鱼绦虫病的防治措施

<正>2009年8月12日,松原某养鱼户的1000多亩(1亩≈667m2)鱼池中发生鲫鱼死亡现象,且死亡鲫鱼腹部膨大,现场剖检见腹腔中有似面条样的虫体,诊断为鲫鱼舌型绦虫病。现将此病的防治措施总结如下,供广大养鱼户参考利用。     

池塘养鱼绦虫病的防治

2009年8月12日,松原一养鱼户来电话咨询,他所养的1 000多亩鱼池中鲫鱼有死亡的,且死亡鲫鱼腹部膨大,经现场剖开腹部见腹腔中有似面条样的虫体,诊断为鲫鱼舌型绦虫病.此病的防治措施总结如下,供广大鱼类养殖户参考.     

鱼绦虫病的防治措施

<正>2009年8月12日,松原某养鱼户的1000多亩(1亩≈667m2)鱼池中发生鲫鱼死亡现象,且死亡鲫鱼腹部膨大,现场剖检见腹腔中有似面条样的虫体,诊断为鲫鱼舌型绦虫病。现将此病的防治措施总结如下,供广大养鱼户参考利用。     

日本鲺病的诊断治疗报告

2009年8月14日,西安市蓝田县一水库放养的鲢鱼、鲫鱼大批量死亡,根据发病特点、病理观察、寄生虫形态特征,确诊为由于日本鲺的大量寄生而引起的养殖鱼类死亡。经用"水虫灭一号"治疗,效果良好,用药第3天即无死鱼出现,避免了更大的经济损失。     

一起鱼出血病的诊断与治疗

1发病情况2005年7￣8月份,我镇有3家养鱼户养殖的鲤鱼、鲫鱼发生暴发性出血病。开始没有明显的症状,只是大批迅速死亡,一般药物难以控制,1星期后逐     

一例猪弓形体病的诊断报告

该猪场06年8月4日发病,开始时主人认为是感冒.随着病情的发展逐渐出现多量死亡情况,到8月10日已死亡72头,活埋56头.     

鲫鱼冲剂治疗异物性肺炎

本文所指异物性肺炎,均系兽医用胃管误将中药煎剂经气管投入肺内所致,轻者造成广泛性支气管肺炎,迁延不愈,导致患畜衰弱而致死;重者患畜多在数小时内死亡。1983年以来,笔者借鉴医学界用鲫鱼煎剂治疗肾病的经验,并受民间用鲫鱼治疗水肿等病的启迪,试用单味鲫鱼冲剂,治疗误投中     

江苏广东发生两起家禽高致病性禽流感疫情

<正>农业部新闻办公室8月12日发布,江苏省扬州市江都区、广东省清远市佛冈县发生两起家禽高致病性禽流感疫情。8月3日,扬州市江都区一养殖场饲养的鹅出现疑似禽流感症状,发病23 395只,死亡3 106只。8月4日,江苏省动物疫病预防控制中心诊断为疑似禽流感疫情。8月6日,清远市佛冈县一养殖场饲养的鸡出现疑似禽流感症状,发病1 350只,死亡1 350只。8     

猪小袋纤毛虫并发副伤寒病的诊治

1 发病情况 该户存栏经产母猪5头,50～80日龄仔猪52头,2006年8月3日上午本市某养殖户有一栏仔猪出现呈浆糊状腹泻,到下午个别猪出现水样腹泻;8月4日上午该批猪出现群体水样腹泻,并有1头死亡,畜主曾用恩诺沙星拌饲料,严重猪给注射止泻药,均未见效;到8月10日来本市门诊就诊时已死亡8头,死亡率15.4%.     

一种复合微生态制剂在鲫鱼苗养殖中的应用

鲫鱼是日常生活中一个较常见的水产品品种,近年来随着人们物质生活水平的不断提升,消费者对鲫鱼的需求量也日益增大,直接促进了鲫鱼养殖产业的发展。鲫鱼养殖水体属于一个小型的生态系统,各种微生物相互依赖,相互制约,共同维系着系统的生态平衡。但在鲫鱼养殖中后期,由于投喂量和排泄量增加,水体环境很容易出现污染现象,导致大量致病菌滋生,继而引发多种病害。而微生态制剂在解决上述养殖难题方面发挥着较明显的改善作用。笔者主要就微生态制剂在鲫鱼养殖中的应用开展试验。     

An outbreak of white spot disease (Ichthyophthirius multifiliis) in young fingerling rainbow trout (Salmo gairdneri Richardson)

An outbreak of white spot disease (‘Ich’) in fingerling rainbow trout is reported. Approximately 3,000 fish died or were killed in extremis in a period of 5 weeks. Post mortem examinations were carried out on 12 fish, all of which showed thickened whitish foci on the skin. One fish showed skin ulceration and another gill ulcerations. The gill infestation was more severe than the skin. Pathological results are described and discussed.     

