1993─1994年对虾暴发病的流行病学研究

EPIDEMIOLOGICAL STUDIES ON THE EXPLOSIVE EPIDEMIC DISEASE OF PRAWN IN 1993-1994

研究了山东省１９９３─１９９４年对虾暴发性流行病的群体病症及其发展，分析了该病的地区、时间、种间分布及个体差异。结果表明：典型的虾池发病历时一周，死亡率达９０％以上；凡虾池密集（＞７０公顷／公里海岸线）、放苗量大（４５—６０万／公顷）、投入高（４５，０００—７５，０００元／公顷）的地区发病早、损失大。发病时间主要在６—７月。１９９３年病程短而急，形成一个发病高峰，近似流行病学的偏态分布（对数常态分布）；１９９４年病程长而缓，部分地区形成两个高峰。根据流行病学原理推算了１９９３年青岛流亭对虾暴发性流行病的平均潜伏期（６．０２天）和暴露日期。依据１０７个样品的切片分析，证实对虾暴发性流行病的病原为皮下及造血组织坏死病毒（Ｈｙｐｏｄｅｒｍａｌａｎｄｈｅｍａｔｏｐｏｉｅｔｉｃｎｅｃｒｏｓｉｓｂａｃｕｌｏｖｉｒｕｓ，ＨＨＮＢＶ）。还讨论了流行病发生与环境因子，如温度、溶氧、ｐＨ、浮游生物、放苗密度以及投饵等之间的关系。

The explosive epidemic disease of prawn (EEDS) in Shandong Province in 1993-1994 was studied. The course lasted about 7-10 days from the appearance of early symptoms to death and the mortality was above 90%. The distributions of EEDS on area, time and species were analysed. The area with crowded prawn ponds (>70 ha/km of sea coast line), high density larvae stocking (450,000 - 600,000 post-larvae/ha ), and big investing (45, 000 - 75,000 yuan/ha) met earlier epidemic disease explosion and suffered greater loss. The EEDS mainly occurred in June to July. The disease course in 1993 was comparatively short but violent and had one distribute peak which was similar to the logarithmic normal distribution in epidemiology. In 1994 it was longer and moderate and in some area had two peaks. The average incubation period (6. 02 days) and exposed date of EEDS in Qingdao Luting 1993 were calculated according to the epidemiologicalfundamentals. The observation of 107 sample slices confirmed that the pathogen of 1993-1994 EEDS was hypodermal and hematopoietic necrosis baculovirus (HHNBV). The relationship between disease and environmental factors such as temperature, dissolve oxygen, pH, plankton, density of prawn larvae, and feeding was discussed in this paper.