Animal Biorisk Management

1. Introduction: Scope and Context

Welcome back to this series of modules on biorisk management. In this module we will briefly cover biorisk management when working with animals. Animal biorisk management encompasses the systematic identification, assessment, mitigation, and oversight of biological risks associated with the use of animals in research, agriculture, diagnostics, and field operations.

Animals are used globally:

• As models for human disease research
• In the study of animal pathogens
• In food production systems
• In national and agricultural biosecurity programs

Because of this, animal facilities represent complex risk environments involving:

• Occupational safety
• Zoonotic disease transmission
• Environmental protection
• Economic security
• Public health

Animal biosafety shares foundational principles with laboratory biosafety. However, it introduces additional variables including:

• Animal behavior and unpredictability
• Species-specific pathogen shedding
• Aerosol and allergen generation
• Arthropod and parasite vectors
• Environmental dissemination risks

Effective animal biorisk management requires an integrated and multidisciplinary approach incorporating veterinary medicine, biosafety science, environmental engineering, and biosecurity practices.

2. Foundational Concepts: Hazard and Risk

Let’s review some foundational concepts from laboratory biosafety.

A hazard is a biological, physical, chemical, or environmental source with the inherent potential to cause harm.

A risk is the probability that harm will occur under defined conditions, combined with the severity of the resulting consequences.

In animal facilities, hazards commonly include:

• Infectious agents
• Animal-inflicted injuries
• Allergens and aerosols
• Sharps and surgical instruments
• Arthropod vectors
• Environmental contamination

Risk assessment requires structured evaluation of:

1. The agent or hazard
2. The procedures being performed
3. The facility design and engineering systems
4. The experience and training of personnel
5. Potential consequences for animals, humans, and the environment

Risk is not static. It varies according to species, pathogen characteristics, stress conditions, and operational variables.

3. The One Health Framework

Animal health, human health, and environmental health are interdependent. Many pathogens cross species barriers, creating shared risk domains.

For example:

• Foot-and-mouth disease represents a severe agricultural and economic threat.
• Lyme disease illustrates wildlife-to-human vector transmission.
• Bubonic plague persists in wildlife reservoirs globally ready to infect people.

Even when work appears confined to animal research, its implications may extend to public health and national biosecurity.

4. Major Categories of Risk in Animal Facilities

Let us now review the primary categories of risk encountered in animal facilities.

4.1 Physical Injury Hazards

Animal handling introduces mechanical injury risks not typically present in laboratory-only environments.

Potential injuries include:

• Bites and scratches
• Crushing injuries
• Goring or trampling
• Pinching or striking

Risk severity increases with:

• Animal size
• Stress level
• Behavioral temperament
• Handler inexperience

Control measures include:

• Species-specific training
• Physical restraint systems
• Chemical sedation under veterinary supervision
• Appropriate PPE (e.g., bite-resistant gloves, steel-toed footwear)

Competence in animal handling is itself a biosafety control.

4.2 Zoonotic and Reverse Zoonotic Disease

Zoonoses are diseases transmitted from animals to humans.
Reverse zoonoses (anthroponoses) occur when humans transmit pathogens to animals.

Representative zoonotic agents include:

• Salmonella Typhi
• Macacine alphaherpesvirus 1
• Histoplasma capsulatum
• Toxoplasma gondii
• Coxiella burnetii

Transmission routes include:

• Respiratory aerosols
• Mucous membrane contact
• Percutaneous injury
• Gastrointestinal ingestion

Animal facilities often involve asymptomatic carriers. Therefore, absence of clinical signs does not equate to absence of risk.

Risk mitigation requires interruption of the chain of infection:

• Reservoir
• Portal of exit
• Mode of transmission
• Portal of entry
• Susceptible host

Engineering controls, PPE, vaccination programs, and surveillance testing serve to disrupt this chain.

4.3 Aerosols and Allergens

Animals produce substantial biological particulates including:

• Dander
• Urinary proteins
• Bedding dust
• Manure particles

Over time, these exposures may lead to occupational allergy, hypersensitivity or asthma.

One important engineering control used in small animal facilities is the cage change station.

