ISSN 2398-2993      

Listeriosis

obovis

Introduction

  • Cause: Listeria monocytogenes bacteria; a small, non-spore-forming, facultative anaerobic, gram-positive rod.
  • Signs: the three classic presentations of listeriosis are:
    • Neural disease, eg meningoencepahalitis (most common clinical presentation).
    • Visceral disease - septicemia in neonates and young animals, also mastitis, endocarditis, keratoconjunctivitis and uveitis.
    • Reproductive disease - abortions and still births.
  • Additionally, atypical pneumonia caused by listeria has been documented in feedlot cattle and is thought to be caused by inhalation of bacteria.
  • Diagnosis: provisional diagnosis is based on history and clinical presentation. A definitive diagnosis can be obtained postmortem on histopathological examination of the brainstem. Culture of cerebrospinal fluid can be diagnostic, but it is difficult to isolate the organism.
  • Treatment: several possible regimes. Potassium penicillin, procaine penicillin or oxytetracycline. Other supportive treatments may include NSAIDs, fluid therapy and B vitamins.
  • Prognosis: invariably fatal if left untreated. If treatment is initiated, the prognosis depends on the interval between clinical signs and the commencement of therapy; the longer the interval the poorer the prognosis. Prognosis is poor with the presence of nystagmus, excitation and absence of a menace response.

Pathogenesis

Etiology

  • Listeria monocytogenes Listeria monocytogenes: a small, non-spore-forming, facultative anaerobic, gram-positive rod.
  • Ubiquitous in the soil and environment.
  • Optimal temperatures for the growth of the organism are between 30-37°C/86-98.6°F.
  • Optimal pH for the growth of the organism are between 4.5-9.6.
  • It is capable of surviving in feces for 16.5 months, on dry straw for 207 days and in dry soil for 2 years.

Predisposing factors

General

  • Consumption of contaminated materials. Common sources of Listeria monocytogenes include:
    • Spoiled silage at the ends of trench silos.
    • Decaying or rotting forage at the bottom of the feed bunks or haystack.
    • Poultry litter that has been used for bedding.
    • Compost piles.

Specific

  • Consumption of poorly preserved silage containing listeria monocytogenes (high pH >5.5, low dry matter and often contains soil) Feed: preservation.
  • Host risk factors include poor nutritional state, inclement weather events, stress of transportation Handling cattle: transportation, stress of pregnancy and parturition.

Pathophysiology

  • The pathogenesis of encephalitic listeriosis is not completely understood.
  • Ascending infection by Listeria monocytogenes is thought most likely. The bacteria invades a compromised mucous membrane of the oral cavity, eg through a wound or teeth eruption sites, and spreads up the trigeminal nerve to the trigeminal nucleus in the pons of the brainstem. Lesions are most severe in the pons and medulla of the brainstem, where suppurative inflammation and necrosis are seen producing neuritis, meningitis and encephalitis.
  • Although hematogenous spread has been demonstrated under experimental conditions, lesions in natural infection are most consistent with ascending infection of the trigeminal nerve.
  • The organism is capable of surviving in monocytes and macrophages.

Timecourse

  • Incubation can be as long as 2-6 weeks.
  • Disease is usually sudden onset in presentation.

Epidemiology

  • Listeriosis is usually a sporadic disease.
  • Commonly only affects one or two individuals in the herd.
  • However, outbreaks can occur (although usually affecting less than 10% of a herd).

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.
  • Boileau M & Gilliam J (2017) Brainstem and cranial nerve disorders of ruminants. Vet Clin North Am Food Anim Pract 33 (2), 67-99 PubMed.
  • Schweizer G, Ehrensperger F, Trogerson P & Braun U (2006) Clinical findings and treatment of 94 cattle presumptively diagnosed with listeriosis. Vet Rec 158 (17), 588-592 PubMed.

Other sources of information

  • Parkinson T J, Vermunt J J & Malmo J (2019) Diseases of Cattle in Australasia: A Comprehensive Textbook. New Zealand Veterinary Association Foundation for Continuing Education, USA. pp 442-445 & 665-685.
  • Cantile C & Youssef S (2016) Nervous System. In: Pathology of Domestic Animals Volume 1. 6th edn. Eds: M G Maxie, Jubb K V F, Kennedy J P & Palmer N C. Elsevier, USA. pp 362-363.
  • Radostits O M, Gay C C, Blood D C & Hinchliff K W (2006) Veterinary Medicine. In: A Textbook of the Diseases of Cattle, Sheep, Pigs, Goats and Horses. 7th edn. Saunders, China. pp 805-810.

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