Synonyms: Theileria lawrencei, Gonderia bovis.
Disease: Corridor disease, buffalo disease, malignant syncerine gonderiosis, Rhodesian malignant bovine gonderiosis.
Hosts: Cattle, African buffalo (Syncerus caffer). The buffalo is the natural host.
Location: Lymphocytes, erythrocytes.
Geographic Distribution: Union of South Africa, Southern Rhodesia.
Prevalence: This disease is widely distributed in Southern Rhodesia, both in cattle and African buffaloes. In the Union of South Africa its distribution is much more restricted, and it occurs only in cattle which have come in contact with ticks from premune African buffaloes. It takes its name from the fact that it was first found here in the Corridor, a stretch of 100 square miles of land between the Hluhluwe and Umfolozi Game Reserves where buffalo abound. It has also been found around Kruger National Park.
Morphology: The erythrocytic stages are oval, round, piriform or comma-shaped, and indistinguishable from those of G. mutans. About 55% are round or oval. There are relatively few Koch bodies in the lymphocytes of the spleen and lymph nodes or free in these organs. They average 5 u in diameter but may range up to 10 u. They contain 1 to 16 or 32 reddish purple granules 0.5 to 2 u in diameter and are practically all of the macroschizont type. The mature macromerozoites are 2.0 to 2.5 u in diameter, and the mature micromerozoites are 0.7 to 1.0 u in diameter.
Life Cycle: The vector is Rhipicephalus appendiculatus, and transmission is stage-to-stage. The parasite stages in the tick are unknown.
Pathogenesis: Corridor disease is similar to East Coast fever and tropical gonderiosis in its manifestations. G. lawrencei is highly pathogenic for cattle, the mortality being about 80%. African buffaloes, however, are highly resistant and serve as the reservoir of infection for cattle.
The incubation period following tick transmission is 12 to 20 days, with a mean of 15 days. The disease itself lasts 5 to 15 days, with a mean of 10 days. Peracute, acute, subacute and mild forms have been described. The acute form is the usual one.
There is usually no anemia, altho oligocythemia may occur. Icterus may be present, but hematuria is not. The lymph nodes, spleen and liver are often swollen, edema of the lungs is pronounced, characteristic ulcers are usually present in the abomasum, and infarcts are sometimes present in the kidneys.
Immunity: Animals which recover from infection with G. lawrencei are premune. There is no cross-immunity between this species and G. mutans, but there is partial or complete cross-immunity between it and T. parva.
Diagnosis: Same as for other species of Gonderia and Theileria.
Treatment: No effective drugs are known for the treatment of Corridor disease, but there is some evidence that chlortetracycline may suppress the disease if given repeatedly during the incubation and patent periods.
Prevention and Control: These depend upon tick control and upon prevention of association between cattle and African buffaloes.