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*''L. monocytogenes'' and ''L. ivanovii'' are pathogens
*''L. monocytogenes'' and ''L. ivanovii'' are pathogens
*Carried by sheep and goats and shed in faeces and milk especially during stress
*Carried by sheep and goats and shed in faeces and milk especially during stress
*Can cause septicaemia, encephalitis and abortion
*Can cause septicaemia, encephalitis, abortion and endophthalmitis in ruminants
*Outbreaks of listeriosis often linked to silage feeding
*Outbreaks of listeriosis often linked to silage feeding
*Small Gram negative rods
*Small Gram negative rods
*Catalase positive, oxidase negative
*Catalase positive, oxidase negative
*Motile
*Tumbling motility
*Facultative anaerobes
*Facultative anaerobes
*''L. monocytogenes is haemolytic on blood agar due to a cytolytic protein, listeriolysin; grows at range of pH values and temperatures
*''L. monocytogenes is haemolytic on blood agar due to a cytolytic protein, listeriolysin; grows at range of pH values and temperatures
===Clinical infections===
===Clinical infections===
*Outbreaks of listeriosis caused by ''L. moncytogenes'' seasonal and linked to silage feeding
*Replicates in poor quality silage where the pH excedes 5.5
*Animals highly susceptible during pregnancy due to lowered cell-mediated immunity
*Neural listeriosis:
**Incubation period 14-40 days
**Dullness, circling, head tilt, facial paralysis, drool saliva, droop of eyelid and ear
**Exposure keratitis
**Fever during early stages
**Recumbency and death within a few days in sheep and goats
**Abortion up to 12 days after infection in cattle
*Septicaemic listeriosis:
**Incubation perios 2-3 days
**Lambs and occasionally pregnant sheep
**Occurs in newborn piglets, foals, poultry, adult sheep
*Keratoconjunctivitis in cattle and sheep - direct contact with silage via eye
*''L. ivanovii causes sporadic abortion in sheep and cattle
*''L. innocua'' rarely causes ovine meningoencephalitis
===Diagnosis===
*Specimens should include CSF in neural cases, cotyledons in abortion, liver, spleen and blood in septicaemia
*Immunofluorescence using monoclonal antibodies
*Histology of brain demonstrates microabscesses and lymphocytic cuffing in brainstem
*Smears of cotyledons
*High protein and cell counts in CSF
*Isolation on blood and MacConkey agar
===Treatment and control===
*Ampicillin or amoxycillin in early stages of septicaemic listeriosis
*Sub-conjuntival antibiotics and corticosteroids for ocular listeriosis
*Avoid poor quality silage and discontinue silage-feeding in an outbreak