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Louping Ill

Louping Ill






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    Louping Ill Louping Ill Presentation Transcript

    • ~Also called infectious encophalomyelitis of sheep ~occurs in Scottland,England, Ireland, Czechoslovakia, and Soviet Union ~it similar to spring-summer encephalitis, which afflicts man
    • Name~ from peculiar leaping gait of ataxic animals ~inocuble by intracerebral injection Sheep ~ primarily infected (cattle, swine, dog, horses can be affected also)
    • Clinical Signs ~ nervous signs and died of severe meningocephalomyelitis ~ isolation of the virus is through the brain Antibodies ~ found in wild red deer (tangential host)
    • Character of the disease 6-18 days ~incubation time in sheep Signs ~ dullness and high temperature (107 o F or more) -virus present in the blood
    • Character of the disease ~improvement is temporary and nervous system may involved Nervous signs ~ muscular incoordination, tremors, cerebellar ataxia, and paralysis
    • Character of the disease Acute cases ~ death occurs Chronic cases ~ paralysis Human poliomyelitis ~ disease resembles and begins as a generalized infection
    • Character of the disease Acute cases ~ death occurs Chronic cases ~ paralysis Human poliomyelitis ~ disease resembles and begins as a generalized infection
    • Character of the disease Virus isolation ~ brain, cervical spinal cord ~ serum samples from horses contain hemagglutinating, complement-fixing, precipitating, and neutralizing antibodies
    • Character of the disease Microscopic lesions ~ typical viral encephalomyelitis and meningitis ~can have degeneration of neurons (Pukinje cells) ~no typical gross lesions
    • Character of the disease Intracerebral inoculation of brain virus ~ produce in sheep, cattle, swine, mice, hamster, and monkeys Rabbits and guinea pig – resistant Monkeys and mice – can be readily infected by instilling the virus in their nostrils
    • Character of the disease Deer = had viremia and produce antibodies Horses = susceptible to the disease and have viremia (cause:nymphs of castor bean tick Ixodes ricinus )
    • Properties of the virus ~has properties of a flavivirus with infectious RNA (spherical) Hemagluttination-inhibition test ~ crossing occurs with other flavivirus Freezing and glycerol – agent is preserved
    • Properties of the virus Saline and broth ~ the virus deteriorates (dilute and acid suspensions) Complement fixation test ~ antibodies are transient; limited value in diagnosis
    • Cultivation Minced chick medium, cultures of pig kidney, and embryonated eggs = used in obtaining artificial culture
    • Epizootiology Monkeys and humans ~ Contract infection by inhaling infective droplets Sheep ~ bloodsucking arthropods (transmission) Principal transmitter~ Ixodes ricinus
    • Epizootiology Larval tick ~ feeding on sheep Early summer ~ prevalent period Midsummer ~ subsides Early fall ~ reappears *based on tick activity
    • Epizootiology Maintenance of the disease ~ based on sheep (amplifier host)
    • Immunity Natural / artificial injection ~ results in solid, enduring immunity Vaccine consists of formalinized nerve tissue ~ effective protection for young lambs
    • Diagnosis Clinical signs ~ difficult to distinguish ~inoculating and intracerebrally with nerve tissue serological test ~ to make a definitive diagnosis
      • Prevention and Control
      • By immunizing all newborn lambs of nerve tissue vaccines shortly after weaning
      • Remove all castor bean ticks in flocks
      • 3. Injecting of vaccines
    • Prevention and Control Toxoplasma gondii ~ infection in sheep will suppress immunizing effect of a single injection of virus vaccine
    • Disease in Human ~ occurred in 3 laboratory workers ~ illness was influenzal in nature ~ Virus was not recovered in patients, but neutralizing agents appeared in their serums
    • Disease in Human ~ Shepherds in infected flocks can be affected ~ the disease is diphasic (febrile illness of short duration) ~ become delirious and was comatose
    • Disease in Human ~virus was isolated by inoculation of mice (intracerebrally and intramuscularly) with cerbrospinal fluid ~ neutralizing antibodies appears on the blood.
    • Disease in Human ~ recovered almost but with mild symptoms of ataxia