Advanced Biosecurity in Aquaculture: Controlling Koi Herpesvirus (KHV) with Virokill®

A Scientific and Professional Perspective for the Aquatic Health Sector

Koi Herpesvirus Disease (KHVD), caused by Cyprinid Herpesvirus-3 (CyHV-3), represents one of the most serious biological threats to both ornamental koi and food-fish carp production worldwide. With reported mortality rates reaching 80–100% under favorable conditions, KHV outbreaks lead to severe economic losses and long-term biosecurity challenges.

As part of its commitment to sustainable veterinary and aquaculture solutions, The Arab Pesticides & Veterinary Drug Mfg. Co. (MOBEDCO) provides Virokill® as a scientifically validated disinfectant for comprehensive aquatic biosecurity.

1. Koi Herpesvirus: Epidemiology and Pathogenesis

1.1 Biological Characteristics

KHV is an enveloped double-stranded DNA virus that primarily targets:

• Gill epithelium

• Skin and mucus layers

• Renal and hematopoietic tissues

Its lipid envelope is essential for infectivity, making it vulnerable to oxidative and surfactant-based disinfectants.

1.2 Temperature Dependency

Disease expression is strongly correlated with water temperature:

• Optimal replication range: 16–25°C

• Below 13°C: latent or subclinical infection

• Above 28°C: reduced viral activity

This “thermal window” explains the seasonal peaks observed in spring and autumn.

1.3 Carrier State and Transmission

Recovered fish remain lifelong carriers and may shed virus under stress conditions such as:

• Transport

• Handling

• Overstocking

• Poor water quality

Transmission occurs through:

• Direct fish-to-fish contact

• Contaminated water

• Shared equipment (nets, tanks, transport containers)

Consequently, eradication depends primarily on preventive biosecurity and environmental disinfection.

2. Virokill®: Chemistry and Mode of Action

2.1 Active Technology

Virokill® is based on stabilized potassium peroxymonosulfate (PPMS) combined with optimized surfactant systems.

This formulation enables:

• High oxidative potential

• Effective penetration of biofilms

• Stability in organic-rich water

2.2 Mechanism of Viral Inactivation

Virokill® inactivates KHV through a multi-step process:

1. Surfactant Penetration
   Lowers surface tension, enabling access to viral particles and mucus layers.

2. Envelope Disruption
   Destabilizes the lipid bilayer of the virus.

3. Oxidative Denaturation
   Oxidizes viral proteins and nucleic acids, preventing replication.

Scientific studies confirm that PPMS-based disinfectants achieve >99.999% viral reduction even under high organic load and low-temperature conditions.

3. Advantages of Virokill® over Conventional Disinfectants

Virokill® combines high antimicrobial efficacy with operational safety, making it suitable for continuous use in aquaculture systems.

4. Application Protocols for KHV Control

Effective biosecurity depends on maintaining validated concentration–time (C×T) parameters.

4.1 Routine In-Water Sanitization (Preventive Use)

Objective: Reduce background viral and bacterial load.

• Dosage: 1 g / 1,000 L

• Frequency: Once per week

• Application: Pre-dissolve in water and distribute in high-flow areas

• Recommendation: Switch off UV/ozone for 6–12 hours

This dose maintains viral suppression without compromising nitrifying bacteria.

4.2 Enhanced Protection (High-Risk Periods & Quarantine)

Objective: Control viral shedding during stress and acclimation.

• Dosage: 2 g / 1,000 L

• Frequency: Every 3 days for 21 days

• Use cases:

  • New stock introduction

  • Show preparation

  • Seasonal temperature transition

Monitor dissolved oxygen and ammonia levels during intensive programs.

4.3 Equipment and Facility Disinfection

Objective: Prevent mechanical transmission.

• Concentration: 1% solution (10 g/L)

• Contact time: ≥10 minutes

• Applications:

  • Nets and bowls

  • Transport tanks

  • Footbaths

  • Handling tools

Rinse with clean water before reuse.

4.4 Terminal Pond Sterilization (Post-Outbreak)

Objective: Complete system reset after KHV detection.

• Dosage: 20 g / 1,000 L

• Fish status: Empty system only

• Application: Once, followed by flushing and drying

This protocol eliminates residual viral reservoirs in biofilms and sediments.

5. Integration into Aquaculture Biosecurity Systems

For maximum effectiveness, Virokill® should be embedded in Standard Operating Procedures (SOPs):

5.1 Core Biosecurity Measures

• Controlled access to facilities

• Dedicated equipment per unit

• Mandatory foot dips

• Routine water disinfection

• Quarantine of new stock

5.2 Monitoring and Documentation

• Record dosing schedules

• Track water parameters (pH, DO, NH₃, NO₂⁻)

• Maintain disinfection logs

• Verify equipment sanitation

This systematic approach ensures regulatory compliance and operational continuity.

6. Environmental and Occupational Safety

Virokill® offers a favorable safety profile:

• Degrades into oxygen and potassium salts

• No persistent residues

• Low corrosivity

• No occupational exposure limits when used correctly

This makes it compatible with modern sustainability and environmental discharge standards.

7. Strategic Value for Commercial and Ornamental Operations

By reducing pathogen pressure, Virokill® contributes to:

• Lower mortality rates

• Improved growth performance

• Faster recovery after treatments

• Reduced antibiotic dependency

• Enhanced export and certification compliance

For high-value koi collections and intensive carp production, this translates into measurable economic and reputational benefits.

Conclusion

Koi Herpesvirus remains a permanent risk in global aquaculture due to its high infectivity and lifelong carrier state. Curative treatment is not currently available; therefore, prevention and environmental control are the only reliable management strategies.

Virokill®, supported by scientific evidence and professional application protocols, provides a comprehensive solution for:

• In-water viral suppression

• Equipment sterilization

• Facility disinfection

• Long-term biosecurity management

Through its advanced oxidizing technology, operational safety, and environmental compatibility, Virokill® represents a cornerstone of modern aquatic health programs.

By integrating Virokill® into structured biosecurity systems, aquaculture professionals can effectively break the transmission cycle of KHV and safeguard the sustainability of their production and ornamental assets.

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