Listeriosis is an infectious disease of sheep characterized by encephalitis and sometimes abortion in pregnant ewes. It is caused by the bacteria Listeria monocytogenes, a gram-positive, motile rod that is commonly transmitted by ingesting contaminated food or water, especially silage. Clinical signs in sheep include nervous system issues like circling, head tilt, and blindness, as well as abortion and septicemia. Post-mortem examination typically shows meningitis and lesions on the brain and organs. The disease can be diagnosed by isolating and identifying the bacteria, inoculating rabbits, serology testing, or ruling out other conditions. Vaccination with a formalized bacterin can help control listeriosis in sheep flocks

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Listeriosis
(Circling disease)
Listeriosis
Def.:
• It is an acute infectious disease, characterized by encephalitis
and sotimes abortion in pregnant ewes.
Dr. Soliman Mohammed Soliman
Lecturer of Infectious Diseases

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Listeriosis
Etiology:
• Listeria monocytogenes,
• Gram positive, Motile rod, Haemolytic, Catalase positive.
Listeriosis
Mode of infection:
• Ingestion of contaminated food and water especially silage.

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Listeriosis
Symptoms: (2-6 weeks incubation period)
1. Nervous form
2. Abortion.
3. Septicemic form.
Listeriosis
Symptoms: (2-6 weeks incubation period)
1. Encephalitic phase (Nervous form):
• Fever, depression, weakness with slimy discharge from nostrils.
• One ear may droop, indicating paralysis. As well as salivation due to pharyngeal paralysis.
• Conjunctivitis with discharge from eye runs down over the face,
• Opacity of the cornea and blindness later on the course of the disease.
• Head deviated to one side and animals moves in circles always in same direction.
• The animals goes down by the end of the third day and die by the end of one week.

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A 14-month-old Holstein heifer with Listeria meningoencephalitis (“circling disease”).
Note the characteristic head tilt, ear
droop, and leaning against the wall.
The heifer circled to the right when
induced to walk, and leaned on walls
when standing.
This animal was treated and survived.

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Listeriosis
Post mortem:
• The cerebro-spinal fluid is cloudy as a results of an increased globulin and leukocyte
content.
• Congestion of the meninges with multiple necrotic focci on the brain.
• Cuffing with mononuclear cell in white matter of the cerebrum and cerebellum.
• Multiple necrotic focci in liver, spleen.

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Listeriosis
Diagnosis:
• Isolation and identification.
• Inoculation of rabbits.
• Serodiagnosis.
• The disease may be confused with enterotoxaemia, brain abscess, infectious abortions.
Control:
• Formalized whole culture bacterin of listeria monocytogenes.