Bluetongue disease in sheep in New South Wales - April 2023.

In 2016, bluetongue virus (BTV), serotype 16 (BTV-16), was detected in New South Wales (NSW) in sentinel cattle for the first time. Over the next 6 years, BTV-16 has been detected regularly and over an increasing area of the BTV zone in NSW. In April 2023, disease was reported in sheep on two farms on the Northern Tablelands of NSW. The consistent clinical signs included reduced exercise tolerance, facial swelling, serous nasal discharges with encrustation of the nasal plane, subcutaneous oedema of the neck and brisket and variable congestion of the coronary band. Affected sheep were mainly mature ewes and rams, with an estimated morbidity of 20% over a period of 6-8 weeks. Although there were several unexpected deaths, no veterinary examination was sought. Predominantly BTV-16 RNA was detected in sick sheep, with an incidence of infection of approximately 40% in a cross section of one flock. These events represent the first confirmation of disease due to bluetongue virus in NSW. As these cases occurred in a region with a high density of sheep, if there is ongoing transmission of BTV-16 during subsequent summers, further disease might be expected.

An investigation into the transmission and control of pestivirus in sheep in Australia.

Border disease virus (BDV) is a member of the pestivirus genus that primarily affects sheep, causing reproductive losses through abortion, still births and the birth of weak lambs. The key characteristic of this disease is the birth of persistently infected (PI) lambs which, after surviving transplacental infection, are born antibody negative, yet virus positive, and thus shed the virus for their entire life and are the primary source of spread within a flock. The cornerstones of BDV control are detection and elimination of PI animals, biosecurity measures to prevent re-infection, and surveillance programs. Recommendations for the control of BDV in sheep are centred around the approach to bovine viral diarrhoea virus (BVDV), the prominent cattle pestivirus species, due to a lack of specific research into BDV control and elimination. In this study, two aspects of a BDV control program were investigated: the effectiveness of the BVDV vaccine, Pestigard®, and the rate of seroconversion in a flock deliberately exposed to known PI lambs. The vaccine appeared to be safe, and the optimal dose was the full cattle dose (2 mL). While vaccination induced high virus neutralising titres to BVDV when administered as either a quarter, half or full dose registered for cattle, the BDV titres achieved were low and unlikely to prevent transplacental infection. In a second study, after exposure of between 2 and 15 days exposure to two PI lambs in confined conditions, only 3 of 66 previously naïve sheep demonstrated seroconversion. This demonstrated a very low rate of transmission and suggested that deliberate exposure to PI lambs at low-risk times for less than 15 days was not likely to be an effective means of achieving seroconversion throughout a flock and, therefore, not provide protection against BDV challenge during gestation.

The potential for bluetongue virus serotype 16 to cause disease in sheep in New South Wales, Australia.

BLUETONGUE VIRUS SEROTYPE 16 DETECTION IN NSW: In coastal New South Wales (NSW), bluetongue virus (BTV) serotypes 1 and 21 are endemic and transmitted in most years without evidence of disease. However, serotype 16 (BTV-16) infection was detected for the first time in NSW in November 2016 in cattle undergoing testing for export. Retrospective testing of blood samples collected from sentinel cattle as part of the National Arbovirus Monitoring Program (NAMP) established that the first detected transmission of BTV-16 in NSW occurred in April 2016 in sentinel cattle on the NSW North Coast. Subsequently, until 2022, BTV-16 has been transmitted in most years and was the predominant serotype in the 2018-2019 transmission season. The data available suggests that BTV-16 may have become endemic in NSW. EXPERIMENTAL STUDIES: During experimental infection studies with BTV-16, all sheep were febrile, with the peak of viremia occurring 6-10 days after inoculation. There was nasal and oral hyperaemia in most sheep with several animals developing a nasal discharge and nasal oedema. All sheep developed coronitis of varying severity, with most also developing haemorrhages along the coronary band. There was a high incidence of haemorrhage in the pulmonary artery, epicardial petechiae, extensive pericardial haemorrhages and moderate body cavity effusions including pericardial effusions. CONCLUSION: Overall, experimental pathogenicity findings suggest moderate disease may occur in sheep in the field. These findings, when combined with climatic variability that could result in an expansion of the range of Culicoides brevitarsis into major sheep-producing areas of the state, suggest that there is an increasing risk of bluetongue disease in NSW.

