A. Schock

Mycobacterial disease in a population of 339 cats in Great Britain: II. Histopathology of 225 cases, and treatment and outcome of 184 cases

This study investigated 339 cases of feline mycobacterial infection, with histopathology findings from 225 cases, and treatment and outcome information from 184 cases. Tissue samples from cats with cutaneous lesions or suspicious masses at exploratory laparotomy were submitted to the Veterinary Laboratories Agency for mycobacterial culture over a 4-year period to December 2008. The study reviewed the files for information about histopathology, treatment and outcome, and blindly reviewed histopathological changes (including staining for acid-fast bacteria [AFB]) in a sub-set of 45 cases. When a cat is suspected of having a mycobacterial infection, accurate identification of the species involved helps to determine possible treatment options and prognosis. The study confirmed that histopathology and the presence of AFB are useful tools in the recognition of mycobacterial infection. Unfortunately, they did little to help determine the species of mycobacteria involved. The study identified a group of cats that were negative for AFB at the primary laboratory, but from which mycobacteria could be cultured; commonly Mycobacterium bovis or Mycobacterium microti. The study also identified a group of cats which where culture negative, despite typical signs of mycobacterial infection and positive AFB staining. Many cases responded favourably to treatment (56% of the cases where information was available), and many cats gained complete remission (42%). However, relapses were common (64%) and often followed by pulmonary and/or systemic spread that may have resulted from treatment with short courses of single drugs. This study shows that the diagnosis and treatment of feline mycobacteriosis is complex and challenging.

Coccidiosis in British alpacas (Vicugna pacos)

SEVERE intestinal disease associated with Eimeria punoensis, Eimeria lamae, Eimeria alpacae, Eimeria macusaniensis and Eimeria ivitaensis has been observed in South American camelids in the Americas and Australia (Guerrero and others 1971, Rosadio and Ameghino 1994, Cebra and others 2003, Lenghaus and others 2004, Palacios and others 2006). However, there is conflicting information about the pathogenicity of the various camelid Eimeria species. Experimental infection of one-month-old llama crias with E macusaniensis did not result in disease (Rohbeck and others 2003), whereas experimental infection of a six-month-old naive alpaca cria with E lamae resulted in haemorrhagic ileitis with diarrhoea, and death (Guerrero and others 1970). This short communication describes a case of coccidiosis in a 16-month-old, UK-born alpaca. The animal had been purchased at an auction four weeks previously, and was reported to have been found dead after a short period of restlessness. At postmortem examination, severe necrotising enteritis was observed (Fig 1). Histological examination of the small intestine detected multiple clumps of eosinophilic material on the mucosal surface, loss of enterocytes associated with large numbers of coccidial structures in the crypt epithelium, lamina propria and, less frequently, submucosa, including immature schizonts, macrogametes with up to 10 round, variably sized, eosinophilic inclusions, and pearshaped oocysts approximately 60 to 75 μm in length (Fig 2). Gram-positive, rod-shaped bacteria were present on the luminal surface. Faecal coccidial counts revealed 3450 oocysts per gram of faeces, subsequently speciated as 91 per cent E macusaniensis, 3 per cent E alpacae and 3 per cent E lamae. Clostridium perfringens α toxin was identified by ELISA in the small intestinal filtrate. The loss of architecture associated with the large numbers of coccidial structures in superficial as well as deep layers of the mucosa strongly suggested that the Eimeria species had caused disruption of the intestinal lining, predisposing to clostridial enterotoxaemia. Prompted by this confirmed case of coccidiosis in an adult alpaca, a review of Veterinary Investigation Diagnosis Analysis data and material received at Veterinary Laboratories Agency – Lasswade between 1999 and 2004 identified 54 recorded cases of coccidial infection in alpacas. Of the 35 animals where the age was recorded, six were crias less than two months of age, 14 were juveniles (two to 11 months) and 15 were adults (one year and older) (Table 1). In 19 cases where clinical signs had been recorded, they included diarrhoea in six cases, weight loss in six, death in five, nervous signs in one and sudden-onset weakness in one. Congestion of the small intestine was commonly observed, with some cases showing marked thickening of the enteric mucosa. Variable numbers of coccidial structures were seen in small intestinal tissue sections. Concomitant findings in 19 cases where details were recorded included bacterial enteritis in nine cases, hepatic lipidosis in five and paracentral necrotisVeterinary Record (2007) 160, 805-806

Genomic variations associated with attenuation in Mycobacterium avium subsp. paratuberculosis vaccine strains.

