Isabelle Truyers

Eradication programme for bovine viral diarrhoea virus in Orkney 2001 to 2008

The strategies used and the results obtained in Orkneys bovine viral diarrhoea virus (BVDV) eradication programme over eight years (2001 to 2008) are presented and discussed. The venture was undertaken by local veterinary practices and the Orkney Livestock Association (OLA) with the financial support of the Orkney Islands Council. Participation is voluntary; the programme comprises screening of youngstock, a whole-herd test if required, elimination of persistently infected animals and strict biosecurity measures and/or vaccination. BVDV-free herds are certified, and certification is updated annually by retesting the youngstock. The programme aims to minimise economic losses, thereby increasing the competitiveness of the Orcadian cattle industry and to improve animal health and welfare by eliminating virus circulation. Information from databases of the Scottish Agricultural College, Biobest Laboratories and OLA show that despite a significant reduction in the overall prevalence of BVDV on Orkney during the initial stages of the eradication programme, there has been little progress made since 2006 and that some difficulties have been encountered, with herd BVDV breakdowns following initial eradication. These results highlight the need for continued motivation of farmers, strict application of biosecurity measures and/or systematic vaccination of all seronegative breeding animals.

Identification of the 1B vaccine strain of Chlamydia abortus in aborted placentas during the investigation of toxaemic and systemic disease in sheep

CASE HISTORY: One hundred and forty Cheviot and 100 Suffolk cross Mule primiparous 1–2-year-old ewes, from a flock of about 700 ewes, were vaccinated with an attenuated live 1B strain Chlamydia abortus vaccine about 4 weeks before ram introduction (September 2011). Between 08 March and 01 April 2012, 50 2-year-old ewes aborted and 29 of these died, despite antimicrobial and anti-inflammatory treatment and supportive care. PATHOLOGICAL FINDINGS: Seven fetuses and three placentae from five 2-year-old ewes were submitted for pathological investigation. The aborted fetuses showed stages of autolysis ranging from being moderately fresh to putrefaction. Unusual, large multifocal regions of thickened membranes, with a dull red granular surface and moderate amounts of grey-white surface exudate were seen on each of the placentae. Intracellular, magenta-staining, acid fast inclusions were identified in Ziehl Neelsen-stained placental smears. Immunohistochemistry for Chlamydia-specific lipopolysaccharide showed extensive positive labelling of the placental epithelia. LABORATORY FINDINGS: Molecular analyses of the aborted placentae demonstrated the presence of the 1B vaccine-type strain of C. abortus and absence of any wild-type field strain. The vaccine strain bacterial load of the placental tissue samples was consistent with there being an association between vaccination and abortion. DIAGNOSIS: Initial laboratory investigations resulted in a diagnosis of chlamydial abortion. Further investigations led to the identification of the 1B vaccine strain of C. abortus in material from all three of the submitted aborted placentae. CLINICAL RELEVANCE: Timely knowledge and understanding of any potential problems caused by vaccination against C. abortus are prerequisites for sustainable control of chlamydial abortion. This report describes the investigation of an atypical abortion storm in sheep, and describes the identification of the 1B vaccine strain of C. abortus in products of abortion. The significance of this novel putative association between the vaccine strain of C. abortus and severe clinical disease is unknown. Aspects of the approach that is described are relevant to the investigation of all outbreaks of ovine abortion, irrespective of the diagnosis. Awareness of the changing role of C. abortus as a major global cause of abortion ought to reinforce the importance of monitoring of adequate biosecurity in those countries which are currently free from chlamydial abortion.

Distinct Campylobacter fetus lineages adapted as livestock pathogens and human pathobionts in the intestinal microbiota.

Campylobacter fetus is a venereal pathogen of cattle and sheep, and an opportunistic human pathogen. It is often assumed that C. fetus infection occurs in humans as a zoonosis through food chain transmission. Here we show that mammalian C. fetus consists of distinct evolutionary lineages, primarily associated with either human or bovine hosts. We use whole-genome phylogenetics on 182 strains from 17 countries to provide evidence that C. fetus may have originated in humans around 10,500 years ago and may have “jumped” into cattle during the livestock domestication period. We detect C. fetus genomes in 8% of healthy human fecal metagenomes, where the human-associated lineages are the dominant type (78%). Thus, our work suggests that C. fetus is an unappreciated human intestinal pathobiont likely spread by human to human transmission. This genome-based evolutionary framework will facilitate C. fetus epidemiology research and the development of improved molecular diagnostics and prevention schemes for this neglected pathogen.Human infections with Campylobacter fetus are often assumed to be derived from livestock. Here, Iraola et al. provide evidence that healthy humans may act as carriers and dispersers, and C. fetus may have originated in humans as an intestinal pathobiont and then adapted as a livestock pathogen.

Diagnosis and management of venereal campylobacteriosis in beef cattle.

