University of Khartoum

Pathogenesis and Susceptibility of Sheep to Theileria lestoquardi and Molecular Detection of other Ovine Theileri A species in the Sudan

Pathogenesis and Susceptibility of Sheep to Theileria lestoquardi and Molecular Detection of other Ovine Theileri A species in the Sudan

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Title: Pathogenesis and Susceptibility of Sheep to Theileria lestoquardi and Molecular Detection of other Ovine Theileri A species in the Sudan
Author: Hussein Elimam, Ahmed
Abstract: The objectives of the present study were to detect and identify Theileriaspecies infecting sheep in the Sudan, and to study the susceptibility of three sheep eco-types to natural T. lestoquardiinfection. Molecular survey of 219 blood samples using Reverse Line Blot (RLB) hybridization assay was conducted to detect, discriminate and identify different Theileria/Babesiaand Ehrlichiaspp. infecting sheep. In addition, three sheep eco-types – Garag (16), Watesh (15) and Desert (14) from Malignant Ovine Theileriosis ( MOT) free area were introduced into Atbara endemic area where they picked infection following natural exposure to the tick vector infestation. RLB detected three Theileriaspecies; namely,T. lestoquardi 36/219 (16.3%), T. ovis 194/219 (88.6%) andT. separata 44/219 (20%). The latter two species are reported for the first time in the Sudan. Infected sheep had variable T. lestoquardiparasitaemia (5-24%) with morbidity rate of 92.9%,43.8% and 53.3% in Desert, Garag and Watesh, respectively. Natural infection with T. lestoquardicaused obvious clinical symptoms in all sheep eco-types including pyrexia, inappetence, loss of body weight, anaemia and jaundice. Pulmonary emphysema and degenerative hepatic changes were commonly seen, together with lymphoid hyperplasia in spleen and lymph nodes. A high number of large monocytes were detected in dilated hepatic sinusoids, pulmonaryblood vessels and lymph node and splenic sinuses. Peculiar large monocytes with more than one nucleus and with dark blue inclusion-like cytoplasmic bodies were occasionally seen in the lungs. Fourdistinct abnormal features in lymphocytes (designated as Theileriamarkers), which were differentiated infected from non-infected lymphocytes were detected. These can be used in early diagnosis of T. lestoquardiinfection. The findings, also, indicated that 6 infection of erythrocytes by merozoites mainly occurred in the lungs, a new observation which may fill the gap in T. lestoquardilife cycle. Rosette phenomenon (surrounding the infected cells by 8-9 lymphocytes) and pitting phenomenon (vacuoles in schizont infected cell cytoplasm) were observed for the first time. Serum enzymes (AST, ALT and AP) were increased in all sheep eco-types. The clinical manifestations of infection, parasitological, haematological, serum biochemical findings and pathological changes were more prominent in the Desert eco-type, indicating their high susceptibility to natural T. lestoquardiinfection.
Description: 192page
URI: http://khartoumspace.uofk.edu/handle/123456789/9379
Date: 2015-04-23


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