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Listeriosis
Synonym(s): listeria monocytogenes listeriosis circling disease silage sickness
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.
Presenting signs
- Listeriosis presents as a number of different syndromes, which do not usually occur together.
- Encephalitis/meningoencephalitis: this presentation will be the focus of this article. Presenting signs include depression, walking in circles, head pressing, ear drooping, protrusion of the tongue, increased nasal secretions and increased drooling
. - Abortions Abortion and stillbirths: overview: usually late term and sporadic but can present as an abortion storm (up to 30% of a herd).
- Septicemia: Most often seen in neonates and young animals. Predominate signs include diarrhea, loss of appetite, weakness and pyrexia.
- Mastitis Mastitis: approach to the cow with acute mastitis Mastitis: approach to the cow with chronic mastitis: single or multiple quarters, chronic in nature, high somatic cell counts but often visibly ‘normal’ mammary secretion and poorly responsive to treatment.
- Keratoconjunctivitis with uveitis (“silage eye”) Bovine iritis.
Acute presentation
- Encephalitis/meningoencephalitis: depression, walking in circles, head pressing, ear drooping, protrusion of the tongue, increased nasal secretions and drooling.
Geographic incidence
- World-wide distribution.
- Less common in subtropical and tropical regions.
- Seasonal occurrence in the northern hemisphere, with the highest prevalence in the months from December to May.
- This seasonal occurrence is likely to be associated with seasonal feeding of silage.
Age predisposition
- All ages of cattle can be affected.
- Meningoencephalitis predominantly affects adult cattle.
- Septicemia is most often seen in neonatal and young animals.
Public health considerations
- Listeriosis is a zoonotic disease Listeriosis.
- Human listeriosis is considered to be rare. However, the disease can be severe and mortalities approach 50%. Human clinical syndromes include gastroenteritis, meningitis, encephalitis, abortion and stillbirths, and dermatitis.
- Zoonotic transmission can occur via ingestion of infected food products (for example, soft cheeses made with unpasteurized milk). It is also seen in veterinarians and personnel assisting cattle with dystocia, handling infected aborted fetuses and through postmortem examination of carcasses Farmer's guide to UK zoonotic diseases.
Cost considerations
- Antimicrobial therapy and supportive therapy costs.
- Labor expenses associated with treating affected stock.
- Loss of production in animals that survive.
- Loss of animals, and replacement costs for those that die.
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.