Theileria

Theileria parva Life Cycle Diagram - Dennis Jacobs & Mark Fox RVC

File:Lymph node smear East Coast Fever.jpg

Lymph node smear of a cow with East Coast Fever - Drs. Elizabeth Howerth and Bruce LeRoy, Department of Pathology, UGA College of Veterinary Medicine

File:H and E stain brain East Coast Fever.jpg

H and E stain of brain and meningal vessels of a cow with East Coast Fever - Drs. Elizabeth Howerth and Bruce LeRoy, Department of Pathology, UGA College of Veterinary Medicine

Theileria cervi (deer) - Drs. Elizabeth Howerth and Bruce LeRoy, Department of Pathology, UGA College of Veterinary Medicine

• Main species of veterinary importance is Theileria parva
  • Causes East Coast Fever
    • Severe, proliferative lymphatic disease of cattle
    • Central and Eastern Africa
    • Transmitted by Rhipicephalus appendiculatus
    • Trans-stadial transmission

• Other Theileria species cause production losses in cattle and sheep in the Middle East, Mediterranean and in Northern Africa

Life Cycle

• Incubation phase lasts 1 week

• Lymphoblast proliferation
  • Local lymph node first infected then spreads through body
  • Occurs in week two

• Lymphoid depletion
  • Lymphocytes killed
  • Decreases lymphopoiesis
  • Occurs in week 3

• Total incubation period takes about 18 days

Diagnosis

• Clinical signs
  • Pyrexia
  • Enlarged local lymph node
    • Usually parotid lymph node as Rhipicephalus appendiculatus feeds in the ear
  • Loss of condition

• Examine Giemsa stained smears of:
  • Local lymph node aspirated for schizonts
  • Blood smears for piroplasms in red blood cells

• Post-mortem
  • Pulmonary oedema
  • Gut mucosal haemorrhages
  • Lymph node and splenic cellular atrophy

Control

• Integrated control of both the tick vector and disease
  • Vaccination and Ectoparasiticides

• Current vaccination is live unattentuated
  • Contains frozen stabilate of ground up tick gut containing infective sporozoites
  • Long lasting oxytetracycline administered at the same time to slow down schizogony giving the immune response time to develop