Macroscopic and Microscopic Findings in Theileria lestoquardi Naturally Infecting Sudanese Sheep

Malignant Ovine Theileriosis (MOT), caused by Theileria lestoquardi, is a major constraint for sheep production in many areas of the world including Sudan. Export sheep and sheep products are a major component of Sudan national economy and foreign income. Despite the importance of the disease, there is a considerable lack of detailed information regarding the postmortem and histological manifestations in the infected sheep. To specify the macroscopic and microscopic findings in sheep infected with MOT, 45 Sudanese sheep, T. lestoquardi negative were selected and were maintained for 3 months under natural ticks challenge. Necropsy was performed on 15 dead infected and 4 euthanized non-infected control, all pathological lesions were recorded. Kidneys, liver, lungs, spleen, heart, lymph nodes, stomach, intestine, pancreas and brain from test and control groups were sampled, fixed and were processed for histopathological examinations. The 15 infected sheep displayed severe enteritis with scattered areas of petechial hemorrhages on the serosal and mucosal surface along the small and large intestines. In most animals (n = 7-14), their superficial lymph nodes, liver and spleen were enlarged and their gall bladder were distended. Heart showed petechial hemorrhages and kidneys were congested. All infected animals (100%) revealed sever pneumonia associated with edema and frothy exudates. Comparatively, the most remarkable microscopic lesions in infected sheep were obviously seen in the lungs which exhibited emphysema, congestion, collapse and proliferation of large mononuclear cells. The present study indicates that T. lestoquardi infections are accompanied by severe pulmonary involvements, suggesting that emphysema and interstitial pneumonia may lead to respiratory failure and could provide evidence for death. Our findings may assist our knowledge about the microscopic and macroscopic lesions caused by T. lestoquardi and could contribute to raise awareness among veterinary authorities regarding the pathognomonic lesions for early and/or differential diagnosis.