Ostreid herpesvirus-1 microvariant surveillance in Pacific oysters (Magallana gigas, Thunberg, 1793) in Australia in 2011.

OBJECTIVE: To demonstrate that OsHV-1 microvariant was limited to the known infected areas in New South Wales at the time of the survey in 2011. DESIGN: A 2-stage survey to demonstrate probability of infection at 2% design prevalence within oyster growing regions and to detect at least one infected region (4% design prevalence) with 95% confidence. SAMPLE POPULATION: Magallana gigas in nominated oyster growing regions in New South Wales, South Australia and Tasmania as approved by the Aquatic Consultative Committee on Emergency Animal Diseases and documented in a national surveillance plan. PROCEDURE: Field sampling for active surveillance and laboratory selection of appropriate tissues using methods to minimize potential for cross contamination. Published methods for qPCR and conventional PCR for OsHV-1 microvariant. Stochastic analysis of survey results to demonstrate probability of detection in the areas tested. RESULTS AND CONCLUSIONS: OsHV-1 microvariant was not detected in a total 4121 samples according to the case definition developed for the survey. However, in NSW a screening qPCR for OsHV-1 detected 13 samples that reacted. These samples were negative at 2 laboratories in the qPCR and conventional PCR assays used in the case definition for the survey. We concluded that oyster production areas of Australia outside the infected area in NSW met the criteria for self-declaration of freedom at the time of the survey in 2011. CLINICAL RELEVANCE: This activity illustrated achievements in surveillance for an emerging emergency animal pathogen where epidemiological and test validation data were limited, but where data was required to inform the emergency disease response. It also illustrated the challenges faced by investigators in interpreting surveillance results using tests with limited validation. It was guided by and has informed improvements in surveillance and emergency disease preparedness.

What can we learn from over a decade of testing bats in New South Wales to exclude infection with Australian bat lyssaviruses?

Australian Bat lyssaviruses (ABLV) are known to be endemic in bats in New South Wales (NSW), Australia. These viruses pose a public health risk because they cause a fatal disease in humans that is indistinguishable from classical rabies infection. All potentially infectious contact between bats and humans, or between bats and domestic animals, should be investigated to assess the risk of virus transmission by submitting the bat for testing to exclude ABLV infection. The aim of this study was to establish the prevalence of ABLV infection in bats submitted for testing in NSW and to document any trends or changes in submission and bat details. We examined all submissions of samples for ABLV testing received by the NSW Department of Primary Industries Virology Laboratory for the 13-year period between 1 May 2008 and 30 April 2021. Fifty-four (4.9%) ABLV-infected bats were detected, with some clustering of positive results. This is greater than the prevalence estimated from wild-caught bats. All bats should be considered a potential source of ABLV. In particular, flying-foxes with rabies-like clinical signs, and with known or possible human interaction, pose the highest public health risk because they are more likely to return a positive result for ABLV infection. This review of ABLV cases in NSW will help veterinarians to recognise the clinical presentations of ABLV infection in bats and emphasises the importance of adequate rabies vaccination for veterinarians.

Your assay has changed - is it still 'fit for purpose'? What evaluation is required.

A reliable laboratory assay is an essential tool for the diagnosis or surveillance of most animal diseases. Before routine use, assays should be appropriately validated to ensure that they have performance characteristics that provide reliable results and can be used for the intended purpose. It is inevitable that, over time, changes will need to be made to assay reagents, to the assay format, to test a different species or for implementation in a new laboratory. Whenever there is a change (whether it be components, application or location), it is essential to establish whether the new circumstances affect the biological basis and properties of the assay. If the modifications do not affect the biological basis of the assay, the changes might be considered minor and a verification study can be conducted to confirm that the performance characteristics have not been adversely affected. Major changes require a new validation to be carried out. A method comparability study, where original and modified assays are run concurrently to test the same sample panel, provides an extremely robust comparison. However, comparability studies are not always an option, especially for the introduction of a method to a new laboratory. Access to original validation data and suitable reference sample panels then becomes essential to provide evidence that the assay remains 'fit for the intended purpose'.