BackgroundMycobacterium avium subspecies paratuberculosis (MAP) whole cell vaccines have been widely used tools in the control of Johne’s disease in animals despite being unable to provide complete protection. Current vaccine strains derive from stocks created many decades ago; however their genotypes, underlying mechanisms and relative degree of their attenuation are largely unknown.ResultsUsing mouse virulence studies we confirm that MAP vaccine strains 316xa0F, II and 2e have diverse but clearly attenuated survival and persistence characteristics compared with wild type strains. Using a pan genomic microarray we characterise the genomic variations in a panel of vaccine strains sourced from stocks spanning over 40xa0years of maintenance. We describe multiple genomic variations specific for individual vaccine stocks in both deletion (26–32 Kbp) and tandem duplicated (11–40 Kbp) large variable genomic islands and insertion sequence copy numbers. We show individual differences suitable for diagnostic differentiation between vaccine and wild type genotypes and provide evidence for functionality of some of the deleted MAP-specific genes and their possible relation to attenuation.ConclusionsThis study shows how culture environments have influenced MAP genome diversity resulting in large tandem genomic duplications, deletions and transposable element activity. In combination with classical selective systematic subculture this has led to fixation of specific MAP genomic alterations in some vaccine strain lineages which link the resulting attenuated phenotypes with deficiencies in high reactive oxygen species handling.

Investigation into an outbreak of encephalomyelitis caused by a neuroinvasive porcine sapelovirus in the United Kingdom.

An outbreak of neurological disease in grower pigs characterised by ataxia and paraparesis was investigated in this study. The outbreak occurred 3-4 weeks post weaning in grower pigs which displayed signs of spinal cord damage progressing to recumbency. Pathology in the affected spinal cords and to a lesser extent in the brainstem was characterised by pronounced inflammation and neuronophagia in the grey matter. Molecular investigation using a pan-virus microarray identified a virus related to porcine sapelovirus (PSV) in the spinal cord of the two affected pigs examined. Analysis of 802 nucleotides of the virus polymerase gene showed the highest homology with those of viruses in the genus Sapelovirus of Picornaviridae. This PSV, strain G5, shared 91-93%, 67-69% and 63% nucleotide homology with porcine, simian and avian sapeloviruses, respectively. The nucleotide homology to other members of the Picornaviridae ranged from 41% to 62%. Furthermore, viral antigen was detected and co-localised in the spinal cord lesions of affected animals by an antibody known to react with PSV. In conclusion, clinical and laboratory observations of the diseased pigs in this outbreak are consistent with PSV-G5 being the causative agent. To the best of the authors knowledge, this is the first unequivocal report of polioencephalomyelitis in pigs by a neuroinvasive PSV in the United Kingdom.

Assessing virulence of vaccine strains of Mycobacterium avium subspecies paratuberculosis in a calf model

The purpose of this investigation was to characterise the virulence of two Mycobacterium avium subspecies paratuberculosis (M.a. paratuberculosis) vaccine strains and compare them with a recent virulent isolate in new born calves over a time course of 8 months post-inoculation. Paratuberculosis-free new born calves were inoculated orally with either a vaccine strain (2e or 316F) or a wild type strain (F13) of M.a. paratuberculosis. Blood and faecal samples were collected throughout the experiment to analyse immune responses to infection and assess faecal shedding of M.a. paratuberculosis. Tissue samples were taken at post-mortem for histological examination and bacteriological culture. Cell-mediated immune responses were measured using a Bovigam (CSL) interferon-gamma assay. At 20 weeks post-inoculation there was a significant increase in the cell-mediated immune responses in calves infected with the wild type strain relative to the two vaccine strains. Acid fast bacteria were detected in the faeces of calves in all three groups between 4 and 8 weeks post-inoculation. Histopathology was unrewarding in all three groups. M.a. paratuberculosis was recovered only from tissues of calves inoculated with the wild type strain. Therefore, it appeared that the vaccine strains used in this study had reduced virulence. Identifying the genes responsible for pathogenesis observed in the wild type isolate and reduced or inactive in these vaccine isolates may offer a valuable resource for improving our knowledge of pathogenesis and permit the development of improved diagnostic reagents and vaccines for the control of M.a. paratuberculosis in livestock.

Parvovirus enteritis in Eurasian badgers (Meles meles).

A number of potential enteropathogens have been identified in Eurasian badgers in Great Britain. These include protozoa such as Eimeria melis , Isospora melis (Anwar and others 2000) and Giardia species (Barlow and others 2011), Helminths (Hancox 1980, Jones and others 1980), and salmonellae (Wray and others 1977, Euden 1990, Wilson and others 2003). However, no viral enteropathogens have been confirmed in Great Britain or throughout the range of the Eurasian badger. Histopathological findings suggestive of parvovirus enteritis have been seen in cases of diarrhoea in captive, hand-reared badgers. However, the presence of parvovirus has never been confirmed by laboratory means in these cases (Mullineaux 2003). Parvovirus infection has also been suspected as the cause of myocarditis in a Eurasian badger (Burtscher and Url 2007). This again was based only on histological findings, as there was no parvoviral antibody or antigen confirmation. This communication describes parvovirus infection causing enteric pathology associated with acute diarrhoea and death in badger cubs.nnFive badger cubs, about 20 weeks of age, at a wildlife centre died with acute severe diarrhoea in a two-week period despite therapy and supportive treatment. Initially, three carcases were submitted to the Veterinary Laboratories Agency (VLA) - Langford for postmortem examination. These had been at the wildlife centre between one and two and a half months. Two were from Somerset and the most recent arrival was from Essex. These were all in fair bodily condition but were dehydrated. All had empty stomachs and in one cub the small and …

Laboratory diagnosis of Mycoplasma/Ureaplasma abortion in cattle.