Inoculation of infectious pancreatic necrosis virus serotype Sp did not cause pancreas disease in Atlantic salmon (Salmo salar L.).

Atlantic salmon were selected from a fish farm with no previous record of pancreas disease (PD) or infectious pancreatic necrosis virus (IPNV) infection. Groups of fish were inoculated with either IPNV (strain Sp) from cell culture, organ material from fish with PD or control material as phosphate-buffered saline (PBS). Virological, histological and immunohistochemical examinations were carried out throughout the experiment. None of the fish died or showed clinical symptoms of PD. Histological examination revealed no pathological changes, and immunohistochemical studies were negative. Virus was isolated only sporadically from the group inoculated with organ material, whereas it was isolated consistently from the group inoculated with virus propagated in cell culture, as well as from in-contact control fish after the first week. In a latent carrier test, changes were entirely lacking in the first mentioned group, and were only slight in the last mentioned group. The data suggest that PD is not a transmissible disease, and that IPNV isolated from a PD outbreak does not play any part in the etiology of this disease.     

Influence of Infection with Renibacterium salmoninarum on Susceptibility of Juvenile Spring Chinook Salmon to Gas Bubble Trauma

Abstract

During experiments in our laboratory to assess the progression and severity of gas bubble trauma (GBT) in juvenile spring chinook salmon Oncorhynchus tshawytscha, we had the opportunity to assess the influence of Renibacterium salmoninarum (Rs), the causative agent of bacterial kidney disease, on the susceptibility of salmon to GBT. We exposed fish with an established infection of Rs to 120% total dissolved gas (TDG) for 96 h and monitored severity of GBT signs in the fins and gills, Rs infection level in kidneys by using an enzyme-linked immunosorbent assay (ELISA), and mortality. Mortality occurred rapidly after exposure to 120% TDG, with a LT20 (time necessary to kill 20% of the population) of about 37 h, which is at a minimum about 16% earlier than other bioassays we have conducted using fish that had no apparent signs of disease. Fish that died early (from 31 to 36 h and from 49 to 52 h) had significantly higher infection levels (mean ± SE ELISA absorbance = 1.532 ± 0.108) than fish that survived for 96 h (mean ± SE ELISA absorbance = 0.828 ± 0.137). Fish that died early also had a significantly greater number of gill filaments occluded with bubbles than those that survived 96 h. Conversely, fish that survived for 96 h had a significantly higher median fin severity ranking than those that died early. Our results indicate that fish with moderate to high levels of Rs infection are more vulnerable to the effects of dissolved gas supersaturation (DGS) and die sooner than fish with lower levels of Rs infection. However, there is a substantial amount of individual variation in susceptibility to the apparent cumulative effects of DGS and Rs infection. Collectively, our findings have important implications to programs designed to monitor the prevalence and severity of GBT in juvenile salmonids in areas like the Columbia River basin, and perhaps elsewhere.     

An evaluation of the influence of stock origin and out-migration history on the disease susceptibility and survival of juvenile Chinook salmon

