Louping Ill

Hosts

• Sheep
• Grouse
• Hares
• Deer elk
• Small rodents
• Ticks (eg. Ixodes ricinus)
• Man

Pathogenesis

• First phase:
  • Pyrexia with virus in macrophages
  • Recovery
• Second phase:
  • Second replication in Purkinje cells of the cerebellum and motor nuclei of the brain stem
  • Trembling, torticollis, and irregular gait
  • In grouse: starvation
  • In man: flu-like symptoms can be followed by coma, but recovery normal

Epidemiology

• Reservoir host: Ticks (Ixodes ricinus)
  • Passed to host by saliva
  • Virus can be spread between ticks when co-feeding on small rodents
• Spread mirrors seasonal tick activity

Diagnosis

• Clinical signs
• PM: virus isolation and histopathology of brain tissue

Control

• Sheep dipping in acaracides (vector control)
• Inactivated vaccines in late pregnancy can boost maternal antibody
  • Lambs inoculated >4 months of age
• Human vaccination where at risk