Les essais de laboratoire fiables constituent des outils essentiels pour le diagnostic ou la surveillance d'une majorité de maladies animales. Avant d'être utilisés en routine, les essais doivent faire l'objet d'une validation appropriée, destinée à s'assurer qu'ils possèdent les caractéristiques de performance nécessaires pour générer des résultats fiables et à déterminer qu'ils peuvent être utilisés pour la finalité prévue. Au fil du temps, il est inévitable que certains changements soient apportés aux réactifs de l'essai ou à son format, visant par exemple à appliquer le test sur autre espèce animale ou dans un nouveau laboratoire. À chaque changement introduit (qu'il s'agisse d'une composante du test, de sa modalité d'application ou du lieu où il est conduit), il est essentiel de déterminer si ces nouvelles circonstances affectent la base biologique et les propriétés de l'essai. Si les modifications n'affectent pas la base biologique de l'essai, les changements peuvent être considérés comme mineurs et une étude de contrôle des performances pourra être réalisée pour confirmer que les caractéristiques de performance n'ont pas subi d'altération indésirable. En cas de changement majeur, une nouvelle étude de validation devra être réalisée. L'étude de comparabilité de méthodes, qui consiste à réaliser simultanément l'essai original et l'essai modifié sur un même panel d'échantillons fournit une comparaison extrêmement robuste. Néanmoins, dans certaines situations les études de comparabilité ne sont pas une option, notamment lorsqu'il s'agit d'introduire la méthode modifiée dans un nouveau laboratoire. Il devient alors indispensable de pouvoir accéder aux données de validation originales et de disposer de panels d'échantillons de référence appropriés afin de fournir la preuve que l'essai est toujours « apte à l'emploi ¼ qui lui a été assigné.

Un ensayo de laboratorio fiable es una herramienta básica para el diagnóstico o la vigilancia de la mayoría de las enfermedades animales. Antes de poder emplear de forma sistemática un ensayo es preciso validarlo debidamente, para tener la seguridad de que presente características de rendimiento adecuadas, que deparen resultados fiables, y de que se ajuste al propósito previsto. Con el tiempo, inevitablemente, será preciso modificar los reactivos y el formato del ensayo, con objeto de aplicarlo a una especie diferente o de practicarlo en un nuevo laboratorio. Siempre que haya un cambio en el ensayo (ya sea en sus componentes o en su modo o lugar de aplicación), será esencial determinar si las nuevas circunstancias influyen en su base biológica o en sus propiedades. Cuando las modificaciones no incidan en su base biológica, se podrá considerar que los cambios son de importancia menor y se podrá realizar un estudio de verificación para comprobar que las características de rendimiento no se han visto negativamente afectadas. Los cambios de mayor entidad exigen un nuevo proceso de validación. Los estudios de comparación de métodos, en los que paralelamente se aplican la técnica original y la modificada a un mismo panel de muestras, deparan una comparación sumamente robusta. Sin embargo, los estudios de comparabilidad no siempre son una posibilidad factible, sobre todo cuando se trata de empezar a aplicar un método en un nuevo laboratorio. En tales casos resultará fundamental tener acceso a los datos de validación originales y a paneles adecuados de muestras de referencia para asegurarse de que el ensayo siga siendo 'idóneo para el propósito previsto'.

Encephalomyocarditis virus infection in alpacas.

