10/09/2025
Theileriosis is a tick-borne disease of livestock, particularly cattle, buffalo, sheep, and goats, caused by protozoan parasites of the genus Theileria.
Cause
Causative agent: Theileria annulata (causes tropical theileriosis in cattle), Theileria parva (causes East Coast fever), and other species.
Vector: Transmitted by ticks, mainly of the Hyalomma genus (for T. annulata).
Transmission
Occurs when an infected tick feeds on an animal and injects sporozoites.
Can also spread through blood transfusions from infected animals.
Clinical Signs
1. Acute form:
High fever (up to 41°C / 106°F)
Swollen lymph nodes (especially prescapular & parotid)
Anemia & jaundice
Loss of appetite & weight loss
Nasal discharge, lacrimation
Labored breathing
2. Chronic form:
Weakness, poor body condition
Intermittent fever
Decreased milk production
Pathogenesis
Sporozoites invade white blood cells (lymphocytes/monocytes), multiply as schizonts, then invade red blood cells as piroplasms, causing destruction of cells and immune suppression.
Diagnosis
Blood smear: Detection of piroplasms in RBCs (Giemsa stain)
Lymph node biopsy smear: Schizonts in lymphocytes
PCR for confirmation
Clinical signs + tick history
Treatment
Specific drugs:
Buparvaquone (2.5 mg/kg IM, repeat in 48–72 hrs)
Oxytetracycline (for secondary infections)
Supportive therapy:
Anti-inflammatory drugs
Blood transfusion (in severe anemia)
Fluid therapy & good nutrition
Prevention & Control
Tick control (acaricides, pour-on, spraying)
Vaccination in endemic areas (live attenuated T. annulata vaccine)
Avoiding movement of animals from endemic to non-endemic areas without precaution
