Neuropathological survey of fallen stock: Active surveillance reveals high prevalence of encephalitic listeriosis in small ruminants

Neurocenter & Clinical Research, Department of Clinical Research & VPH, Vetsuisse Faculty, University of Bern, Bremgartenstrasse 109a, Bern, Switzerland.
Veterinary Microbiology (Impact Factor: 2.73). 09/2008; 130(3-4):320-9. DOI: 10.1016/j.vetmic.2008.01.015
Source: PubMed

ABSTRACT This paper describes the prevalence of brain lesions in the Swiss fallen stock population of small ruminants. 3075 whole brains (75% sheep, 25% goats) were collected as part of a year-long active survey of transmissible spongiform encephalopathies (TSEs) in small ruminants conducted by the Swiss authorities between July 2004 and July 2005. All fallen stock brains were systematically examined by histopathology to obtain reliable data on histologically identifiable brain lesions. Lesions were found in an unexpectedly high number of animals (8.1% of all examined brains). A wide spectrum of diseases was detected showing that this approach provides an excellent opportunity to screen for the prevalence of neurological diseases. Encephalitic listeriosis was by far the most frequent cause of CNS lesions in both species and its prevalence was unexpectedly high when compared to notified confirmed cases. In conclusion, the prevalence of listeriosis as estimated by passive surveillance based on the notification of clinical suspects has been underestimated in the past.

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    ABSTRACT: Background The present study describes the pathologic changes in the brain and the spinal cord of aborted, stillbirth and deformities of newborn lambs infected with viral agents.Methods From February 2012 to March 2013, a total of 650 aborted fetuses from 793 pregnant ewes were studied from 8 flocks at different areas in the Mazandaran province in the north of Iran. And randomly, systematic necropsy was performed to collect tissues, and all gross abnormalities were recorded at necropsy by the pathologist .Nevertheless, we conducted a limited number of necropsies for aborted fetuses.ResultsIn the most cases, arthrogryposis was the most common musculoskeletal defects and at necropsy, malformations of the brain included hydranencephaly, porencephaly, hydrocephalus and cerebellar hypoplasia, mainly in the brain stem and gray and white matter of the brain and cerebellum were observed. Histopathologic lesions included chronic multifocal lymphoplasmacytic encephalitis(nonsuppurative) with extensive perivascular cuffing in some cases, formation of glial nodules mainly in the mesencephalon, thalamus, hippocampus, pons and medulla oblongata in the brain of aborted fetuses, and neuronal degeneration, necrosis and central chromatolysis mainly in the cortex and subcortical of the brain and brain stem regions of them. Furthermore, microscopic lesions are mostly linked to a neurodegenerative and necrotic cell death process in the gray matter of ventral horn of the spinal cord. Briefly, histopathologic findings in the brain and spinal cord included hyperemia, hemorrhage, non-suppurative encephalitis, mononuclear perivascular cuffing, multifocal gliosis, cavitation, central chromatolysis, neuronal degeneration and necrosis, perineuronal and perivascular edema in the all regions of the brain and acute neuronal necrosis in the gray matter of ventral horn of the spinal cord were also seen.Conclusion Our study suggested that the sheep fetuses are fully susceptible to viral infections and may even develop neurolopathological lesions upon natural infection with mentioned pathogens .Therefore ,according to ,specific lesions caused by viral infections, we believe that the histopathological pattern were detected in this study could be associated with either viral infection and or mainly by a Bunyavirus / or Flavivirus strains that extensively shares common lesions with Rift Valley fever ,Wesselsbron ,Cache valley virus / or and Akabaneviruses.Virtual SlidesThe virtual slide(s) for this article can be found here:
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    ABSTRACT: Listeria (L.) monocytogenes causes orally acquired infections and is of major importance in ruminants. Little is known about L. monocytogenes transmission between farm environment and ruminants. In order to determine potential sources of infection, we investigated the distribution of L. monocytogenes genetic subtypes in a sheep farm during a listeriosis outbreak by applying four subtyping methods (MALDI-TOF-MS, MLST, MLVA and PFGE). L. monocytogenes was isolated from a lamb with septicemia and from the brainstem of three sheep with encephalitis. Samples from the farm environment were screened for the presence of L. monocytogenes during the listeriosis outbreak, four weeks and eight months after. L. monocytogenes was found only in soil and water tank swabs during the outbreak. Four weeks later, following thorough cleaning of the barn, as well as eight months later, L. monocytogenes was absent in environmental samples. All environmental and clinical L. monocytogenes isolates were found to be the same strain. Our results show that the outbreak involving two different clinical syndromes was caused by a single L. monocytogenes strain and that soil and water tanks were potential infection sources during this outbreak. However, silage cannot be completely ruled out as the bales fed prior to the outbreak were not available for analysis. Faeces samples were negative, suggesting that sheep did not act as amplification hosts contributing to environmental contamination. In conclusion, farm management appears to be a crucial factor for the limitation of a listeriosis outbreak. Copyright © 2015 Elsevier B.V. All rights reserved.
    Veterinary Microbiology 02/2015; DOI:10.1016/j.vetmic.2015.01.025 · 2.73 Impact Factor
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    ABSTRACT: AimsListeriosis is a frequent silage-associated disease in ruminants. The slugs Arion vulgaris are invaders in gardens, vegetable crops and meadows for silage production. Field and laboratory studies were conducted to clarify whether slugs could host Listeria monocytogenes and thereby constitute a threat to animal feed safety.Methods and ResultsSelective culture of L. monocytogenes from 79 pooled slug samples (710 slugs) resulted in 43% positive, 16% with mean L. monocytogenes values of 405 CFU g−1 slug tissues. Of 62 individual slugs cultured, 11% also tested positive from surface/mucus. Multilocus sequence typing analysis of 36 isolates from different slug pools identified 20 sequence types belonging to L. monocytogenes lineages I and II. Slugs fed ≅4·0 × 105 CFUL. monocytogenes, excreted viable L. monocytogenes in faeces for up to 22 days. Excretion of L. monocytogenes decreased with time, although there were indications of a short enrichment period during the first 24 h.Conclusions Arion vulgaris may act as a vector for L. monocytogenes.Significance and Impact of the StudyHighly slug-contaminated grass silage may pose a potential threat to animal feed safety.
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