologically naive to SBV should re-emergence or reintroduction occur.

The voluntary phase of an industry-led national Bovine Viral Diarrhoea (BVD) eradication programme began in Ireland on January 1, 2012 with the goal of progressing to a compulsory programme in 2013. The development and implementation of the programme in 2012 was informed by a review of current and prior eradication programmes elsewhere in Europe and extensive stakeholder consultation. The programme was based on tissue tag testing of newborn calves in participating herds, with the status of the mothers of calves with positive or inconclusive results requiring clarification. Participating herd owners were required to comply with a series of guidelines, including not selling cattle suspected of being persistently infected. For herds compliant with the guidelines, the results from 2012 counted as one of three years of tag testing anticipated in the compulsory phase of the programme. Testing was carried out in laboratories designated for this purpose by the cross-industry BVD Implementation Group that oversees the programme. Results were reported to a central database managed by the Irish Cattle Breeding Federation, and the majority of results were reported to farmers' mobile telephones by SMS message. A detailed review of the programme was conducted, encompassing the period between January 1, 2012 and July 15, 2012, based on results from approximately 500,000 calves. This paper describes the establishment and structure of the programme, and the outcomes of the review, including findings at herd and animal level.

Six ovine fetal brains were harvested 33 to 35 days postchallenge from 5 ewes, each of which was given 3000 Toxoplasma gondii oocysts on day 90 of pregnancy. Histopathologic examination of transverse sections taken at 13 levels in the fetal brains revealed the presence of toxoplasmosis-related lesions in all 6 brains. However, lesions were not randomly distributed (P = .007); they were most numerous at the level of the optic tract, the rostral margin of the pons, and 4 mm caudal to the ansate sulcus and were absent in all sections at the level of the caudal cerebellum. Lesion distribution may be due to hemodynamic factors, differences in the expression of endothelial surface receptor molecules at the level of the blood-brain barrier, or the presence of localized permissive/inhibitory factors within the brain. The results have implications for the selection of areas of brain from aborted ovine fetuses to be examined histopathologically for laboratory diagnosis.

Toxoplasma gondii, an intracellular protozoan parasite, is one of the major causes of infectious abortion in sheep. To further understand the pathogenesis of toxoplasmosis, serum, amniotic and allantoic fluids and foetal stomach contents were collected from experimentally infected pregnant ewes to determine pathogen numbers and other markers of infection. Fifteen pregnant ewes (90 days of gestation) were each orally inoculated with 3000 sporulated oocysts of T. gondii. Serum samples were collected weekly following challenge. Amniotic and allantoic fluids and foetal stomach contents were collected at 21, 25, 28, 33 and 35 days post-infection. Characteristic placental lesions were detected in 1 of 4 challenged ewes at day 25, 3 of 4 challenged ewes at day 28 and in all challenged ewes at days 33 and 35 post-infection. T. gondii was detected only sporadically in amniotic and allantoic fluids before 35 days of infection, by real-time PCR, and only in ewes with placental lesions. At 35 days post-infection, high numbers of parasite were detected in both amniotic and allantoic fluids. An increase in the number of fluids from challenged animals with IgM and IgG was detected over time, except for IgG in allantoic fluid, which was detected in all samples from day 21 post-infection. IgG in amniotic and allantoic fluids was shown to be specific for T. gondii, and reacted with antigens with an apparent molecular mass of approximately 22 kDa and 30 kDa. Results suggest a maternal source of immunoglobulin in the allantoic fluid and a foetal source of immunoglobulin in the amniotic fluid early in infection but that both sources may contribute immunoglobulin to both fluids at a later stage.

A real-time PCR (rt-PCR) targeting the 529-bp repeat element (RE) of Toxoplasma gondii was used to detect and quantify the parasite burden in maternal and foetal tissues in 18 seronegative ewes infected with 3000 toxoplasma oocysts on day 90 of pregnancy. The infected ewes were sacrificed in groups of 4-6 at 21, 25, 33 and 35 days post-challenge. Ten sham inoculated pregnant ewes were used as controls. T. gondii was not detected in the control ewes or their foeti. The parasite was only detected in the maternal tissues in a few of the challenged ewes on a small number of occasions where it was identified in spleen and uterine lymph nodes. T. gondii was detected in the foetal spleen and liver at the early sacrifice times but only sporadically thereafter. In the case of amniotic, allantoic and foetal aqueous humor samples T. gondii was only detected on a small number of occasions. However, it was found in the majority of the foetal lung and placentome samples throughout the study period, while placentomes and foetal brains contained high levels of the parasite during the later stages. Histopathological examination of placentome and brain tissue from the foeti in the present study revealed a strong correlation between histopathological lesions and quantities of the parasite DNA detected. These results indicate that the cotyledonary component of the foetal membranes is the sample of choice for the diagnosis of T. gondii by rt-PCR, followed by foetal lung and brain.

