Nocardial Infection of Cultured Yellowtail
Nocardial Infection of Cultured Yellowtail
复制标题
养殖黄尾鱼的诺卡氏菌感染
DOI：
10.3147/jsfp.13.25
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发表时间：
1978
期刊：
影响因子：
0.6
通讯作者：
A. Nakagawa
中科院分区：
文献类型：
--
作者：
R. Kusuda;A. Nakagawa
自1967年以来，养殖黄尾鱼的感染危害逐年增加，迫切需要采取有效的防治措施。然而，这种感染的化疗尚未建立，部分原因是病鱼体内形成的结核使药物失效。本文简要讨论了利用该生物的生物学特性和接种疫苗的预防措施。从病原菌在海水中的生存能力和感染方式的防控措施：病原菌在海水中不能存活很长时间，特别是在露天海水中，病原菌在2天内全部被杀死。然而，在开放的海水中加入100 ppm的鱼提取物，它们存活了90多天。在利用荧光抗体法调查养殖场细菌分布时，在海水污染严重的夏季，检测到大量荧光阳性细菌。与此同时，用有毒细菌悬浮的水进行攻毒试验表明，鳃和消化系统最容易受到细菌的攻击，并且水浴中细菌水平越高，攻毒鱼的细菌数量越多。从这些结果可以推测，虽然病原菌不能在新鲜的开放海水中存活很长时间，但在污染的环境中，其生存能力大大增强。饲料中的营养物质可能参与了这种污染。这些条件将为致病菌提供一个有利的栖息地，因此，如果它们的易感性增加，就有利于感染。因此，主要的预防措施是在海水解冻期间尽量减少饲料提取物的流出，避免过度拥挤和过度喂养，从而保持养殖环境的清洁。此外，由于鱼类的伤害和营养不良是增加其易感性的最大因素，因此必须避免伤害并保持鱼类的营养良好状态。作为卫生程序，应避免意外引入带菌者和病鱼，死鱼必须焚烧，以防止疾病进一步传播。接种预防：用灭菌接种培养的黄尾虫，6周后血清抗体滴度上升到10000。此外，攻毒试验的结果也证明了疫苗接种的有效性。因此，人们认为，进一步研究疫苗接种将使预防这种感染成为可能。
Since 1967 the damage of cultured yellowtails by nocardial infection has been increasing year after year, and it is urgently required to take some effective countermeasures. However, chemotherapy for this infection has not yet been established, partly because tubercles formed in the diseased fish rendered drugs loss effective. Preventive measures by the use of biological characteristics of the organism and by vaccination are briefly discussed in this paper.1. Preventive and Control Steps from Aspects of Viability of Pathogenic Organisms in Seawater and Mode of Infection:In the seawater, the pathogenic bacteria could not survived long, especially all organisms being killed in the open seawater within 2 days. However, they survived more than 90 days by the addition of fish extracts at a level of 100 ppm to the open seawater. In the survery of bacterial distribution at culture farms by the fluorescent antibody method, a large number of fluorescent-positive bacteria were detected during the summer when the seawater was heavily polluted. Meanwhile, the challenge test with the water suspended with virulent bacteria revealed that the gill and the digestive system were most vulnerable to the bacteria, and that the higher the bacterial level in the bath, the greater the bacterial count in the challenged fish. From these results it can be assumed that, although the pathogenic bacteria cannot survive long in fresh open seawater, their viability is greatly strengthened in the polluted environment. Nutrients from the feed may participate in this pollution. These conditions would provide a favorable habitat for pathogenic bacteria, and thus, favor the infection if their susceptibility increases. The primary preventive steps will therefore be to minimize the outflow of extracts from the feed during thawing in the seawater, and to avoid overcrowding and overfeeding, thereby keeping the culturing enviromnent clean. Further, as injuries and malnutition of fishes are the greatest factors to increase their susceptibility, it will be essential to avoid injuries and to keep the fishes in nutritionally good condition. As sanitary procedures, accidental introduction of carrier and diseased fishes should be avoided, and dead fish must be incinerated for the prevention of further spread of the disease.2. Prevention with Vaccination:When cultured yellow tails were inoculated with killed bacteria, their serum antibody titers rose to 10, 000 in 6 weeks. Further, the effectiveness of vaccination was also demonstrated by the results from challenge tests. Therefore, it is considered that further studies on vaccination will make it possible to prevent this infection.