Various methods have been developed to mitigate the adverse effects of the Federal Columbia River Power System on juvenile Pacific salmon out-migrating through the Columbia River basin. In this study, we found that hatchery-reared spring Chinook salmon Oncorhynchus tshawytscha in the river are in varying degrees of health, which may affect delayed mortality and the assessment of the effectiveness of management actions to recover listed stocks (e.g., barging fish downstream versus leaving fish in the river). A laboratory disease challenge with Listonella anguillarum was completed on fish from Rapid River Hatchery and Dworshak National Fish Hatchery (NFH) with different out-migration histories: (1) transported by barge, (2) removed from the river before barging, or (3) left to travel in-river. Barged fish from Rapid River Hatchery experienced less mortality than fish from Dworshak NFH. No statistical differences were found between the hatcheries with fish that had in-river out-migration histories. We suggest that the stressors and low survival associated with out-migration through the hydropower system eliminated any differences that could have been present. However, 18-25% of the fish that were barged or collected before barging died in the laboratory before the disease challenge, compared with less than 2% of those that traveled in-river. Owing to disproportionate prechallenge mortality, the disease-challenged populations may have been biased; thus, they were also considered together with the prechallenge mortalities. The synthesis of prechallenge and disease-challenged mortalities and health characteristics evaluated during out-migration indicated that the benefit of barging was not consistent between the hatcheries. This finding agrees with adult survival and delayed mortality estimates for the individual hatcheries determined from adult returns. The results suggest that the health status of fish and their history before entering the hydropower system (hatchery of origin and out-migration path) are critical variables affecting the conclusions drawn from studies that evaluate mitigation strategies.     

Yersinia ruckeri septicaemia in experimentally infected carp (Cyprinus carpio L.) fingerlings.

The presence of Yersinia ruckeri, the causal agent of enteric redmouth disease (ERM) in salmonids and a few other freshwater fish, has so far been reported from a variety of sources including the intestine of healthy carp. Since there are no data on the pathogenicity of this bacterium for carp, 15 fingerlings were experimentally infected by intraperitoneal injection of about 5 x 10(5) cells. Thirteen injected fish were moribund or died within 4 days with septicaemic lesions. Two survivors were sampled on Day 28 after infection. Yersinia ruckeri was reisolated from the internal organs of all experimental fish. By histopathological examination moribund fish had generalised bacteriaemia with inflammation, degeneration and necrotic foci in kidney, liver and spleen, corresponding to findings described previously in ERM of rainbow trout. Survivors of challenge on Day 28 had a chronic disease characterised by prominent peritonitis and enteritis, exhaustion of the erythroid, granuloid and lymphoid components in haematopoietic kidney tissue as well as focal degeneration and necrosis in organs. These data indicate a high sensitivity of carp to intraperitoneal infection with a relatively low dose of Y. ruckeri.     

Application of peracetic acid for the treatment of juvenile sander (Sander lucioperca) during Ichthyophthirius multifiliis infestation

White spot disease caused by the ciliate protozoan parasite Ichthyophthirius multifiliis (I. m.), is one of the most dangerous diseases in aquaculture and ornamental fish breeding worldwide. The parasite is characterized by three developmental stages: a reproductive tomont, an infective theront and a parasitic trophont. In sander (Sander lucioperca) breeding I. m. causes serious economic losses. After banning of the traditional therapeutic agent malachite green we have to face a state of emergency for the treatment of the ichthyophthiriasis in Germany. The peracetic acid (PAA), characterized by positive therapeutical properties, might close this gap. The purpose of our investigations was the determination of the toxicity of PES to juvenile sander as well as the evaluation of the therapeutic effectiveness of the substance to combat I. m. For juvenile sander (length 3 cm) we determined a 24-h-LC50 of 1.14 (0.97; 1.3) ppm PES. In two investigations PAA was applied in daily intervals of 0.5; 1, 3, 5 and 24 h and concentrations of 0.5; 1; 1.5 and 2 ppm to treat I.-m.-infection in sander. In test I all sander (length 9 cm) died as a result of the I.-m.-infection. However, the PAA exposed fish survived longer than the PES-free controls! This might be due to a disinfection of other pathogens by PAA. In test II, the fish (length 12 cm) were less infected than fish in test I. Four of six fish died in the group exposed with 2 ppm PAA for 24 hours. The abundance of I.-m.-trophonts was determined in mucus, fin and gill tissues of all fish. Significant differences could not be observed between test I and test II because of dissimilar: 1. exposure in time and concentration, 2. age and condition of the fish and 3. homogenity of the variances. Therefore, no therapy strategy was successful while fighting the parasitic trophonts protected by the overlaying fish tissues. We speculate that a successful therapy of I. m. with PAA is, as known e.g. for malachite green, only possible while fighting the free living stages theronts and tomonts. This will be part of our subsequent investigations.     

Fatal pentastomiasis in captive African dwarf crocodile hatchlings (Osteolaemus tetraspis).

