Ehrlichia phagocytophila

Tick-borne fever

• Caused by E. phagocytophila which has now been renamed as Anaplasma phagocytophilum
• Affects ruminants in Europe
• The tick Ixodes ricinis is the main vector
• Animals remain carriers for up to 2 years, but are immune to reinfection

• Clinical signs
  • Incubation period of 2 weeks; recovery in 2 weeks
  • Fever, anorexia, reduced growth rates in young animals
  • Reduced milk production, abortion, still birth
  • Leukopenia and thrombocytopenia
  • Causes immunosuppression in young lambs causing susceptibility to tick pyaemia and louping ill

• Diagnosis
  • Intracytoplasmic morulae in neutrophils of Giemsa-stained blood smears during acute phase
  • Seroconversion detected by immunofluorescence

• Treatment and control
  • Oxtetracycline
  • Tick control
  • Prophylactic tetracyclines for lambs during first few weeks of life