Synonyms: Theileria hirci, Theileria ovis du Toit, 1918; non T. ovis Rodhain, 1916.
Disease: Malignant ovine and caprine gonderiosis, malignant ovine and caprine theileriosis.
Hosts: Sheep, goat.
Location: Lymphocytes, erythrocytes.
Geographic Distribution: North Africa, southeastern Europe, southern USSR, Asia Minor.
Morphology: The erythrocytic stages are about 80% round or oval, 18% rod-shaped and 2% anaplasma-like. The round forms are 0.6 to 2.0 u in diameter and the more elongate ones about 1.6 u long. Binary or quadruple fission takes place in the erythrocytes.
Koch bodies are common in the lymphocytes of the spleen and lymph node smears or free in these organs. They average 8 u in diameter but may range up to 10 or even 20 u. They contain 1 to 80 reddish purple granules from 1 to 2 u in diameter. Both macroschizonts and microschizonts can be found. These produce merozoites 1 to 2 u in diameter.
Life Cycle: The vector is unknown, but is possibly Rhipicephalus bursa.
Pathogenesis: This species is highly pathogenic for sheep and goats, mortalities of 46 to 100% having been reported in these animals. The disease is relatively mild in young lambs and kids in endemic areas.
The incubation period is unknown. The disease itself lasts 5 to 42 days. Acute, subacute and chronic forms have been described, the acute form being the usual one.
The disease resembles tropical bovine gonderiosis in its manifestations. There is fever following by listlessness, nasal discharge, atony of the rumen and weakness. Affected animals are anemic, and icterus is frequently present There is often a transitory hemoglobinuria. The lymph nodes are always and the liver usually swollen, the spleen is markedly enlarged, the lungs are edematous, infarcts are often present in the kidneys, and there are petechiae on the mucosa of the abomasum and irregularly disseminated red patches on the intestinal mucosa, particularly in the cecum and large intestine.
Immunity: Animals which recover from the disease are premune. There is no cross-immunity between this species and G. ovis.
Diagnosis: This depends upon identification of the parasites in stained blood, lymph node or spleen smears. In contrast with G. ovis, the erythrocytic stages are usually present in relatively large numbers, and Koch bodies are common in the lymph nodes and spleen. Inoculation of susceptible sheep or goats may also be resorted to.
Treatment: None known.
Prevention and Control: These depend upon tick control.