Six eggs from a captive African dwarf crocodile (Osteolaemus tetraspis) nest were artificially incubated. Two abnormal hatchlings with incomplete absorption of their yolk sacs died within 48 hr of hatching. No parasites were detected grossly or histologically in either hatchling. The remaining four apparently healthy hatchlings died without clinical signs at 3 wk of age, 1 wk after being fed live wild-caught fish and commercially raised goldfish. Necropsy revealed multiple white small wormlike organisms within the lungs, liver, and gastrointestinal tract of all four hatchlings. Histopathologic cross sections suggested that pentastomiasis was the cause of death, and whole parasites were identified as Sebekia mississippiensis. This infection was probably contracted by ingestion of live fish intermediate hosts infected with nymphal parasites. Avoiding the use of infected live fish or untreated fish products can prevent mortality of hatchling crocodilians caused by S. mississippiensis within zoological collections.     

Pathogenesis of liver lesions caused by experimental infection with Piscirickettsia salmonis in juvenile Atlantic salmon, Salmo salar L.

Piscirickettsia salmonis, the etiologic agent of salmonid rickettsial septicemia (SRS), or piscirickettsiosis, causes substantial economic losses to the salmon industry. The pathogenesis of the disease has not been fully characterized. The aim of this study is to describe the hepatic lesions associated with experimental P. salmonis infection in Atlantic salmon juveniles. Fish were maintained in fresh water and inoculated intraperitoneally (IP), orally, or on the gill surface with P. salmonis. A group of uninfected fish was kept as control. Liver samples from 5 fish in each inoculated group and 3 controls were collected weekly and processed for histological and immunohistochemical examination. Thickening of the liver capsule by inflammatory cells was a characteristic histologic feature of IP inoculated fish. Three weeks post-IP inoculation, 8 fish had died and 2 fish were sampled. Histological changes at this time consisted of vasculitis, presence of fibrin thrombi, vacuolated hepatocytes and focal areas of necrosis. Leukocytes containing intracytoplasmic basophilic microorganisms were seen within hepatic sinusoids. Vasculitis and intracytoplasmic vacuoles were prominent features in fish inoculated orally and on the gill surface. The presence of P. salmonis within hepatocellular vacuoles, endothelial cells, and leucocytes was confirmed by immunohistochemistry. The intracellular location of P. salmonis and the vascular damage seen in infected fish are characteristic of rickettsial infections. Histological lesions induced by experimental infection with P. salmonis using the oral and gill surface routes were similar to those observed in natural outbreaks of piscirickettsiosis. The tropism of P. salmonis for endothelial cells explains the vascular lesions observed in SRS, whereas hepatic lesions are due to ischemic necrosis and direct injury by intracytoplasmic organisms.     

An Evaluation of the Influence of Stock Origin and Out-migration History on the Disease Susceptibility and Survival of Juvenile Chinook Salmon

Abstract

Various methods have been developed to mitigate the adverse effects of the Federal Columbia River Power System on juvenile Pacific salmon out-migrating through the Columbia River basin. In this study, we found that hatchery-reared spring Chinook salmon Oncorhynchus tshawytscha in the river are in varying degrees of health, which may affect delayed mortality and the assessment of the effectiveness of management actions to recover listed stocks (e.g., barging fish downstream versus leaving fish in the river). A laboratory disease challenge with Listonella anguillarum was completed on fish from Rapid River Hatchery and Dworshak National Fish Hatchery (NFH) with different out-migration histories: (1) transported by barge, (2) removed from the river before barging, or (3) left to travel in-river. Barged fish from Rapid River Hatchery experienced less mortality than fish from Dworshak NFH. No statistical differences were found between the hatcheries with fish that had in-river out-migration histories. We suggest that the stressors and low survival associated with out-migration through the hydropower system eliminated any differences that could have been present. However, 18–25% of the fish that were barged or collected before barging died in the laboratory before the disease challenge, compared with less than 2% of those that traveled in-river. Owing to disproportionate prechallenge mortality, the disease-challenged populations may have been biased; thus, they were also considered together with the prechallenge mortalities. The synthesis of prechallenge and disease-challenged mortalities and health characteristics evaluated during out-migration indicated that the benefit of barging was not consistent between the hatcheries. This finding agrees with adult survival and delayed mortality estimates for the individual hatcheries determined from adult returns. The results suggest that the health status of fish and their history before entering the hydropower system (hatchery of origin and out-migration path) are critical variables affecting the conclusions drawn from studies that evaluate mitigation strategies.

Received November 18, 2009; accepted January 6, 2011