WE would like to report the findings from six cases of suspected Mycoplasma/Ureaplasma -associated abortion. The cases occurred between April 2009 and July 2011; five cases were diagnosed at AHVLA – Penrith and one at SAC Dumfries. From analysis of VIDA (Veterinary Investigation Surveillance Report) data, these are the only diagnoses in England, Wales and Scotland of Mycoplasma/Ureaplasma abortion during this period. The purpose of this letter is to raise awareness of Mycoplasma/Ureaplasma -associated abortion and the range of samples required to facilitate its laboratory diagnosis by the AHVLA and the SAC.nnThe laboratory diagnosis of bovine abortion has a diagnostic rate of approximately 50 per cent. The range and quality of the samples submitted has a significant effect on the testing protocol. Commonly, the lack of an adequate placental sample prevents any assessment of the presence or absence of placentitis and the demonstration of agents such as Chlamydophila species or Coxiella burnetii (Q fever), which require placental smears.nnSometimes a full range of abortion samples is submitted and the laboratory diagnostician is frustrated by the demonstration of placentitis, but with no causative …

Cerebral segmental polyarteritis of unknown aetiology in sheep.

Vasculitis affecting the meningeal elastic arteries was identified in six sheep of various breeds during routine diagnostic investigation. The lesions consisted of multifocal intimal proliferation, thickening of the tunica media, multifocal infiltration of the media by inflammatory cells and more extensive perivascular accumulation of lymphocytes and plasma cells within the tunica adventitia. Fibrinoid necrosis affected an intergyral artery in one sheep. Immunohistochemistry failed to demonstrate pestivirus antigen associated with the lesions and no alternative aetiology was defined. Possible causes of meningeal segmental polyarteritis in sheep are discussed.

Fibromatous lesions of antler velvet and haired skin in reindeer (Rangifer tarandus)

Fibromatous nodular lesions were observed on the antler skin of reindeer from four separate farms, and from the haired skin from a deer from a fifth farm. The aim of this study was to investigate if the proliferative lesions represented an unusual manifestation of a viral infection. Despite extensive investigations using immunohistochemistry, PCR and electron microscopy, no evidence of viral involvement could be demonstrated. The aetiology of the lesions remains unknown.nnFibropapillomas are nodular or plaque-like lesions associated with papilloma virus (PV) infection; they have been observed in several deer species, including reindeer (Sundberg and Nielsen 1981, Ginn and others 2007). The histopathological findings typically include proliferation of dermal fibroblasts. Reindeer papilloma virus (RtPV1) has been detected in papillomatous lesions involving the haired skin of reindeer (Narechania and others 2004). In this report, we describe fibrous proliferation of the dermis of lesions involving the antler velvet and haired skin of reindeer from several farms; despite various investigations, PV was not detected, and the aetiology of the lesions was not determined.nnBetween 2009 and 2012, case material from five British farms with small groups of reindeer was submitted to five regional laboratories of the Animal Health and Veterinary Laboratories Agency (AHVLA) for diagnostic investigation as part of the AHVLA New and Emerging Disease Programme.nnThe first case was a five-year-old castrated reindeer with multiple plaques, crusts and draining sinuses involving the haired skin of the distal hindlimbs (Figxa01). The lesions spontaneously resolved 18u2005months after presentation; one in-contact deer was unaffected. Samples were submitted from a second case from a farm with a herd of 10 castrated males of which six had variable numbers of lesions involving the antler velvet observed over a two-year period. The lesions consisted of multiple fleshy nodules with some ulceration and crusting. On a third farm, three …

Pericardial Myxoid Liposarcoma in a Common Eland (Taurotragus oryx)

A pericardial myxoid liposarcoma was diagnosed in a common eland (Taurotragus oryx) based on gross, microscopical and immunohistochemical findings. The pericardial and epicardial tissues were soft and uniformly thickened. Microscopically, the neoplastic mass consisted of stellate cells embedded in a myxoid matrix. These cells contained cytoplasmic vacuoles stained by oil red O. Immunohistochemical analysis showed the neoplastic cells to express vimentin and S-100.