Infectious diseases can spread rapidly in a herd or flock. Once a disease is suspected or identified, immediate steps must be taken to contain it:
- Isolate the animal showing clinical signs of disease.
- Implement movement restrictions until the situation is evaluated: restrict movement of all animals until exposed animals can be identified and a perimeter is established.
- Contact your veterinarian. They will help you decide what the next steps should be.
- Your veterinarian will determine if the state veterinarian should be contacted based on the size of the outbreak or type of disease in the herd or flock, such as a reportable or foreign animal disease.
- Inventory other animals in the herd, identify and isolate potentially exposed animals, and immediately implement health monitoring- take temperature twice daily and observe for clinical signs.
- Communicate with employees, service providers, visitors and other parties if involved about your biosecurity measures to contain the disease spread.
Questions to Consider Before a Disease Outbreak
Reacting to a disease outbreak is financially and emotionally expensive. The safest and most cost effective method of herd protection is to prevent disease. Each farm operator should consult with animal health professionals such as a veterinarian or local Extension Service to carefully evaluate management practices, identify specific high‐risk activities that could present potential problems, and adopt practices to prevent and mitigate those risks.
Planning ahead for a livestock disease outbreak will help you to anticipate issues/barriers that will arise such as:
How well are you equipped to handle large-scale mortality (more than 25 percent of your livestock) on your farm?
If more than 25 percent of your animals were to suddenly die, how would this impact your operation?
How prepared are you to deal with carcass disposal?
How will you get feed to your livestock?
How will you manage if restrictions on animal movement are put in place?
What resources will you need to have available, or will be able to acquire during an emergency such as a disease outbreak?
How will family and employees be affected by movement restrictions?
Prepare your farm for a quick response by posting an emergency contact list, having individual identification for your animals, and knowing what to expect in case of a foreign animal disease emergency or an infectious disease outbreak.
Create a biosecurity plan to help you anticipate how to manage one or many sick animals. Planning for a disaster will not only protect your livestock, but also your family, employees, neighboring farms and their livestock as well.
Response for Larger Livestock Disease Outbreaks
Response to livestock disease outbreak is determined by several factors. One of these factors is the type of disease causing an outbreak: reportable or a foreign animal disease.
If a quarantine is established for a farm with a livestock disease outbreak, state and local officials will define zones to determine the extent of movement restrictions and surveillance that will occur. This depends on the proximity to the index case (or the first animal or group of animals identified with the disease).
The two main types of zones surrounding the index case are the exposed/infected zone and the surveillance zone. These zones may be adjusted daily. Zones may be expanded or other zones may be established if new exposed premises are identified.
The following factors will be taken into account when the exposed zone and the surveillance zone are defined:
- Characteristics of the disease-causing agent or pathogen.
- Epidemiology of the disease incident.
- Livestock species involved.
- Environmental factors.
- Wildlife involvement.
- Natural vs. artificial barriers/boundaries.
- Geopolitical boundaries.
- Industries involved.
- Livestock movement patterns.
- Processing options (livestock and products).
The image below is an example of demarcated zones that would be established if an outbreak of highly pathogenic avian influenza (HPAI) occurred on a farm. HPAI is considered a high consequence foreign animal disease (FAD). Click on the image to download a PDF that explains the zones and activities within the zones.
Exposed or Infected Zone
The exposed zone (sometimes also called the infected zone) is defined as any area in which infection of animals has been presumed or confirmed. All premises within this area with susceptible animals and potentially contaminated materials are strictly quarantined and subject to constant surveillance.
The actual size of the zone in any one direction is determined by epidemiological factors such as terrain, the pattern of livestock movements, livestock concentrations, the weather and prevailing winds, the distribution and movements of susceptible wildlife, the estimated time elapsed since initial outbreak of disease, and known characteristics of the agent. This zone can extend several miles from the original infected farm.
The typical protocol for establishment and maintenance of exposed zones by the official agency in charge is:
1. Conduct epidemiological investigation to:
- Identify trace-ins and trace-outs. In other words, tracing the contacts infected animals had with other animals.
- Identify the source of infection.
- Determine extent of disease spread.
- Determine the time elapsed since initial outbreak of the disease.
2. Implement quarantine restrictions. Such quarantines should apply to all susceptible species and all conveyances or equipment that may have direct or indirect contact with susceptible species.
3. Establish biosecurity and movement control checkpoints on avenues of transportation into and out of the exposed zone. At this point, producers will be asked to begin enforcing biosecurity measures that are more stringent than their routine practices.
