Susceptibility of pike Esox lucius to VHSV and IHNV and potential transmission to rainbow trout Oncorhynchus mykiss

2020 ◽  
Vol 139 ◽  
pp. 175-187
Author(s):  
J Cabon ◽  
F Almeras ◽  
M Baud ◽  
L Pallandre ◽  
T Morin ◽  
...  

Determining the origin of recurrent outbreaks of fish diseases occurring on fish farms is essential for disease prevention and control measures. In this study, we investigated the potential reservoir role of wild fish species living near salmonid farms which were regularly found to be positive for viral hemorrhagic septicemia virus (VHSV). In addition to VHSV, infectious hematopoietic necrosis virus (IHNV) was also isolated from several pike Esox lucius samples collected from a pond near the salmonid farms of interest. All isolates of VHSV and IHNV analyzed had 100% identical partial glycoprotein gene sequences. VHSV pike strain OO128-25 belonged to the Ia genotype and shared 99.1 to 99.5% nucleotide identity with strains recently isolated from the farms. IHNV pike strain OO121-8, European genotype, appeared to be different from strains from France characterized since the first isolation in 1987. Isolates representative of both viral species were highly virulent in rainbow trout Oncorhynchus mykiss. OO128-25 induced 65% mortality in pike fingerlings, whereas only weak mortality was observed with OO121-8, despite characteristic symptoms in infected fish. High levels of specific antibodies to VHSV and IHNV were detected in adult pike in the absence of clinical signs. Infection of rainbow trout in contact with experimentally VHSV- or IHNV-infected pike fingerlings indicates possible horizontal transmission. These results suggest that pike could act as a reservoir for VHSV and IHNV in the wild, providing additional evidence to explain viral persistence and resurgence in certain areas.

2020 ◽  
Vol 11 ◽  
Author(s):  
Laury Baillon ◽  
Emilie Mérour ◽  
Joëlle Cabon ◽  
Lénaïg Louboutin ◽  
Estelle Vigouroux ◽  
...  

2019 ◽  
Vol 7 (9) ◽  
pp. 302 ◽  
Author(s):  
Oh ◽  
Giri ◽  
Yun ◽  
Kim ◽  
Kim ◽  
...  

Red mark syndrome (RMS) is a fish disease caused by the infection of Rickettsial agents, especially affecting rainbow trout (Oncorhynchus mykiss). The disease is prevalent in many countries in Europe (France, Switzerland, Italy, and Slovenia), South America (Chile), North America (USA), and even Asia (Japan). However, it has not been reported in Korean aquaculture. In February 2019, rainbow trout presenting red spot lesions with swollen features on the lateral side of their body were observed at a hatchery in Korea. Fishes showing those clinical signs were fry weighing 25 ± 5 g. Moreover, the fish showing the red spot lesions were found dead, which suggests an outbreak of a mortality-causing disease. The symptoms were similar to those of RMS, and we identified the presence of Rickettsia-like organisms associated with this disease using polymerase chain reaction (PCR), sequencing, histopathologic examination, and transmission electron microscopy. The distinct features of this infection, compared to that in previous reports, were that RMS occurred in small-sized fish and accompanied mortality. Additionally, the presence of the Rickettsia agent was accompanied with outbreak of the disease. Therefore, this is the first report of RMS outbreak in rainbow trout fisheries in Korea.


2014 ◽  
Vol 25 (3) ◽  
pp. 15-19
Author(s):  
Agnieszka A. Barszcz ◽  
Ewa Siemianowska ◽  
Marcin Sidoruk ◽  
Krystyna A. Skibniewska ◽  
Józef Szarek

Abstract Poland is one of the countries with limited water resources where water saving is recommended e.g. by improving aquaculture methods to use less water. The aim of the study was to determine the influence of water quality and aquaculture technology on bioaccumulation of calcium, magnesium and sodium in muscle tissue of rainbow trout. The study was performed in spring and autumn 2011 in two trout fish farms using different farming technologies: one with flow-through system and the other with water recirculation system. The farming technology had significant influence on magnesium and sodium in waste waters but did not affect the content of the minerals in muscle tissue of rainbow trout


Animals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1043
Author(s):  
Paolo Pastorino ◽  
Ana Isabel Vela Alonso ◽  
Silvia Colussi ◽  
Giulia Cavazza ◽  
Vasco Menconi ◽  
...  

Lactococcosis is a fish disease of major concern in Mediterranean countries caused by Lactococcus garvieae. The most susceptible species is the rainbow trout (Oncorhynchus mykiss), suffering acute disease associated with elevated mortalities compared to other fish species. References reported that other salmonids are also susceptible to the disease, but no mortality outbreak has been described to date. The aim of this study was to present a mortality outbreak that occurred in brook trout (Salvelinus fontinalis) farmed in northwestern Italy during the summer of 2018. Fish exhibited clinical signs, such as exophthalmos, diffused hemorrhages localized in the ocular zone, hemorrhagic enteritis, and enlarged spleen. L. garvieae was isolated in all fish. Molecular and epidemiological characterization of the isolates, through Pulsed Field Gel Electrophoresis (PFGE), confirmed the initial hypothesis of water as vehicle of infection favoring transmission between rainbow trout farmed in upstream compartments and brook trout located in downstream tanks. Moreover, several environmental conditions affected and promoted the outbreak, among them the high-water temperature, which probably induced a physiological stress in brook trout, being way above the optimal temperature for this species, increasing the susceptibility to infection.


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