First detection of infectious spleen and kidney necrosis virus (ISKNV) associated with massive mortalities in farmed tilapia in Africa

Ramírez‐Paredes, José Gustavo; Paley, Richard; Hunt, William C.; Feist, Stephen W.; Stone, David M.; Field, Terence R.; Haydon, David J.; Ziddah, Peter A.; Nkansa, Mary; Guilder, James; Gray, Joseph V.; Duodu, Samuel; Pecku, Emanuel K; Awuni, Joseph A.; Wallis, Timothy S.; Verner–Jeffreys, David W.

doi:10.1111/tbed.13825

Cited by 63 publications

(50 citation statements)

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“…All sampled animals were positive for ISKNV as observed through PCR and sequencing techniques. The histopathological and electron microscopic findings were similar to those described in other studies (Subramaniam et al, 2016; Ramírez-Paredez et al, 2020). The presence of megalocytic cells in many tissues and the visualization of viral particles in the spleen confirm ISKNV as one of the etiological agents of this fatal outbreak.…”

Section: Discussionsupporting

confidence: 89%

“…E. tarda, S. agalactiae, and A. hydrophila were the key bacteria isolated from diseased fish. Natural co-infection of bacterial pathogens and ISKNV in diseased Nile tilapia has already been described in other studies (Dong et al, 2015; Ramírez-Paredez et al, 2020) and it seems to be a common feature of this viral infection. The impact of these co-infections on the severity of the outbreak as well as the possible control measures to be adopted need to be addressed.…”

Section: Discussionsupporting

confidence: 66%

“…In this study, ISKNV was detected in diseased Nile tilapia from a Brazilian farm. In previous ISKNV outbreaks in fish, the viral pathogen was associated with massive mortalities in the fry and juvenile stages (Subramaniam et al, 2016; Ramírez-Paredez et al, 2020). This was also observed in our investigation.…”

Section: Discussionmentioning

confidence: 99%

“…In both reports, outbreaks were observed in tilapia fry and juveniles, with clinical manifestations of lethargy, gill pallor, and ascites, and a mortality rate of about 75%. Recently, a mass mortality associated with ISKNV infection was described in Ghana, in cage culture systems of Nile tilapia in Lake Volta (Ramírez-Paredez et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

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First report of Infectious Spleen and Kidney Necrosis Virus in Nile tilapia in Brazil

Figueiredo

Tavares

Dorella

et al. 2020

Preprint

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SummaryIn June 2020, an atypical fatal outbreak in the Nile tilapia farm was investigated. Twenty-three animals were collected and different tissues were used for bacterial isolation, histopathological and electron microscopic examination, and viral detection using molecular methods. A large number of megalocytes were observed in the histopathological analysis of several tissues. Icosahedral virions, with a diameter of approximately 160 nm, were visualized inside the megalocytes through transmission electron microscopy of the spleen tissue. The virions were confirmed to be infectious spleen and kidney necrosis virus (ISKNV) through PCR and sequencing analyses of the fish samples. This viral pathogen is fatal in the early stages of Nile tilapia farms in the USA, Thailand, and Ghana; however, until now, there have been no reports from Brazil. In 14 of the sampled fish, Streptococcus agalactiae, Edwardsiella tarda, or Aeromonas hydrophila infections were also detected. This is the first report of fatal ISKNV infections in the Brazilian Nile tilapia fish farms.

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Section: Discussionsupporting

confidence: 89%

Section: Discussionsupporting

confidence: 66%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

First report of Infectious Spleen and Kidney Necrosis Virus in Nile tilapia in Brazil

Figueiredo

Tavares

Dorella

et al. 2020

Preprint

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“…Since red seabream iridovirus (RSIV) was firstly documented in cultured red seabream in Shikoku Island, Japan, in 1990 [ 25 ], and the genus Megalocytivirus was defined in 2005 [ 26 ]; in the past 30 years, megalocytivirus has become a worldwide threat to extensive farmed freshwater and marine bony fish distribution in Asia, Europe, America, Africa, and Australia [ 3 , 5 , 27 , 28 ]. The traditional megalocytiviruses were composed of three classic clades, namely RSIV, ISKNV, and TRBIV, and a further six subclades of RSIV-I and RSIV-II, ISKNV-I and ISKNV-II, and TRBIV-I and TRBIV-II.…”

