- 2. Aquatic Animal Pathogen Containment
2.1 Risk Factors and Challenges
The Containment Standards for Facilities Handling Aquatic Animal Pathogens are needed to ensure that aquatic animal pathogens are securely contained and safely handled for experimental or commercial development purposes.
The required containment level and the stringency of operational practices are based on an evaluation of the hazards and risks posed by the aquatic animal pathogens, the proposed activities involving the pathogens, and mitigating measures. In the case of live aquatic animal holding facilities (also referred to as in vivo facilities), consideration is given to the facility's physical characteristics and also to the pathogen itself in determining the containment level required.
When aquatic animal pathogens are handled in live aquatic animal holding facilities, treatment of liquid effluent from animal holding units is a key requirement for preventing the inadvertent release of pathogens into the environment. In live aquatic animal holding facilities, water is the transport mechanism and the tanks represent the primary containment devices. Tanks must be contained to reduce the risk of spillage. Aeration should be slowed or stopped before the removal of covers to prevent the aerosolization of pathogens. In these facilities, potentially contaminated water is discharged from flow-through and recirculation-based aquatic animal holding systems. Other sources of waste water include:
- wash water discharge collected in the floor drains;
- waste water from tank and boot cleaning;
- spillage from equipment (nets, transport tanks and pails, plumbing equipment, etc.);
- regularly scheduled maintenance of animal holding units (flushing/removal of sludge from drains and pipes, debris from animal holding units, etc.);
- experimental procedures (retrieving healthy carriers, collecting moribund and dead animals, discharge of contaminated water, tissue waste from necropsies, etc.).
Contaminated or potentially contaminated liquid effluent and solid/semi-solid wastes from both laboratories and live aquatic animal holding facilities must be prevented from entering local watersheds. Exposure of susceptible aquatic species to untreated or inadequately treated liquid effluent is a hazard that must be taken seriously.
Water introduces many biological challenges that may alter the effectiveness of decontamination in live aquatic animal holding facilities. Mechanical filtration of water, also called de-bulking, is useful as a first stage of liquid effluent treatment; however, a secondary treatment such as chemical, heat, gas, ozonation, irradiation, UV or other method of treatment is also necessary to ensure effective decontamination. Given the large volumes of water involved, decontamination of waste water requires the appropriate contact time to ensure effective inactivation of infectious agents. The contact time may vary greatly depending on factors including but not limited to the level of organic loading, the method of treatment, and the resistance of the pathogens to the chosen method of decontamination. Physical and chemical factors, such as water type, suspended solids and chemical characteristics, also influence the effectiveness of any given decontamination method. Processes for sediment decontamination must also be considered and implemented.
Spread or movement of aquatic animal pathogens can also occur via fomites such as clothing, boots, hands, netting material, transport containers and equipment. In addition, the handling and management of live animals can facilitate the spread of aquatic animal pathogens. Some examples include the movement of infected animals between holding units, ineffective decontamination of multi-use equipment, maintenance of floor drains and plumbing and feeding of animals. Protocols must be developed and followed to reduce the transfer of pathogens by personnel through animal handling and/or transport, as well as to ensure appropriate decontamination of equipment and solid and liquid wastes.
It has been documented that some aquatic animal pathogens can be transmitted via the airborne route5. In laboratory situations the likelihood of aerosol generation and transmission is increased due to the processes used. This risk can be mitigated through the use of primary containment devices, such as biological safety cabinets (BSCs), and through the provision of inward directional airflow in facilities. Additional containment requirements may be required for any work that involves aquatic animal pathogens that may be transmitted via the airborne route or for pathogens that affect aquatic mammals. These projects will be assessed on a case-by-case basis by the CFIA.
5. Bishop, T. M., A. Smalls, G. A. Wooster and P. R. Bowser. 2003. Aerobiological (airborne) Dissemination of the Fish Pathogen Ichthyopthirius multifiliis and the Implications in Fish Health Management. Pages 51-61. The World Aquaculture Society.
