THEILERIA PARVA
- Synonym: East Coast Fever , Bovine theileriosis, Corridor's disease.
- Animals affected: Cattle, Water buffalo , Synceres cafer
- Highly fatal encephalitis of cattle in E.Africa known as "Turning Sickness".
Morphology
- Piroplasm form 80%- rod shaped. 1.5x0.5-1µm, round, oval comma occur.
- T. lawrenci- 65%- round or oval.
Life cycle
- Schizogony life cycle occur in reticulo endothelial system--( different from T.annulata) found in spleen, lymph node. Schizonts smaller, circular and irregular.
- Rhipicephalus. appendiculatus, R.evertsi, Hyalomma excavatum, H. dromadarii, H. truncatum- Transtadial transmission.
- PP- 4-12 days, others as previously described .
Pathogenesis
- Highly pathogenic- 90% die, mortality low in endemic area, calves- 5-50% die.
- Incubation period- 8-24 days.
- Disease runs 4-12 days.
- Acute
- Fever (107 F). Continue up to or after 7-11 days, other symptoms appear- cessation of rumination, , lachrymation, swelling of lymph node, iris, jowl,ears, tachycardia, general weakness, decrease in milk yield. diarrhoea with blood, marked emaciation, cough, icterus, breathing rapid with dyspnoea at death, oligocythemic anaemia, no haematuria.
- Sub -acute
- Similar to acute, less severe pronounced-recover but after several days.
- Mild
- Mild fever, lasting several days, lymph node swelling.
- Leisions: Similar to T.annulata
- Immunity: Recovered animals are solidly immune. Parasites clear up completely. No premunity.
- Diagnosis: Similar to T.annulata
- Treatment: No drug is effective . Same drugs indicated for T.annulata can be used.
- Control: Repeated dipping every 3 days. No cross-immunity.
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