Background Aquaculture of major freshwater fish species is the pillar industry of Tianjin's fishery economy. However, with the continuous intensification of production systems, viral diseases have occurred frequently and become a bottleneck problem constraining the healthy development of the industry.
Objective To systematically summarize the epidemic patterns, pathogen characteristics, and technological advances in prevention and control of viral diseases affecting major freshwater fish in Tianjin, this review conducted a comprehensive analysis based on regional surveillance data from 2019 to 2024 together with domestic and international research findings, aiming to provide a theoretical basis for regional disease prevention and control. Progress Surveillance data from 2019 to 2024 indicate that viral diseases in major freshwater fish in Tianjin exhibit a multi-pathogen alternating epidemic pattern. Spring viraemia of carp (SVC) showed phased fluctuations in positive detection rates, reaching a peak of 53.3% in 2019, declining to 0% during 2021–2022, rebounding to 20% in 2023, and showing zero detection in 2024. Koi herpesvirus disease (KHVD) maintained a relatively stable overall prevalence; however, the local isolate KHV-TJ1601 demonstrated extremely high virulence, causing mortality up to 93.3% in healthy koi. Grass carp hemorrhagic disease (GCHD) has shown an explosive epidemic trend since 2022, with positive detection rates rising from 80% to 100% and remaining at high levels. Carp edema virus disease (CEVD), although exhibiting low overall detection rates, produced localized outbreaks with mortality exceeding 80%. The study found that the four viruses differ significantly in taxonomic status, virion morphology, genomic characteristics, epidemic water temperature, and pathological features. Detection technologies have progressed from traditional immunological methods to polymerase chain reaction (PCR)-based techniques, and further to field rapid detection technologies including loop-mediated isothermal amplification (LAMP), recombinase polymerase amplification (RPA), and clustered regularly interspaced short palindromic repeats (CRISPR)/Cas systems. Prevention and control strategies encompass the research and development of inactivated, live-attenuated, subunit, DNA, and virus-like particle (VLP) vaccines, while bioactive components from medicinal plants and probiotic preparations also demonstrate promising antiviral potential. Conclusion/Prospect The prevention and control situation of viral diseases in major freshwater fish in Tianjin remains severe, with prominent characteristics of multi-pathogen co-occurrence. Future efforts should strengthen novel vaccine design based on multi-omics technologies and reverse vaccinology, promote the standardized application of isothermal amplification and CRISPR-based field rapid detection technologies, and construct a comprehensive prevention and control system integrating vaccination with ecological regulation to safeguard high-quality industrial development.
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