An outbreak of listerial myelitis in sheep

Listeria monocytogenes at the interface between ruminants and humans: A comparative pathology and pathogenesis review

The bacterium Listeria monocytogenes (Lm) is widely distributed in the environment as a saprophyte, but may turn into a lethal intracellular pathogen upon ingestion. Invasive infections occur in numerous species worldwide, but most commonly in humans and farmed ruminants, and manifest as distinct forms. Of those, neuroinfection is remarkably threatening due to its high mortality. Lm is widely studied not only as a pathogen but also as an essential model for intracellular infections and host-pathogen interactions. Many aspects of its ecology and pathogenesis, however, remain unclear and are rarely addressed in its natural hosts. This review highlights the heterogeneity and adaptability of Lm by summarizing its association with the environment, farm animals, and disease. It also provides current knowledge on key features of the pathology and (molecular) pathogenesis of various listeriosis forms in naturally susceptible species with a special focus on ruminants and on the neuroinvasive form of the disease. Moreover, knowledge gaps on pathomechanisms of listerial infections and relevant unexplored topics in Lm pathogenesis research are highlighted.

SAC C VS disease surveillance, June 2017

Shortened limbs in pedigree Aberdeen Angus calvesSpinal listeriosis in a suckled calfTickborne fever in lambsAeromonas hydrophila pleuropneumonia in finishing pigsThese are among matters discussed in the disease surveillance report for June 2017 from SAC Consulting: Veterinary Services (SAC C VS).

Brainstem and Cranial Nerve Disorders of Ruminants

Asymmetrical signs of brainstem disease occur relatively infrequently in ruminants. The most common differential diagnoses include listeriosis, otitis media/interna, and pituitary abscess syndrome. Although these conditions produce signs of brainstem dysfunction, the diseases can usually be differentiated based on historical findings and subtle clinical differences. Basic laboratory diagnostic tests are often not specific in the definitive diagnosis but may be supportive. Advanced imaging techniques have proven to be useful in the diagnosis of otitis media/interna. Presumptive clinical diagnosis is confirmed at necropsy. Treatment involves a prolonged course of antibiotic therapy but is unrewarding in cases of pituitary abscess syndrome.

Rhombencephalitis Caused by Listeria monocytogenes in Humans and Ruminants: A Zoonosis on the Rise?

Listeriosis is an emerging zoonotic infection of humans and ruminants worldwide caused by Listeria monocytogenes (LM). In both host species, CNS disease accounts for the high mortality associated with listeriosis and includes rhombencephalitis, whose neuropathology is strikingly similar in humans and ruminants. This review discusses the current knowledge about listeric encephalitis, and involved host and bacterial factors. There is an urgent need to study the molecular mechanisms of neuropathogenesis, which are poorly understood. Such studies will provide a basis for the development of new therapeutic strategies that aim to prevent LM from invading the brain and spread within the CNS.

Brainstem and cranial nerve abnormalities: listeriosis, otitis media/interna, and pituitary abscess syndrome

This article reviews three disorders associated with multiple asymmetric cranial nerve deficits in ruminants: encephalitic listeriosis,otitis media/interna, and pituitary abscess syndrome. Emphasis is placed on encephalitic listeriosis, an infectious disease of the brainstem and cranial nerves caused by Listeria monocytogenes. The epidemiology, pathophysiology, clinical manifestations, diagnosis,and treatment of encephalitic listeriosis are reviewed, and differences between cattle and small ruminants are noted. Physical and neurologic examination findings that distinguish otitis media/interna and pituitary abscess syndrome from encephalitic listeriosis are highlighted.

A review of Listeria monocytogenes and listeriosis

Following the initial isolation and description in 1926 Listeria monocytogenes has been shown to be of world-wide prevalence and is associated with serious disease in a wide variety of animals, including man. Our knowledge of this bacterial pathogen and the various forms of listeriosis that it causes has until recently been extremely limited, but recent advances in taxonomy, isolation methods, bacterial typing, molecular biology and cell biology have extended our knowledge. It is an exquisitely adaptable environmental bacterium capable of existing both as an animal pathogen and plant saprophyte with a powerful array of regulated virulence factors. Most cases of listeriosis arise from the ingestion of contaminated food and in the UK the disease is particularly common in ruminants fed on silage. Although a number of forms of listeriosis are easily recognized, such as encephalitis, abortion and septicaemia, the epidemiological aspects and pathogenesis of infection in ruminants remain poorly understood. The invasion of peripheral nerve cells and rapid entry into the brain is postulated as a unique characteristic of its virulence, but relevant and practical disease models are still required to investigate this phenomenon. This review offers an up to date introduction to the organism with a description of virulence determinants, typing systems and a detailed account of listeriosis in animals. Experimental and field papers are reviewed and further sections deal with the diagnosis, treatment and control of listeriosis in animals. A final part gives an overview of listeriosis in man.

Spinal manifestation of neurolisteriosis

Spinal symptoms in acute bacterial meningitis are rare. In a series of 10 cases of neurolisteriosis, we observed 2 spinal complications, one due to an acute intramedullary abscess, the other caused by chronic spinal arachnoiditis. Therefore, if spinal symptoms develop in acute bacterial meningitis, Listeria monocytogenes infection should be considered and early adequate antibiotic treatment be implemented.