【摘要】 通过流行病学的调查,病理学和病原学的研究,确定发生于北京鸭小鸭的“背脖病”是鸭病毒性肝炎(Duck virus Hepatitis—简称DVH)。总结了综合诊断本病的几项要点。结合生产实践,采用“抗DVH血清”和“免疫蛋黄”被动免疫小鸭和强毒主动免疫母鸭等措施,初步总结出对爆发DVH鸭场采取紧急防治的措施,应用于北京市9个鸭场,基本上能控制住本病的流行。更多还原

【Abstract】 In July, 1972, an outbreak ot an inlectious disease, commonly known as “neck-bending” disease occurred in a farm in Peking. The present paper reports briefly the results of our studies of this disease and its prevention.It was found that the course, the symptoms and the lesions of this disease resembled those of Duck virus hepatitis (DVH), first reported and described by Le-vine and Fabricant in the U. S. (1950). A strain of virus was then isolated from the affected duckling, but the serum neutralization test with Duck hepatitis antiserum from tlu- united states has not been able to carry out. Electron microscopy of thin section made on the diseased liver of affected ducklings also revealed virus-like particles in a degenerated liver cell. The shape and size of these particles coincided closely with those of the viral strain observed and measured by Reuss(1959), and Richter et al. (1964). The disease was prevented and controlled by immunization of ducklings and breeders in the outbreak farms.The diagnosis of this diesease as DVH were based on the following criteria.1. In an outbreak, only ducklings of 5-12 days old were susceptible, juvenile and adult ducks were unaffected.2. The disease ran a rapid, violent course, with most of the loses on the second and third days of the outbreak. The survivors recovered rapidly. The mortality varied considerably in different farms or even in different hatches of the same farm with a wide range of 10-90%, usually 20-60%. 3. The infected ducklings at first failed to keep up with the brood, very soon, they stoped moving and squatted down with eyes partially closed. After no more than one day, they collapsed and lied on their sides or breast, kicking spasmodically with both legs and died within about 1-5 hours with their heads bending backward-to their backs, hence the name “neck-bending disease” was used.4. The most conspicuous lesions detected at necropsy were in the liver. Macro-eo-pically the liver was usually enlarged and buttle in texture, its colour uoually changed from normal to yellowish brown. On its surface there were usually manv punctate or ecchymotic hemorrhages. Microscopically, the prominent liver lesions were formed by infiltration of chronic inflammatory cells, proliferation of bile duet “pi-thelium and subsequent hemorrhages and extensive necrosis of hepatic cells.The final diagnosis of this disease would be, however, rearing and isolating virus from chicken or duck embryo.General treatments in the infected farm to prevent the spreading of DVII under field conditions are:1. Proper management is important. Strict isolation of the diseased duckling- may be useful in reducing the spreading. However, for practical purposes, imisunjza-tion treatments seemed to be more effective.2. Immunization of ducklings. When the first deaths in an outbreak of the discae occnred, duck antiserum of the recovery infected ducks or egg-yolk preparation from hyperimmunized ducks was injected subcutaneously into all ducklings ot the brood and the subsequent hatches. One treatment usually sufiiced to protect the duckiing-from the disease.3. Immunization of breeders. The most practical means we thus far used in con-trolling and preventing DVII was vaccination of breeding stock. For a high level of passive immunity in the offspring, two successive doses of crude liver suspenaions sterilized with penicillin and streptomycin administered to parent stock at two weeks apart were required. Two weeks after the second vaccination, the hyperi immnnized breeding duck gave rise to a progeny with an effective passive DVH protection. The protection period or immunity lasted at least one year. If this method is uaed,theegg yolk from the hyperimmunized ducks may be used instead ot the immune serumIt has been proved practically to have the same protective activity as immune serum,but it is more readily available and cheaper.更多还原