Theileriosis in sheep and goat

Introduction

• Mainly two species infect, theileria; Theileria hirci and ovis.

T. hirci (Syn. T. lestoquardi)

Introduction

• These parasite causes malignant theileriosis in sheep and goat.

Morphology

• Trophozoites are found in lymphocytes and erythrocytes as round forms, oval or rod-shaped.
• Binary or quadriple fission takes place in erythrocytes.
• Meronts (Koch bodies), measuring 8 µm in diameter in size and contain 1-80 granules. They are common lymphocytes of spleen and lymph nodes.

Life cycle

• Tick vectors are: Rhicephalus bursa and Hyalomma anatolicum anatolicum.

Pathogenesis

• Disease caused by this species resemble tropical bovine theileriosis.
• Acute form of disease is more common than sub-acute or chronic forms.
• Highly pathogenic and fatal in adult sheep and goat with mortalities of 46-100 %.

Clinical Signs

• In acute form, clinical signs observed are:

41. Fever (40-41.7 ^o C, 104-107 ⁰C)
42. Inappetance
43. Cessation of rumination
44. Rapid heart beat
45. Weakness
46. Swelling of superficial lymph nodes and eye lids.
47. Diarrhea ( Contain blood and mucus)
48. Jaundice
49. Hemorrhage in sub mucous, sub serous and sub cutaneous tissues may occur
50. Affected animals are emaciated and death occurs

• In chronic forms, there is intermittent fever, inappetence, emaciation, anemia and jaundice.

PM findings

• Lymph nodes are swollen
• Enlargement of liver, spleen and lungs become edematous
• Infarcts are present in kidneys
• Petechiae on mucosa of abdomen and irregularly disseminated red patches on intestinal mucosa.

Diagnosis

• Detection of meronts in blood smears. Lymph node biopsies.
• Based on history, clinical signs and PM findings.

Treatment/ Chemoprophylaxis

• Single injection of parvaquone @20 mg /kg body weight intramuscular or buparvaquone @2.5 mg/kg given on two occasions, are effective.
• Single dose of halofuginone @ 1.2 mg/kg orally is also affected.

Prevention and control

• Tick control measures can be considered for controlling disease.
• Topical application of acaricide may provide some level of protection, but is difficult in sheep, expensive and may have negative cost-benefit.