ABSTRACTChlamydophila abortusis an intracellular pathogen and the etiological agent of enzootic abortion of ewes (EAE).C. abortushas a biphasic development cycle; extracellular infectious elementary bodies (EB) attach and penetrate host cells, where they give rise to intracellular, metabolically active reticulate bodies (RB). RB divide by binary fission and subsequently mature to EB, which, on rupture of infected cells, are released to infect new host cells. Pregnant ewes were challenged with 2 × 106inclusion forming units (IFU) ofC. abortuscultured in yolk sac (comprising both EB and RB). Serum samples were collected at 0, 7, 14, 21, 27, 30, 35, 40, and 43 days postinfection (dpi) and used to identify antigens ofC. abortusexpressed during disease. Additionally, sera from fetal lambs were collected at 30, 35, 40, and 43 dpi. All serum samples collected from experimentally infected pregnant ewes reacted specifically with several antigens of EB as determined by one-dimensional (1-D) and 2-D gel electrophoresis; reactive antigens identified by mass spectrometry included the major outer membrane protein (MOMP), polymorphic outer membrane protein (POMP), and macrophage infectivity potentiator (MIP) lipoprotein.

An appreciation of the complexities of placental structure and function is essential to understanding the pathogenesis of infectious placentitis and abortion. This review aims to illustrate aspects of ovine pregnancy and placentation that will assist both the research worker and the diagnostic pathologist. Morphologically, the ovine placenta is classified as being chorioallantoic, villous, cotyledonary and synepitheliochorial. Apposition of foetal and maternal tissues in early pregnancy eventually leads to the formation of the definitive placenta. Physiological features of placentation that are essential to normal pregnancy and foetal development include modulation of immune responses at the placental interface, increasing placental bloodflow to allow for increasing foetal demand and the secretion of hormones for the recognition and maintenance of pregnancy. Descriptions of the morphology of the near-term placenta in a normal pregnancy and of the foetal membranes that are voided during normal parturition provide the proper context for understanding the morphological changes associated with placentitis and how these changes are likely to affect placental function.

One hundred (25%) of 400 cattle on a feedlot unit were affected with a sudden-onset lameness over a period of six weeks. The condition was seen in bulls, heifers and bullocks. Typically, one or two cattle in a pen of 20 presented with severe lameness; within 72 hours up to half of the cattle in the pen were similarly affected. The first eases to occur were treated with topical and systemic oxytetracyclines, tylosin and penicillin and streptomycin. However, the response to treatment was poor and, because of rapid weight loss, a decision was made to cull all affected cattle as they presented.The condition in any particular animal usually involved a single limb, either fore or hind, and affected animals exhibited a marked reluctance to bear weight on the limb involved. There was swelling of the coronary band, fissuring of the interdigital skin and development of granulation tissue within the fissures. Spirochaetes were demonstrated on examination of direct smears made from the lesions and Bacteroides melaninogenicus (prevotella melaninogenica) was isolated on cultural examination. The histopathological characteristics associated with the condition included a widespread keratinocyte degeneration within which were present variably-sized bright eosinophilic intracytoplasmic inclusion bodies. Ultrastructural examination of these inclusions suggested that they consisted of amorphous intracytoplasmic debris; viral particles could not be identified. Attempts to demonstrate virus on electron microscopic examination of negatively-stained preparations made from lesions and attempts to culture virus from all lesions were unsuccessful. However, numerous spirochaetes were present within the cytoplasm of affected keratinocytes; a role for these organisms in the aetiology of this condition seems likely.

An eighteen-month-old steer was presented with sudden-onset, progressively worsening ataxia. Cerebellar involvement was suspected on clinical grounds and a diagnosis of cerebellar medulloblastoma was made on post mortem examination. The occurrence of such a tumour in a bovine animal of more than one year of age has not been reported before.

One quarter of all the cattle on a feedlot unit containing 400 animals became affected with a sudden-onset lameness over a period of six weeks from the beginning of March 1995. The condition was seen in bulls, heifers and bullocks. Typically, one or two cattle in a pen of 20 presented with severe lameness; within 72 hours up to half of the cattle in the pen were similarly affected. The first case to occur were treated with topical and systemic oxytetracyclines, tylosin and penicillin and streptomycin. However, the response to treatment was poor and because of rapid weight loss, a decision was made in mid-March to cull all affected cattle as they presented. The condition in any particular animal usually involved a single Limb, either fore or hind, and affected animals exhibited a marked reluctance to bear weight on the limb involved. There was swelling of the coronary band, fissuring of the interdigital skin and development of granulation tissue within the fissures. Spirochaetes were demonstrated on examination of direct smears made from the lesions and Bacteroides melaninogenicus was isolated on cultural examination. The histopathological characteristics associated with the condition included a widespread keratinocyte degeneration within which were present variably-sized bright eosinophilic intracytoplasmic inclusion bodies. Ultrastructural examination of these inclusions suggested that they consisted of amorphous intracytoplasmic debris; no viral particles could be identified. However, numerous spirochaetes were present within the cytoplasm of affected keratinocytes. Attempts to demonstrate virus on electron microscopic examination of negatively-stained preparations made from lesions and attempts to culture virus from all lesions were all unsuccessful. The presence of numerous intracellular spirochaete-like organisms suggests a likely role in the aetiology of this condition.