Encephalomyocarditis virus (EMCV) infection was detected by real-time reverse transcription PCR (qRT-PCR) in four adult alpacas (Vicugna pacos) from two properties on the Far North Coast of New South Wales (NSW) in April and May 2018 and in two adult alpacas from a third property on the Central Coast of NSW in October 2018. Viral RNA was detected in a range of samples, including blood, fresh body organs and mucosal swabs. EMCV was isolated from the blood and body organs of five of these alpacas. These animals displayed a range of clinical signs, including inappetence, colic, recumbency and death. Necropsy findings included multifocal to coalescing areas of myocardial pallor, pulmonary congestion and oedema, hepatic congestion and serosal effusion. Histopathological changes comprised acute, multifocal myocardial degeneration and necrosis, with mild, neutrophilic and lymphocytic inflammation (5/5 hearts) and mild, perivascular neutrophilic meningoencephalitis (1/3 brains). This is the first report of disease due to EMCV in alpacas under farm conditions, and it identifies EMCV infection as a differential diagnosis for acute disease and death in this camelid species. In addition to the samples traditionally preferred for EMCV isolation (fresh heart, brain and spleen), blood samples are also appropriate for EMCV detection by qRT-PCR assay.

Clinical and epidemiological features of West Nile virus equine encephalitis in New South Wales, Australia, 2011.

BACKGROUND: Between February and June 2011, more than 300 horses with unexplained neurological disease were observed in New South Wales, Australia. A virulent strain of West Nile virus (WNVNSW2011 ), of Australian origin, was shown to be the cause of many of these cases. METHODS: We reviewed the clinical descriptions provided by veterinary practitioners and the associated laboratory results. Although there was a range of clinical signs described, ataxia was the only sign that was consistently described in laboratory-confirmed cases. RESULTS: WNV was detected in brain samples by real-time reverse transcription PCR assay and virus isolation. For serological confirmation of clinical cases, an equine IgM ELISA specific for WNV was shown to be the most effective tool. CONCLUSION: A state-wide serological survey undertaken after the outbreak indicated that, contrary to expectation, although infection had been widespread, the seroprevalence of antibodies to WNV was very low, suggesting that there could be a significant risk of future disease outbreaks.

Efficacy of a commercial vaccine against different strains of rabbit haemorrhagic disease virus.

BACKGROUND: This study investigated the ability of a commercial rabbit haemorrhagic disease virus (RHDV) vaccine (Cylap®) to protect rabbits from disease caused by two different strains of the virus (v351 and K5) that are used or proposed to be used for wild rabbit control in Australia. These strains of the RHDV1 genotype belong to the 'classical RHDV' and 'antigenic variant RHDVa' subtypes, respectively. METHODS: Vaccinated rabbits were exposed to very high doses of the virus either by direct oral dosing or by exposure to infected rabbit livers. RESULTS & CONCLUSION: All vaccinated rabbits were protected against rabbit haemorrhagic disease, indicating that the Cylap® vaccine is effective against both strains of the virus under experimental conditions.

Application of an embryonated chicken egg model to assess the vector competence of Australian Culicoides midges for bluetongue viruses.

Culicoides biting midges (Diptera: Ceratopogonidae) are vectors of a number of globally important arboviruses that affect livestock, including bluetongue virus (BTV), African horse sickness virus and the recently emerged Schmallenberg virus. In this study, a model using embryonated chicken eggs (ECEs) was utilized to undertake vector competence studies of Australian Culicoides spp. for 13 laboratory-adapted or wild-type virus strains of BTV. A total of 7393 Culicoides brevitarsis were reared from bovine dung, and 3364 Culicoides were induced to feed from ECEs infected with different strains of BTV. Of those, 911 (27%) survived the putative extrinsic incubation period of 9-12 days. In some trials, virus was also transmitted onward to uninfected ECEs, completing the transmission cycle. This model does not rely on the use of colonized midges and has the capacity to assess the vector competence of field-collected insects with strains of virus that have not previously been passaged in laboratory culture systems. There is also potential for this model to be used in investigations of the competence of Culicoides spp. for other arboviruses.

Neospora caninum in beef herds in New South Wales, Australia. 2: analysis of risk factors.

