Equis ISSN 2398-2977

Listeriosis

Contributor(s): Linda Lou Blythe, Graham Munroe

Introduction

  • A very rare cause of meningoencephalomyelitis and keratitis.
  • Cause: infection withListeria monocytogenes.
  • Clinical signs: meningoencephalomyelitis ("nervous system dysfunction" is better for a clinical sign), abortion, pneumonia, septicemia.
  • Diagnosis: blood culture ofL. monocytogenesin septicemia cases. History of eating silage is suggestive.
  • Treatment: antimicrobials following culture and sensitivity testing. Better to start on broad spectrum antibiotics, eg amikacin, amoxicillin with clavulanate, penicillin and others, right away. All but ceftiofur and lincomycin for whichListeria monocytogeneshas been shown to be resistant.
  • Prognosis: good with early antimicrobial treatment; may be rapidly fatal in cases of septicemia or in foals.

Pathogenesis

Etiology

  • Infection withL. monocytogenes, a Gram-positive rod.
  • Primarily feed-borne, especially silage.
  • Mainly a disease of ruminants, but sporadically seen in horses.

Predisposing factors

General

Pathophysiology

  • In one case ingestion of improperly treated corn silage was linked with the disease.
  • In one survey >68% of normal horses had antibodies toL. monocytogenes.
  • The neurological form of listeriosis has signs primarily relating to brainstem and cauda equina involvement   Polyneuritis equi  .
  • The pathogenesis of encephalitic listeriosis is controversial: it appears that the micro-organism can enter nerve endings through abrasions in the buccal mucosa, lips, nostril, conjunctiva or teeth and then migrate centripetally to cause a central nervous system infection.
  • An alternative route of encephalitic infection might be hematogenous.

Timecourse

  • Septicemia may rapidly ensue following infection, especially in foals, and lead to sudden death. The incubation period can be as short as 1 day.
  • The incubation period for the encephalitic form is usually 2-3 weeks; and the course of the disease is short: 1-4 days.

Epidemiology

  • L. monocytogenescan infect other domestic animals and humans.
  • Asymptomatic carrier states have been identified.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Rutten M, Lehner A, Pospischil A & Sydler T (2006)Cerebral listeriosis in an adult Freiberger gelding. J Comp Path134, 249-253PubMed.
  • Evans K, Smith M, McDonough P & Wiedmann (2004)Eye infections due toListeria monocytogenesin three cows and one horse.  J Vet Diagn Invest16, 464-469PubMed.
  • Gudmundsdottir K B, Svansson V, Aalbaek B, Gunnarsson E & Sigurdarson S (2004)Listeria monocytogenesin horses in Iceland.Vet Rec155(15), 456-459PubMed.
  • Jose-Cunnilleras E & Hinchcliff K W (2001)Listeria monocytogenessepticemia in foals. Equine Vet J33(5), 519-522PubMed.  
  • Wilkins P A, Marsh P S, Acland H & Del Piero F (2000)Listeria monocytogenessepticemia in a Throroughbred foal. J Vet Diagn Invest12, 173-176PubMed.
  • Wallace S S & Hathcock T L (1995)Listeria monocytogenessepticaemia in a foal.  JAVMA207(10), 1325-1326PubMed.

Other sources of information

  • Hahn C H, Mayhew I G & Mackay R J (1999)Nervous System: diseases of Multiple or Unknown Sites.In:Equine Medicine & Surgery. Eds: Colahan P T, Mayhew I G, Merritt A M & Moore J N. Mosby Inc, Missouri. pp 893. ISBN: 0 8151 1743 4.


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