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

Theileria parva within the blood

East Coast fever is a form of theileriosis caused by Theileria parva.

Signalment

Cattle, sheep and goats can be affected.

Distribution

Mainly in tropical regions due to reliance upon tick vectors.

Clinical Signs

Theileria lifecycle

Early clinical signs include marked pyrexia, leucopaenia, inapettance, decrease in milk production, lymphadenopathy and palpably hot lymph nodes. As disease progresses, multisystemic signs develop:

Cardiovascular – Tachycardia, Petechiae and Ecchymoses, Anaemia

Respiratory - Nasal discharge, Dyspnoea, Cough

Gastrointestinal – Diarrhoea with mucus and/or blood, Inappetance, Hypomotility, Constipation

Opthalmological – Blindness, Nystagmus, Corneal oedema, Discharge, Photophobia, Increased lacrimation

Reproductive – Abortion, Stillbirths, Agalactia

Urinary – Red, brown or pink urine, Haemoglobinuria, Myoglobinuria

Dermatological – Pruritus, Plaques, Wheals, Papules, Oedema, Subcutaneous masses

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 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 and replication of T. parva is restricted within domestic cattle.

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 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. Ulcers may be seen in the peyers patches and necrosis in the lymphoid tissue. 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 are effective.

Tetracyclines are also 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.

References

Animal Health & Production Compendium, East Coast Fever datasheet, accessed 02/06/2011 @ http://www.cabi.org/ahpc/