These systems use downward airflow to pull allergens and aerosols away from the worker’s breathing zone to reduce worker exposure during cage manipulation.

Respiratory protection, including powered air-purifying respirators (PAPRs), may be required in higher-risk environments.

Engineering controls at the source are more reliable than reliance on PPE alone.

4.4 Sharps and Necropsy Hazards

Animal procedures and necropsies generate significant sharps hazards.

Examples include:

• Needles and syringes
• Scalpel blades
• Surgical instruments
• Bone fragments
• Animal teeth and claws

Control measures include:

• Elimination or minimization of sharps use
• Immediate disposal in approved containers
• No recapping of needles
• Proper restraint of animals
• Cut- and puncture-resistant gloves

Necropsy procedures should be treated as controlled contamination events due to potential aerosol and fluid release.

4.5 Vectors and Parasites

Animals, particularly wild-caught specimens, may carry vectors such as:

• Ticks
• Fleas
• Lice
• Mosquitoes

Some associated vector-borne diseases include:

• Western and Venezuelan equine encephalitis
• Plaque
• Lyme disease
• Rocky Mountain spotted fever

and many more

Vector control programs and facility screening are essential components of risk mitigation.

4.6 Environmental Release of Pathogens

Another risk of working with animals is the potential for pathogen escape. This may occur through:

• Animal escape
• Aerosol exhaust systems
• Untreated wastewater
• Carcass disposal
• Contaminated equipment or fomites

Environmental release may result in infection of other animals, wildlife, or human populations. Agricultural pathogens, in particular, can produce substantial economic impact.

Secondary containment and facility engineering design are critical safeguards.

5. Animal Biosafety Levels (ABSL)

Animal biosafety levels, similar to laboratory biosafety levels, integrate:

• Work practices
• Safety equipment and
• Facility design

ABSL1 is for work with well-characterized, low-risk agents.
ABSL2 is for work with moderate-risk agents; enhanced primary containment.
ABSL3 is for work with indigenous or exotic agents with aerosol transmission potential.
ABSL4 is for work with high-risk, life-threatening agents requiring maximum containment.

The foundational level, Animal Biosafety Level One (ABSL1), is designed for low-risk work and includes specific architectural requirements. Facilities at this level should be isolated from high-traffic areas to prevent unauthorized access to animal rooms, which should utilize key or card access controls. Doors must be equipped with self-closing and self-locking mechanisms, remain closed, and open inward. It is also essential to include a handwashing sink at the exit near the door, and air recirculation should be avoided. Instead, all air drawn into the room must be expelled, as animal odors necessitate this measure. The graphic illustrates a simplified design, highlighting the door, sink, and animal housing system.

The next level of biocontainment for animal research is classified as Animal Biosafety Level 2 (ABSL2), which is designated for higher-risk activities. An area designated for changing clothing should be available, allowing personnel to change and put on the appropriate personal protective equipment (PPE). Animals housed under ABSL2 conditions are typically maintained in enhanced primary containment, which may consist of individually ventilated cages (IVC) arranged on racks. IVCs provide HEPA-filtered supply and exhaust air, confining aerosols and allergens at the cage level. Ideally, an autoclave should be located nearby to facilitate immediate decontamination of bedding, animals, and any infectious waste generated within the animal room. This increased containment capacity is essential when engaging in higher-risk work.

For activities categorized as higher risk, various enhancements can be integrated into facilities to further increase personal and environmental protections. These modifications should be determined based on a thorough risk assessment and implemented as necessary. Possible enhancements include improved ventilation controls to eliminate the potential release of infectious aerosols from the room. This may involve the installation of HEPA filters on exhaust systems, accompanied by interlocked supply and exhaust fans to prevent positive pressurization within the room. Additionally, personal exit showers may be mandated to ensure that personnel decontaminate their entire bodies before exiting the area. Further PPE requirements may also be necessary for those working with non-contained animals, particularly as larger animals present challenges to primary containment.