Section: Discussionmentioning

confidence: 99%

Scale Drop Disease Virus Associated Yellowfin Seabream (Acanthopagrus latus) Ascites Diseases, Zhuhai, Guangdong, Southern China: The First Description

Li²,

et al. 2021

Viruses

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Scale drop disease virus (SDDV), an emerging piscine iridovirus prevalent in farmed Asian seabass Lates calcarifer in Southeast Asia, was firstly scientifically descripted in Singapore in 2015. Here, an SDDV isolate ZH-06/20 was isolated by inoculating filtered ascites from diseased juvenile yellowfin seabream into MFF-1 cell. Advanced cytopathic effects were observed 6 days post-inoculation. A transmission electron microscopy examination confirmed that numerous virion particles, about 140 nm in diameter, were observed in infected MFF-1 cell. ZH-06/20 was further purified and both whole genome and virion proteome were determined. The results showed that ZH-06/20 was composed of 131,122 bp with 135 putative viral proteins and 113 of them were further detected by virion proteome. Western blot analysis showed that no (or weak) cross-reaction was observed among several major viral proteins between ZH-06/20 and ISKNV-like megalocytivirus. An artificial challenge showed that ZH-06/20 could cause 100% death to juvenile yellowfin seabream. A typical sign was characterized by severe ascites, but not scale drop, which was considerably different from SDD syndrome in Asian seabass. Collectively, SDDV was confirmed, for the first time, as the causative agent of ascites diseases in farmed yellowfin seabream. Our study offers useful information to better understanding SDDV-associated diseases in farmed fish.

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Isolation and Characterization of Aeromonas jandaei from Nile Tilapia in Lake Volta, Ghana, and Its Response to Antibiotics and Herbal Extracts

et al. 2022

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Production of Nile Tilapia Oreochromis niloticus contributes to economic growth in many countries. However, there has been a decline in its production over the years due to the influx of bacterial infections, with Aeromonas jandaei as an emerging threat. In this study, we identified and characterized A. jandaei from cage‐cultured Nile Tilapia in Akosombo Stratum II of Lake Volta in Ghana and evaluated its response to commonly used antibiotics using the disc diffusion and agar well diffusion methods for herbal extracts at various concentrations (10, 30, 50, 70, and 100 mg/mL). The herbs considered included guava Psidium guajava leaf, bitter leaf Vernonia amygdalina, neem Azadirachta indica leaf, and their cocktail (GBNL in the ratio of 1:1:1). The bacterium was isolated from swab samples from the head kidneys of 27 moribund Nile Tilapia collected from nine fish farms. Samples were screened for A. jandaei by culturing and identification using morphological and molecular techniques. The bacterium isolate from fish in the study, identified as A. jandaei GH‐AS II, had 92–93% identity to A. jandaei reference strains. Infection of healthy Nile Tilapia (n = 210) with the bacterium isolate showed that 1.0 × 105 CFU/mL was the lethal dose causing 50% mortality. Antibiotic susceptibility testing showed that A. jandaei GH‐AS II was resistant to tetracycline and ampicillin. Herbal extracts at the various concentrations inhibited the growth of the bacterium isolate, with a significant increment in the zones of inhibition with increasing concentrations of leaf extracts. However, GBNL showed prominence compared to the other extracts only at 100 mg/mL. Management of A. jandaei GH‐AS II by using herbal extracts at Nile Tilapia farms in Lake Volta may be recommended since the use of antibiotics, such as tetracycline and ampicillin, may not yield the needed result.

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First detection of infectious spleen and kidney necrosis virus (ISKNV) associated with massive mortalities in farmed tilapia in Africa

Abstract: This is an open access article under the terms of the Creat ive Commo ns Attri bution-NonCo mmercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

Cited by 63 publications

References 31 publications

First report of Infectious Spleen and Kidney Necrosis Virus in Nile tilapia in Brazil

First report of Infectious Spleen and Kidney Necrosis Virus in Nile tilapia in Brazil

Scale Drop Disease Virus Associated Yellowfin Seabream (Acanthopagrus latus) Ascites Diseases, Zhuhai, Guangdong, Southern China: The First Description

Isolation and Characterization of Aeromonas jandaei from Nile Tilapia in Lake Volta, Ghana, and Its Response to Antibiotics and Herbal Extracts

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