Babesia

Babesia Life Cycle Diagram - Dennis Jacobs & Mark Fox RVC

Babesia Life Cycle - Mariana Ruiz Villarreal

• Infects a wide range of host species in different areas of the world

• Babesiosis has severe effects on cattle production in parts of the world
  • Prevents European breeds from being successful in tropical regions where ticks are endemic.
  • Occurs sporadically in the UK and Ireland causing losses of around £8 million per year

Life Cycle

• Both trans-stadial and trans-ovarian transmission occurs

• Each female tick produces 3000 eggs

• The tick is the definitive host

• Babesia multiplies in the red blood cells by budding
  • Forms 2-4 daughter cells (species dependent)
  • Giemsa blood smears can differentiate between species using 'Difquik' stain

• Babesia species are either small or large depending on the size of the daughter cells

• Small Babesia
  • E.g. B. divergens
  • E.g. B. gibsoni
  • Peripheral nucleus
  • Obtuse angle

• Large Babesia
  • E.g. B. major
  • E.g. B. canis-complex
  • Central nucleus
  • Acute angle

• Daughter cells disrupt the red blood cell and are released
  • Spread and infect other red blood cells

• Antigen is released which adsorbs onto other red blood cells
  • Causes haemolysis and haemoglobin pigmentation
  • Causes haemolytic anaemia, haemoglobinuria and fever

Enzootic Instability

• Low rate of transmission

• Few infected ticks

• Infrequent exposure

• Immunity wanes or is completely absent in many individuals

• Low levels of herd immunity

• Higher incidence of disease

Enzootic Stability

• High rate of transmission

• Many infected ticks

• Frequent exposure boosts immunity

• High level of herd immunity

• Lower incidence of disease

Cattle Babesiosis

• Dogs
  • Complex epidemiology
  • Recognised species are extending their endemic ranges due to the discovery of the small Babesia species, pet passport scheme and increased overseas travel
  • Large species comprises 3 subspecies
    • B. canis canis is the most important
      • Dermacentor vector
      • Largely confined to southern Europe but is spreading
    • B. canis uses Rhipicephalus as a vector and is spreading northwards through Europe
    • B. gibsoni is now established in the USA and South-East Asia
  • British dogs have no immunity as no species are endemic to the UK so are highly susceptible if taken abroad
  • Prevention of tick bites by use of an 'Amitraz' collar is currently the best method of protection

• Horses
  • 2 species occur
  • B. equi is the most pathogenic
  • Not endemic to the UK
  • Serology using ELISA or IFAT to diagnose

• Sheep and goats
  • Several species
  • Little clinical significance