Visual representations of these enhancements can be found in the accompanying slide. The left image depicts a decontamination shower designed for use following animal room work; the middle image illustrates card swipe access, a component of enhanced biosecurity protocols; and the right image features a simple layout of a small animal holding room. The design includes an entrance, an anteroom with sink and shower facilities, and an animal room situated at the core. A pass-through autoclave is positioned at the rear of the room for the sterilization of all waste, allowing for immediate removal from the facility. Within the animal room, a biosafety cabinet is present, and animals are housed in individually ventilated cages on racks as a means of primary containment.

It is important to note that certain animals are not suitable for housing within primary containment systems. The humorous illustration of a cow within a biosafety cabinet exemplifies this limitation. While the objective is to maintain animals within primary containment whenever feasible, there are instances where the dimensions required to accommodate large animals exceed the capabilities of conventional containment systems. Consequently, unique challenges arise in managing highly communicable infectious diseases within animals that cannot be placed in primary containment.

The United States Department of Agriculture (USDA) has established a specialized level of containment known as Animal Biosafety Level 3 (ABSL3-Ag) specifically for agricultural applications. This level features a unique building design that incorporates numerous characteristics of animal biosafety level 4, including personal change rooms equipped with showers, airlocks for personnel and equipment, double-door autoclaves, and a single-pass directional pressure gradient air system complete with air filtration for both supply and exhaust. Additionally, the facility must include electrical interlocks to prevent the positive pressurization of the spaces. The design also requires a central effluent liquid decontamination system and sealed interior surfaces, effectively creating an airtight environment that minimizes the risk of leakage from the room. Furthermore, rigorous certification and validation processes for the room and its supporting systems are essential. It is important to note that constructing and maintaining such facilities can be both costly and complex.

There are numerous references in the literature and online for those seeking additional information. Notably, the Canadian authorities have developed a comprehensive handbook of containment standards for veterinary facilities. In the United States, the “Biosafety in Microbiology and Biomedical Laboratories” (BMBL) document, developed by the Centers for Disease Control and Prevention (CDC) and the National Institutes of Health (NIH), also offers valuable insights into animal biocontainment. Additionally, a specialized group has published a veterinary containment facilities handbook, which may serve as another helpful resource. Furthermore, it is essential to consult the Agricultural Research Service facilities and design standards 242.1, which outlines the construction standards applicable to various animal biocontainment levels from an engineering perspective. I encourage you to consult these references for further information regarding animal biocontainment.

7. Administrative and Biosecurity Controls

Effective animal biorisk management requires robust administrative infrastructure. A good administrative program requires:

• Comprehensive biosafety manual
• Species-specific standard operating procedures
• Institutional Biosafety Committee (IBC) oversight
• Institutional Animal Care and Use Committee (IACUC) oversight
• Registration and inventory tracking
• Medical surveillance programs
• Emergency response planning

Inventory management must account for:

• Animal numbers
• Infectious status
• Pathogens present
• Personnel access logs
• Waste destruction documentation

Documentation is fundamental to biosecurity integrity.

8. Hierarchy of Controls in Animal Biorisk Management

Risk mitigation follows the established hierarchy:

1. Elimination – Avoid use of animals or high-risk agents where feasible.
2. Substitution – Use less virulent organisms or alternative models.
3. Engineering Controls – Containment caging, ventilation systems.
4. Administrative Controls – SOPs, training, oversight.
5. Personal Protective Equipment – Final barrier to exposure.

Animal systems require layered controls due to variability in behavior, shedding, environmental interaction, and vector presence.

9. Conclusion

Animal biorisk management is a structured, multidisciplinary process integrating:

• Veterinary science
• Biosafety principles
• Occupational health
• Environmental engineering
• Biosecurity

While traditional risk group classifications provide useful frameworks, they do not fully capture the complexities of animal systems. Species-specific behavior, environmental shedding, vector ecology, and agricultural consequences must all be considered.

Effective programs rely on the following:

• Comprehensive risk assessment
• Layered mitigation strategies
• Engineered containment systems
• Administrative oversight
• Ongoing surveillance and documentation

Through systematic application of these principles, animal facilities can protect:

• Personnel
• Animal populations
• The environment
• The broader community

As a summary, watch the video, which outlines procedures followed at animal biosafety level one, as well as the risk control measures that should be implemented.

Thank you for watching this module on animal biosafety. Please take the quiz designed to reinforce key elements covered in this training.