C611
- LISTERIOSIS
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Nature of the disease
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Listeriosis is an opportunistic bacterial disease caused by Listeria monocytogenes. It
affects a large range of animal species and is a severe zoonosis.
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Classification
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OIE, List C disease
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Susceptible species
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Many species are susceptible: bovines, ovines, caprine, equines, porcine, rabbits,
birds, humans.
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Distribution
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Listeriosis is worldwide distributed. In the Pacific Region it is known to
occur in Australia and in New Zeeland, it has never been reported from Guam and
Vanuatu, elsewhere the disease is poorly documented.
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Clinical signs
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In adult bovines and ovines the listeriosis often appears as an
encephalitis. Signs include:
- Fever, anorexia
- Conjunctivitis,
- Opisthotonos, Paralysis,
- Facial paralysis, flaccid lip and lowered eye lip, salivation,
- Involuntary movements, circling movements
- Coma,
Recovery rate is about 50 % in cattle and 30% in small ruminants.
In pregnant animals late abortion is common, sometimes
mastitis. Septicaemia may occur in young animals. The disease
is often unapparent in pigs and horses. In birds the disease affects
young animals and causes septicaemia and encephalitis.
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Post-mortem findings
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- Encephalitis: congestion of meninges
- Septicaemia: small necrotic foci in many organs, very numerous on
liver, haemorrhagic gastroenteritis
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Differential diagnosis
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Specimens required for diagnosis
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Isolation of L. monocytogenes can be done from brain,
cerebrospinal fluid and aborted foetuses.
Serological tests are available but are of low interest as many
animals exhibit high titres.
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Transmission |
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Listeriosis is shed in intestines of reservoir hosts and is transmitted by
contaminated food, water and between animals via the faecal-oral route.
It is commonly associated with spoiled silage and it can survive for
months in the soil. Transplacental transmission is possible.
Listeriosis in humans is usually a food borne disease.
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Risk of introduction |
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As Listeria monocytogenes is an usual host of the intestine of
ruminants it is difficult to prevent the risk of introduction of the
organism through the importation of live animals. However protection of
human from being contaminated by imported animal products should be
considered.
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Control / vaccines
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Vaccination is possible but it is no economically interesting because of
the character sporadic of the disease.
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| References
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Listeriosis In Merck Veterinary Manual, National
Publishing Inc. Eight ed, 1998, Philadelphia, p. 479-481
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McLAUCHLIN J, VAN DER
MEE-MARQUET N, Listeriosis In Zoonoses, ed by SR
PALMER, Lord SOULSEY and D.I.H. SIMPSON, Oxford University Press, Bath Press,
Avon, 1998, p.127-140
- Office International des Epizooties, 2002
- Office Vétérinaire
Fédéral Suisse
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