Animal health: about theileriosis

Corridor disease and turning sickness are the two most common forms of theileriosis found in South Africa.

Animal health: about theileriosis
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The term ‘theileriosis’ refers to diseases caused by Theileria, which are very small parasites called protozoa. Different species of Theileria cause different diseases in animals, but the two of most concern in South Africa are corridor disease and turning sickness.

Corridor disease
Caused by Theileria parva lawrencei protozoa, corridor disease is also known as buffelsiekte, as it is spread by buffalo.
Cattle are infected when bitten by brown ear ticks (Rhipicephalus appendiculatus) that have fed on infected buffalo. The disease, which is usually fatal in cattle, occurs only in grazing areas shared by cattle and buffalo. The presence of a single buffalo for a relatively short period

may cause a serious outbreak of disease among cattle. Fortunately, cattle cannot infect one another and the disease does not continue spreading once cattle are separated from the buffalo. The disease is called ‘corridor disease’ because it was first identified in South Africa in the corridor that once lay between the Hluhluwe and Umfolozi game reserves in KwaZulu-Natal. Currently, it occurs in Limpopo, Mpumalanga and KZN.

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It is also found in Botswana, Zimbabwe, Mozambique and Angola. The disease is a major obstacle to the introduction of buffalo to cattle farming areas. After foot-and-mouth disease, it is the second-most important disease transmitted from buffalo to cattle.

Symptoms: In sick animals, the symptoms include fever, combined with depression, listlessness or standing apart, enlargement of glands (especially the one below the ear and the those in front of the shoulder and the knee), decreased milk production, loss of appetite, watery discharge from eyes, weakness and difficulty in breathing (especially just before death).

In at least 80% of infected animals, death follows three to four days after the first signs of the disease.In dead animals, the signs include fluid in the lungs, froth in the airways and enlarged glands (lymph nodes). 

Treatment/prevention: Because the disease is acute, and progresses very quickly, treatment is usually not possible. When an outbreak occurs, the cattle must be moved to an uninfected pasture and strict tick control introduced. The disease can be controlled by keeping cattle and buffalo separate from each other. By law, buffalo can only be introduced to farming areas if they test free of infection.

Turning sickness
This form of theileriosis results in brain damage. In South Africa, cattle are infected when bitten by brown ear ticks carrying Theileria taurotragi protozoa, and the disease can occur wherever the ticks are found. It usually results in death, but is not very common.

Turning sickness occurs in young cattle. Symptoms include walking in circles (giving the disease its name), blindness, staggering and paralysis. Death usually occurs within a few days of the symptoms appearing, although some animals can live for up to six months. In dead animals, you may see redness and bleeding in the brain and the covering of the brain.

Treatment/control: Treatment is usually unsuccessful. The disease can be prevented, however, by effective tick control. Ask your vet or animal health technician for help.

Source: ‘Theilerious’, compiled by the department of agriculture’s Directorate Communication Services in co-operation with ARC-Onderstepoort Veterinary