OBJECTIVE: To determine the influence of farm-level and animal-level factors on the seroprevalence of antibodies to Neospora caninum and associations between seropositivity and reproductive outcomes. METHODS: A questionnaire for a cross-sectional survey was posted to the 63 properties with a herd size ≥50 beef breeding cows that had participated in a previous seroprevalence study. Correspondence analysis, which does not appear to have been used previously in any Australian studies of livestock diseases, was used in conjunction with logistic regression to analyse the data. RESULTS: Geographic factors that increased the risk of seropositivity included higher rainfall North Coast location. Herd management factors that increased the risk of seropositivity included the use of Bos indicus genetics, cross-breeding and running several breeds in the one herd. Using fox control measures was found to be protective against infection with N. caninum. The risk of abortion was 12-fold greater in individual animals that were seropositive for N. caninum. Within a herd, the calving rate was 10.4% lower in herds with one or more N. caninum-positive animals (P = 0.03), but the difference in abortion rate was not significant between seropositive and seronegative herds (0.3% higher, P > 0.3). CONCLUSIONS: This study confirmed previous observations of increased risks for N. caninum seropositivity with being located in the coastal subtropics, some styles of herd management and canid exposure. In addition, it suggested that cross-breeding and proximity to an urban area may increase the risk, and that having pet dogs may reduce the risk of seropositivity.

Neospora caninum in beef herds in New South Wales, Australia. 1: seroprevalence study.

OBJECTIVE: To determine the seroprevalence of Neospora caninum antibodies in beef breeding herds across New South Wales (NSW) and to determine if there are any differences associated with geographic location and other herd-level factors. METHODS: Cross-sectional survey of beef breeding cows (n = 3298) from 63 properties (approximately 55 cows per herd) sampled randomly from six regions in NSW using a multistage survey design. Samples were tested by ELISA for N. caninum. Seroprevalence was determined at animal and herd levels, using an analysis approach to account for stratification, sample weighting and within-herd clustering. RESULTS: Animal-level seroprevalence ranged from 1.8% to 11.3% across regions and the overall animal seroprevalence for NSW was 5.9%. The mean within-herd seroprevalence was 5.2%. The herd seroprevalence ranged from 50% to 92%, with an overall point estimate for NSW of 63.8% (using ≥ 1 animal positive = herd positive). The within-herd seroprevalence ranged from 1.6% to 32.7% Prevalence and associated confidence limits were adjusted for the design of the survey. CONCLUSIONS: Overall, about two-thirds of all herds in NSW showed evidence of infection, but the seroprevalence of N. caninum in individual beef cattle in NSW was low to moderate (1.8-11.3%). Significant differences occurred between regions. The risk for herds being positive for N. caninum was associated with geographic factors, particularly in the Mid-North Coast Region.

Development and evaluation of real-time PCR assays for bloodmeal identification in Culicoides midges.

Culicoides (Diptera: Ceratopogonidae) midges are the biological vectors of a number of arboviruses of veterinary importance. However, knowledge relating to the basic biology of some species, including their host-feeding preferences, is limited. Identification of host-feeding preferences in haematophagous insects can help to elucidate the transmission dynamics of the arboviruses they may transmit. In this study, a series of semi-quantitative real-time polymerase chain reaction (qPCR) assays to identify the vertebrate host sources of bloodmeals of Culicoides midges was developed. Two pan-reactive species group and seven species-specific qPCR assays were developed and evaluated. The assays are quick to perform and less expensive than nucleic acid sequencing of bloodmeals. Using these assays, it was possible to rapidly test nearly 700 blood-fed midges of various species from several geographic locations in Australia.

Akabane virus infection.