BackgroundBovine venereal campylobacteriosis is caused by Campylobacter fetus subsp. venerealis and its glycerine-tolerant variant Campylobacter fetus subsp. venerealis biovars intermedius. The disease can be economically important when present in cattle herds, causing poor reproductive performance, embryo mortality and abortion. Sensitive and specific diagnostic tests are required in the diagnosis of infection and to inform and monitor disease control. Current tests include bacterial culture and fluorescent antibody testing of preputial sheath washings and an enzyme-linked immunosorbent assay and an agglutination test on vaginal mucus, although the predictive values of these tests can be inadequate in field investigations.Artificial insemination is often considered as a simple control method for bovine venereal campylobacteriosis, but is impractical for many beef suckler herds where breeding takes place at pasture. Commercial vaccines are unavailable in the UK, while the efficacy of autogenous vaccines using a bacterial isolate from infected animals on a specific farm is at best unproven. Hence, for some infected herds, the development of an alternative control strategy based on segregation of potentially infected and uninfected animals in combination with culling or treatment would be desirable. This approach requires meticulous records and herd health management.Case presentationIn this paper we highlight difficulties in diagnosing bovine venereal campylobacteriosis and demonstrate the benefits of good record keeping when investigating poor reproductive performance in a beef suckler herd and establishing a herd-specific approach to bio-containment of the infectious cause.ConclusionsBovine venereal campylobacteriosis is an economically important disease that should be considered in investigations of suckler herd subfertility problems. Control of the disease based on segregation of potentially infected and uninfected animals in combination with extensive culling can be achieved without the use of artificial insemination or vaccination, but requires meticulous records and strict adherence to herd biosecurity practices.

The value of trans-scrotal ultrasonography at bull breeding soundness evaluation (BBSE): The relationship between testicular parenchymal pixel intensity and semen quality

Bull breeding soundness evaluation (BBSE) is commonly undertaken to identify bulls that are potentially unfit for use as breeding sires. Various studies worldwide have found that approximately 20% of the bulls fail their routine prebreeding BBSE and are therefore considered subfertile. Multiple articles describe the use of testicular ultrasound as a noninvasive aid in the identification of specific testicular and epididymal lesions. Two previous studies have hypothesized a correlation between ultrasonographic testicular parenchymal pixel intensity (PI) and semen quality; however to date, no published studies have specifically examined this link. The aim of this study, therefore, was to assess the relationship between testicular parenchymal PI (measured using trans-scrotal ultrasonography) and semen quality (measured at BBSE), and the usefulness of testicular ultrasonography as an aid in predicting future fertility in bulls, in particular those that are deemed subfertile at the first examination. A total of 162 bulls from 35 farms in the South East of Scotland were submitted to routine BBSE and testicular ultrasonography between March and May 2014, and March and May 2015. Thirty-three animals failed their initial examination (BBSE1) due to poor semen quality, and were re-examined (BBSE2) 6 to 8 weeks later. Computer-aided image analysis and gross visual lesion scoring were performed on all ultrasonograms, and results were compared to semen quality at BBSE1 and BBSE2. The PI measurements were practical and repeatable in a field setting, and although the results of this study did not highlight any biological correlation between semen quality at BBSE1 or BBSE2 and testicular PI, it did identify that gross visual lesion scoring of testicular images is comparable to computer analysis of PI (P < 0.001) in identifying animals suffering from gross testicular fibrosis.

Retinopathy and optic neuropathy following closantel treatment of ewes

An outbreak of sudden onset blindness subsequent to dosing with oral closantel affecting 1 per cent of a six hundred ewe flock was investigated. Clinical examination and histopathology both revealed features fully consistent with closantel toxicity despite the maximum dose received by the affected sheep not exceeding 14.5 mg/kg (recommended dose rate 10 mg/kg). The interval between dosing and the onset of clinical signs had been recorded accurately (minimum interval eight days) and was found to be longer than in previous reports.

Management and control of Johne's disease in beef suckler herds

Johnes disease is a progressive, chronic wasting disease of cattle caused by Mycobacterium avium subspecies paratuberculosis (MAP) that results in significant economic losses to the livestock industry and has a notable impact on animal health and welfare. In recent years, the industry has recognised that it has a responsibility to identify and use every tool available to reduce the impact of this disease in dairy herds, and best practice measures and on-farm strategies to do this are well documented. However, there is a lack of information available to farmers and vets on Johnes disease control in beef suckler herds. This article describes biosecurity measures, surveillance and testing strategies, and other key control measures that could be used to prevent the introduction of MAP into disease-free beef suckler herds. It also discusses effective strategies for controlling the disease in infected suckler herds using combined management measures aimed at reducing both the prevalence of existing infections and the incidence of new infections.

Clinical and pathological findings associated with bovine Thebesian vein anomalies

FIRST described by the 18th century anatomist Adam Christian Thebesius (1686-1732) ([Loukas and others 2008][1]), Thebesian veins comprise all small coronary veins that connect the chambers of the atria and ventricles with the coronary vessels (rather than via the coronary sinus), enabling