3. ETIOLOGY
Theileriosis is caused by theileria spp. eg., Theileria parva, Theileria annulata, Theileria
ovis.
In cattle, goats, sheep and wild and captive ungulates.
Theileriosis is a hemoparasitic disease caused by protozoa of the genus theileria.
Theileria species affect domestic and wild ruminants, especially in Africa, Europe,
Australia, and Asia.
The parasites are transmitted by tick.
These parasites, undergo repeated merogony in the lymphocytes ultimately releasing
small merozoites, which invade the red cells to become piroplasms.
Theileriosis, have a variety of tick vectors which cause infections ranged from clinically
inapparent to rapidly fatal.
4. BOVINE THEILERIOSIS
Bovine theileriosis is caused T. parva. The tick vector is Rhipicephalus
appendiculatus. in East Africa.
East coast fever generally occur in cattle but also buffalo and occurs
ECF is prevalent throughout the water area.
T. parva is a highly fatal disease in cattle and this disease is a great
threat on the development of the livestock industry, with losses of about
10,000 cattle per year in Zambia.
8. PATHOGENESIS
Transmitted through bite of ticks of genus Hyalomma.
Transmitted mechanically by inoculation of blood and tissue
suspension made from spleen, lymph nodes and liver of infected
animals.
After entry the organism at sporozoit stage remains in blood
circulation and enters in erythrocytes but they don’t multiply.
Multiplication occurs in lymphocytes where it forms schizonts .
9. Multiplication occurs in lymphocytes where it forms schizonts .
Infected lymphocytes are ruptured and schizonts are released and
other lymphocytes are affected.
Later some schizonts are differentiated unto merozoites .
Rapidly multiplying schizonts are causing severe damage to
lymphoid cells through their lysis.
10. CLINICAL FINDING
High rise of temperature (104F-106F)
Enlargment of regional superficial lymph node.
Increse heart and respiratory rate.
Tense eye balls along with watery lacrimation.
Labourrd respiration, serous nasal discharge and coughing.
Depression and petechial haemorrhages on counjuctiva.
Anemia
Bilirubinuria and jaundice in some case.
Occasional nervous signs.
11. DIAGNOSIS
Demonstration of protozoan parasite in
blood smear
lymph node biopsy
Symptoms and lesions
Immunodiagnostic tests for demonstration of antigen /antibody
ELISA
12. TREATMENT
Buparvaquone is the most effective drug and the recommended dose
in cattle, sheep and goat is 2.5mg /kg BW.
Broad spectrum antibiotics like tetracycline, oxytetracycline,
chlortetracycline have been used with success.
Halofuginone lactate @ 1.2 mg/kg b.wt orally about recovery
Bereline has been used with success.
14. SANITARY PROPHYLAXIS
Bovine theileriosis is generally controlled by the use of acaricides to kill
ticks, but this method is not sustainable.
Acaricides are expensive, they cause environmental damage, and over
time ticks develop resistance to them requiring newer acaricides to be
developed.
More sustainable and reliable methods for the control of theileriosis that
deploy a combination of strategic tick control and vaccination are
desirable, however, these are yet to be successfully applied on a large
scale in endemic areas.
Sanitation and disinfection measures are not generally effective in
preventing transmission of theileriosis.
15. MEDICAL PROPHYLAXIS
Chemotherapeutic agents such as buparvaquone are available to treat
T. parva and T. annulata infections.
Treatments with these agents do not completely eradicate theilerial
infections and lead to the development of carrier states in their hosts.
Recovery from one strain of T. annulata confers cross-protection against
most other strains.
Complete cross-protection does not occur with T. parva Inactivated
vaccines.
16. None are available Live attenuated vaccines.
Reliable vaccines of known efficacy have been developed for T. parva
and T. annulata.
For T. annulata, the vaccine is prepared from schizont-infected cell lines
that have been isolated from cattle and attenuated during in-vitro culture.
The vaccine must remain frozen until shortly before administration