Akabane virus is a Culicoides-borne orthobunyavirus that is teratogenic to the fetus of cattle and small ruminant species. Depending upon the stage of gestation atwhich infection occurs, and the length of gestation of the mammalian host, a range of congenital defects may be observed. The developing central nervous system is usually the most severely affected, with hydranencephaly and arthrogryposis most frequently observed. Less commonly, some strains of Akabane virus can cause encephalitis in the neonate or, rarely, adult cattle. Akabane viruses are known to be widespread in temperate and tropical regions of Australia, Southeast Asia, the Middle East and some African countries. Disease is infrequently observed in regions where this virus is endemic and the presence of the virus remains unrecognised in the absence of serological surveillance. In some Asian countries, vaccines are used to minimise the occurrence of disease.

Avian influenza in Australia: a summary of 5 years of wild bird surveillance.

BACKGROUND: Avian influenza viruses (AIVs) are found worldwide in numerous bird species, causing significant disease in gallinaceous poultry and occasionally other species. Surveillance of wild bird reservoirs provides an opportunity to add to the understanding of the epidemiology of AIVs. METHODS: This study examined key findings from the National Avian Influenza Wild Bird Surveillance Program over a 5-year period (July 2007-June 2012), the main source of information on AIVs circulating in Australia. RESULTS: The overall proportion of birds that tested positive for influenza A via PCR was 1.9 ± 0.1%, with evidence of widespread exposure of Australian wild birds to most low pathogenic avian influenza (LPAI) subtypes (H1-13, H16). LPAI H5 subtypes were found to be dominant and widespread during this 5-year period. CONCLUSION: Given Australia's isolation, both geographically and ecologically, it is important for Australia not to assume that the epidemiology of AIV from other geographic regions applies here. Despite all previous highly pathogenic avian influenza outbreaks in Australian poultry being attributed to H7 subtypes, widespread detection of H5 subtypes in wild birds may represent an ongoing risk to the Australian poultry industry.

Detection of serum neutralizing antibodies to Simbu sero-group viruses in cattle in Tanzania.

BACKGROUND: Orthobunyaviruses belonging to the Simbu sero-group occur worldwide, including the newly recognized Schmallenberg virus (SBV) in Europe. These viruses cause congenital malformations and reproductive losses in ruminants. Information on the presence of these viruses in Africa is scarce and the origin of SBV is unknown. The aim of this study was to investigate the presence of antibodies against SBV and closely related viruses in cattle in Tanzania, and their possible association with reproductive disorders. RESULTS: In a cross-sectional study, serum from 659 cattle from 202 herds collected in 2012/2013 were analyzed using a commercial kit for SBV ELISA, and 61 % were positive. Univariable logistic regression revealed significant association between ELISA seropositivity and reproductive disorders (OR = 1.9). Sera from the same area collected in 2008/2009, before the SBV epidemic in Europe, were also tested and 71 (54.6 %) of 130 were positive. To interpret the ELISA results, SBV virus neutralization test (VNT) was performed on 110 sera collected in 2012/2013, of which 51 % were positive. Of 71 sera from 2008/2009, 21 % were positive. To investigate potential cross reactivity with related viruses, 45 sera from 2012/2013 that were positive in SBV ELISA were analyzed in VNTs for Aino, Akabane, Douglas, Peaton, Sabo, SBV, Sathuperi, Shamonda, Simbu and Tinaroo viruses. All 45 sera were positive for one or more of these viruses. Twenty-nine sera (64.4 %) were positive for SBV, and one had the highest titer for this virus. CONCLUSIONS: This is the first indication that Aino, Akabane, Douglas, Peaton, Sabo, SBV, Sathuperi, Shamonda and Tinaroo viruses circulate and cause negative effect on reproductive performance in cattle in Tanzania. SBV or a closely related virus was present before the European epidemic. However, potential cross reactivity complicates the interpretation of serological studies in areas where several related viruses may circulate. Virus isolation and molecular characterization in cattle and/or vectors is recommended to further identify the viruses circulating in this region. However, isolation in cattle is difficult due to short viremic period of 2 to 6 days, and isolation in vectors does not necessarily reflect the situation in cattle.

Genetic and antigenic characterization of Bungowannah virus, a novel pestivirus.

