East Coast Fever
Also Known As: Theileriosis — Corridor Disease — January Disease — Theileria parva — Exotic Theileriosis — Zimbabwe Theileriosis — Fortuna Disease — Murimu wa ngai (African) — Ol tegana (African)
Introduction
East Coast fever is a form of theileriosis caused by Theileria parva.
Signalment
Mainly cattle. Also possibly buffalo.
Distribution
Mainly in tropical regions due to reliance upon tick vectors.
Clinical Signs
Early clinical signs include marked pyrexia, leucopaenia, inappetence, decrease in milk production, lymphadenopathy and palpably hot lymph nodes. As disease progresses, multisystemic signs develop:
Cardiovascular – Tachycardia, Petechiae and Ecchymoses, possibly Anaemia
Respiratory - Nasal discharge, Dyspnoea, Cough
Gastrointestinal – Diarrhoea with mucus and/or blood, Inappetance, Hypomotility, Constipation
Opthalmological – Blindness, Corneal opacity, Discharge, Photophobia, Increased lacrimation
Reproductive – Abortion, Stillbirths, Agalactia
Other – Sudden death, Icterus, Marked Pyrexia, Neurological signs, Emaciation
The clinical phase usually lasts 2-3 weeks, but death occasionally occurs within a week.
Sub-lethal acute disease may be followed by complete recovery or more usually continue as chronic emaciation and decreased productivity and performance.
Corridor Disease
Acute and usually fatal form of East Coast Fever that occurs when T. parva is transmitted from African buffalo to cattle. Buffalo appear to be asymptomatic carriers.
January Disease
Also Known As – Zimbabwe theileriosis – Fortuna disease
Acute strictly seasonal fatal form of T. parva in Zimbabwe. Occurs only from December to May, or more commonly January to March, due to the distribution of its vector, Rhipicephalus appendiculatus.
Chronic signs such as emaciation and diarrhoea are rarely seen in Corridor disease and January disease due to the short disease course before death.
Diagnosis
On post-mortem examination, the lymphoid system is severely damaged and respiratory changes are marked. Froth is often present in the trachea, bronchi and bronchioles due to pneumonia and pulmonary oedema. Necrosis of the lymphoid tissue may be seen. Lymph nodes and spleen may be hyperplastic. The heart is commonly petechiated and ecchymotic. Petechiae may also be seen throughout the intestines and abomasums in ruminants.
Treatment
Buparvaquone/Parvaquone and Halofuginone chemotherapy drugs can be effective but their cost makes them often prohibitive.
Tetracyclines may also be effective against schizonts.
Immunisation with cryopreserved sporozoites is also possible but carries a risk of causing patent disease.
Control
Vaccination with cryopreserved sporozoites derived from crushed ticks is possible but expensive and not without risks.
Control of tick vectors and use of tick resistant breeds is also valuable.
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References
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This article was originally sourced from The Animal Health & Production Compendium (AHPC) published online by CABI during the OVAL Project. The datasheet was accessed on 2 June 2011. |
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