Biosafety risk assessments must take into account the risk group (RG) of a pathogen as well as the containment level of the facility where the pathogen will be handled. Classification of pathogens according to a risk group (e.g., RG1-RG4) is an internationally accepted practice in the biosafety field and is used to categorize the relative hazard associated with a particular pathogen. The containment requirements for particular microorganisms, activities or animal species are often project-specific, necessitating the modification of containment conditions. In these instances, containment requirements will be developed or existing requirements will be adjusted based on an assessment of various hazards and risk mitigation factors, including the following:
- the current physical and operational attributes of the facilities in which the proposed work will be done;
- the geographic location of the facility;
- the proximity of actual and potential hosts or carriers of the pathogen;
- the pathogen host range;
- the existence of significant organism biotypes or strains within Canada;
- the behaviour of the pathogen in the environment;
- the virulence of the pathogen;
- the mode of transmission or spread (e.g. water-borne, direct or indirect, airborne);
- the potential for local or long-distance spread;
- the persistence of the organism in the environment (survivability in salt or fresh water, water temperature, etc.);
- the availability of pathogen risk information;
- the nature of the proposed work (in vitro, in vivo or large scale (LS) in vitro);
- the potential capacity to control or eradicate the pathogen if it is released;
- the health status of experimental animals entering the facility;
- the potential for economic or environmental impacts from the release of the pathogen;
- the biosecurity related risks (e.g., the potential for theft and misuse).
Based on a review of the above, the CFIA will determine the appropriate containment level for mitigating the risk of pathogen escape and establishment in Canada.
In the planning stages for live aquatic animal holding facilities, consideration must be given to the proximity of the facility to receiving water bodies due to the potential risk of effluent treatment failure, which could result in the release of pathogens into the environment.
Facilities handling aquatic animal pathogens must be constructed and operated to ensure the appropriate containment level for the anticipated work. Consideration is given to the pathogen itself, as well as to the procedures used to manipulate infectious materials and animals, and the volume of the biological material that will be handled.
In order to provide a framework ensuring appropriate aquatic animal pathogen containment in Canada, a containment classification system has been developed that is similar to the systems used for human, plant, and terrestrial animal pathogens. The classification system for aquatic animal pathogens consists of three levels: AQC1, AQC2 and AQC3, with associated in vitro and in vivo requirements for AQC2 and AQC3. At this time, there are no pathogens requiring AQC4; however, the decision to designate a pathogen as requiring level AQC4 will be made on a case-by-case basis.
Physical requirement descriptions are provided in Chapter 3 for AQC2 and AQC3. Operational requirement descriptions are provided in Chapter 4 for AQC1, AQC2 and AQC3. The following brief descriptions explain the major features of each containment level.
Although the physical requirements for AQC1 facilities are not formally described in this document, AQC1 corresponds to the physical and operating conditions which characterize any well-run laboratory or aquatic animal holding facility working with pathogens that may be present in the aquatic environment but that are not considered a risk to aquatic animals or to the aquatic environment. An AQC1 facility follows basic biosafety and biosecurity protocols related to personnel, animals (if present) and laboratory practices (use of laboratory coats, hand washing stations, standard biohazard waste sites and disposal, good microbiological techniques, appropriate decontamination procedures, sanitary carcass disposal, standard operating procedures (SOPs), etc.).
In AQC2 in vitro facilities, containment is achieved through facility design, operational procedures and the use of specialized equipment. An autoclave or other proven technology must be available to treat solid waste and waste water. Containment is achieved primarily through operational practices including training in biosafety and containment precautions, limiting access to authorized personnel, use of protective clothing, effective sanitation and housekeeping, and the use of good microbiological laboratory practices. All AQC1 physical and operational requirements also apply to this containment level.
For AQC2 in vivo work, certain enhancements are required in order to address the unique risks associated with the transmission of aquatic animal pathogens in water, such as the connection of drains and associated piping to an effluent treatment system.
AQC3 in vitro containment is achieved through highly specialized facilities, stringent operational procedures and the use of specialized equipment. This type of containment is achieved primarily through physical requirements including inward directional airflow and controlled access systems.
For AQC3 in vivo work, certain enhancements are required in order to address the unique risks associated with the transmission of aquatic animal pathogens in water and containment is achieved through additional physical requirements and operational practices. Washing or showering upon exit may be required based on a local risk assessment. There may be additional heating, ventilation and air conditioning (HVAC) requirements for large scale or in vivo facilities handling pathogens transmissible via the airborne route.
Enhancement of the containment standards may be required for large scale in vitro work with aquatic animal pathogens. The applicable physical and operational containment requirements depend on the specific pathogen, the volume of pathogen involved, the frequency of activities, and the processes used. Therefore, the containment requirements for handling a large volume of aquatic pathogens will be determined on a case-by-case basis. For specific requirements related to the containment and safe handling of a large volume of microorganisms for research purposes, the OBCS should be contacted. For regulatory requirements pertaining to the manufacturing and testing of vaccines or diagnostic tests for aquatic animals, the VBS should be contacted.
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