Mohammed M E, Mellor P S
AFRC Institute for Animal Health, Pirbright Laboratory, Woking, Surrey.
Epidemiol Infect. 1990 Dec;105(3):619-32. doi: 10.1017/s0950268800048263.
The seasonal incidence of bluetongue virus (BTV) in Central Sudan is related primarily to fluctuations in the prevalence of the vector, Culicoides imicola. Population densities of this midge begin to rise with the onset of precipitation and peak during October, before falling sharply at the end of the rainy season in November. These are also the months of BTV transmission. Populations of C. schultzei, the commonest midge in Central Sudan, are also related to the rainy season but this species does not seem to be involved with BTV transmission. BTV serotype 2 was isolated from C. imicola confirming the status of this midge as a known vector but a second isolate of the same serotype was made from a mixed pool of Culicoides not including C. imicola. This suggests that BTV transmission in the Sudan may involve more than one species of Culicoides. Epizootic haemorrhagic disease virus (EHDV) serotype 4 and a palyam virus were isolated from C. schultzei which indicates that this species may be involved in the transmission of BT-related viruses. Seven further virus isolates from sentinel calves at Shambat (Khartoum) confirmed the presence of BTV serotypes 1, 4 and 16, and an untyped EHDV (designated 318) in the Sudan. All of the viruses isolated and identified during the course of this work are recorded from the Sudan for the first time.
苏丹中部蓝舌病毒（BTV）的季节性发病率主要与传播媒介库蠓（Culicoides imicola）的流行率波动有关。这种蠓的种群密度随着降雨开始而上升，并在10月达到峰值，然后在11月雨季结束时急剧下降。这些月份也是BTV传播的月份。苏丹中部最常见的蠓种舒氏库蠓（C. schultzei）的种群数量也与雨季有关，但该物种似乎不参与BTV传播。从库蠓中分离出BTV血清型2，证实了这种蠓作为已知传播媒介的地位，但同一血清型的第二个分离株是从不包括库蠓的混合库蠓池中获得的。这表明苏丹的BTV传播可能涉及不止一种库蠓。从舒氏库蠓中分离出了流行性出血病病毒（EHDV）血清型4和一种帕利亚姆病毒，这表明该物种可能参与与BT相关病毒的传播。从喀土穆的尚巴特的哨兵小牛中又分离出7种病毒，证实苏丹存在BTV血清型1、4和16，以及一种未分型的EHDV（命名为318）。在这项工作过程中分离和鉴定的所有病毒都是首次在苏丹记录到的。