Bungowannah virus, a possible new species within the genus Pestivirus, has been associated with a disease syndrome in pigs characterized by myocarditis with a high incidence of stillbirths. The current analysis of the whole-genome and antigenic properties of this virus confirms its unique identity, and further suggests that this virus is both genetically and antigenically remote from previously recognized pestiviruses. There was no evidence of reactivity with monoclonal antibodies (mAbs) that are generally considered to be pan-reactive with other viruses in the genus, and there was little cross reactivity with polyclonal sera. Subsequently, a set of novel mAbs has been generated which allow detection of Bungowannah virus. The combined data provide convincing evidence that Bungowannah virus is a member of the genus Pestivirus and should be officially recognized as a novel virus species.

Bungowannah virus--a probable new species of pestivirus--what have we found in the last 10 years?

Bungowannah virus was discovered following an outbreak of stillbirths and sudden death in young pigs. Affected animals consistently showed a myocardopathy with signs of cardiac failure. After virus isolation and PCR investigations were unsuccessful, direct fetal inoculation was undertaken. Nucleic acid purified from serum from infected fetuses was subjected to sequence-independent single-primer amplification and nucleic acid sequencing. Sequences consistent with a pestivirus were obtained. The entire genome was identified but was genetically remote from the recognized pestivirus species. This virus was not recognized by pan-pestivirus reactive monoclonal antibodies but was subsequently detected in cell cultures by immunoperoxidase staining using convalescent sow serum. Experimental infections of sows at different stages of gestation reproduced the myocarditis syndrome. Pre-weaning losses of 70 and 29% were observed following infection at days 35 and 90, respectively. Piglets infected at day 35 were shown to be persistently infected, while chronic infections were observed after fetal infection at day 55. Chronically infected piglets showed growth retardation and were viremic for up to 7 months. Myocarditis was associated with infection in late gestation (day 90). Non-pregnant sheep and cattle have been experimentally infected but with no evidence of disease. Infection of pregnant cattle in early gestation resulted in both maternal and fetal infection, but all infected fetuses mounted an antibody response to the virus. Analysis of the nucleic acid sequence confirmed that Bungowannah has a number of changes not observed in other pestiviruses. Genes encoding some of the structural proteins remain fully functional when inserted into a bovine viral diarrhea virus (BVDV) backbone. Cell culture-based studies have shown that Bungowannah virus will grow in cells extending from humans to bats as well as farm animals.

Application of a real-time polymerase chain reaction assay to the diagnosis of bovine ephemeral fever during an outbreak in New South Wales and northern Victoria in 2009-10.

OBJECTIVE: To report the occurrence of an epizootic of bovine ephemeral fever (BEF) in New South Wales (NSW) and northern Victoria in 2009-10 and describe the application of a real-time reverse transcription polymerase chain reaction (qRT-PCR) assay during the outbreak. PROCEDURES: Whole-blood samples from animals exhibiting clinical signs of BEF were requested from district veterinarians in NSW. In addition, samples were submitted from private practitioners in NSW and Victoria. In NSW, samples from animals showing acute clinical signs of BEF were tested using a qRT-PCR assay. Serological testing for BEF diagnosis was undertaken as required. Virus isolation was performed on selected samples in which bovine ephemeral fever virus (BEFV) RNA was detected. Archival serum samples and mosquito homogenates were also tested for BEFV by qRT-PCR. RESULTS: Accessions were received from 121 properties in NSW, with cases of BEF confirmed on 84 properties by qRT-PCR and 20 properties by serology. In northern Victoria, BEF was confirmed on 25 properties based on serological testing. Screening of samples by qRT-PCR enhanced the success of BEFV isolation. BEFV RNA was successfully detected in archival serum samples and a single mosquito homogenate. CONCLUSIONS: The 2009-10 outbreak resulted in the most extensive transmission of BEFV in NSW and Victoria since 1995-96, and follows a smaller outbreak in summer-autumn 2008. The use of qRT-PCR for BEF diagnosis offers veterinarians and cattle owners rapid confirmation of infection (1-2 days) and provides 'real-time' information about the presence of the disease in a district.