Babesiosis - Cattle

• Cattle
  • Sudden onset
  • Often fatal if untreated
  • Causes 'pipestem' faeces
  • Clumping of red blood cells in brain capillaries can occur causing neurological signs

Epidemiology

• Determined by:
  • Number of infected ticks seeking a blood meal (tick pressure)
  • Calves under 9 months are refractory to disease
    • Can develop immunity if exposed without showing clinical signs
  • 'Premunity' (a good protective immunity) develops quickly in infected cattle causing a 'carrier state'
  • Immunity can wane in the absence of re-infection
  • Uninfected cattle remain susceptible

• Predisposing factors:
  • Susceptible animals introduced into an infected area
  • Infected ticks introduced into a clean area
  • Infected cattle introduced into an area with clean ticks
  • Temporary reduction in the tick population decreasing the transmission rate (causing enzootic instability)
  • Infected are transported or stressed in other ways, e.g. parturition

• In the UK
  • Sporadic disease
  • Enzootic instability
  • Occurs mostly during the spring and autumn during periods of greatest tick activity
  • Occurs mostly in stressed cattle under 2 years old on rough grazing
  • B. divergens the most common species
  • Ixodes ricinus is the vector
  • Trans-ovarial transmission to the next generation occurs
  • B. major occurs in South East England but is not pathogenic
    • Vector is Haemaphysalis

• Overseas
  • B. bovis causes considerable losses in cattle in many tropical and sub-tropical areas
    • In Australia an attenuated vaccine is used
    • Vector is Boophilus
  • B. bigemina causes problems in Africa and South America
    • Vector is Boophilus