4. Restrict movement of all animals, humans, and vehicles departing the exposed zone by enforcing the following:
- Passage permitted only through biosecure travel corridors, through established biosecurity perimeters and movement control checkpoints.
- No animals or animal products can leave the zone.
- Vehicles, equipment and people may leave if strict biosecurity procedures are followed:
- Information concerning whereabouts and animal contacts is provided.
- All vehicles, equipment, and people are clean and disinfected.
- Personnel shower out.
- Human-to-animal contact policies are established and regulated, appropriate for the specific agent.
- Official permitting and permission is provided.
Local or regional hazmat teams may assist with decontamination as they have the equipment and expertise to decontaminate equipment and portable showers for personnel.
The surveillance zone is defined as the area surrounding an exposed zone in which movement of all susceptible animals and potentially contaminated materials are restricted and subject to aggressive surveillance.
This surveillance zone will surround the exposed zone. The exact boundaries of the zones will be established to optimize containment of the outbreak. In the early stages of the outbreak, all movement would likely be stopped. Once the extent of the outbreak is understood, susceptible livestock may be allowed to move within the surveillance zone with permits but not out of the zone. Non-susceptible livestock or poultry may be allowed to move within and outside of the surveillance zone with a permit.
The typical protocol for establishment and maintenance of surveillance zones by the official agency in charge is as follows:
- Ensure that all personnel working in the zone have access to appropriate and adequate personal protective equipment (PPE).
- Conduct activities to find infected animals and conduct trace backs.
- Increase awareness among all animal health professionals.
- Conduct surveillance at concentration points and epidemiologically suspect areas.
- Limit movement of non-susceptible livestock, poultry, commerce and products out of the zone to biosecure corridors and require appropriate biosecurity such as cleaning and disinfection of vehicles.
- Restrict public access to animals and wildlife.
- Implement quarantine of any suspected cases.
Implementing a Quarantine
Important activities official agencies may consider when implementing a quarantine:
- Eliminate human and animal traffic onto the quarantined farm except for essential personnel and dedicated service technicians. These individuals should not visit other farms for a minimum of 48 hours.
- Report all animal illness, deaths, and escapes.
- Prohibit all movement (including deliveries) into or out of the farm. Officials may set guidelines for deliveries (e.g. supply drop-offs at farm gate).
- Limit movement of the producer, family members, and employees to essential visits only.
- Establish cleaning and disinfection stations at the entrance to the farm.
- Clean and disinfect all vehicles entering or leaving the premises.
- Control essential service visits (e.g. feed deliveries):
- Visits to the farm under quarantine should be the last stop of the route.
- The driver should not enter animal housing facilities.
- The driver must wear plastic disposable boots.
- The driver must use hand sanitizer before leaving the farm.
- Upon leaving the farm, the vehicle must be thoroughly cleaned and disinfected.
- After leaving the farm, the driver should bathe and launder clothing prior to further stops or discard disposable clothing on site.
- Dispose of dead animals properly, according to rules of local environmental and public health officials and any guidelines established by veterinary officials during the quarantine.
- Dispose of animal products such as milk and eggs on-farm until the farm is released from quarantine.
Personal Protective Equipment (PPE)
Individuals working in an exposed zone around sick animals should wear appropriate personal protective equipment (PPE) to protect themselves and to reduce the risk of carrying the infectious agent off the farm. The US Department of Labor Occupational Safety and Health Administration (OSHA) has established standards for PPE.
Diseases that have the potential to infect humans are extremely hazardous and the highest level of protection should be utilized. Any plan involving a biological hazard should be based on relevant infectious disease or biological safety recommendations by the Centers for Disease Control and Prevention (CDC) and other experts, including emergency first responders, law enforcement, and public health officials. The need for decontamination or medical treatment of exposed farm personnel and first responders should be established after consultation with local public health authorities.
Chemical contaminants and other hazardous materials (e.g., radiological contamination) also pose a risk to the exposed people and emergency responders. The office of Hazardous Material Safety in the US Department of Transportation (DOT) developed the Emergency Response Guidebook (ERG2008) to assist responders in the identification of hazardous materials and to provide guidance on personal safety.
The establishment of decontamination facilities and the provision of personal protective equipment (PPE) are essential in handling all hazardous material incidents. Necessary decontamination equipment includes a safe water and air supply, shelter, decontamination stretchers, decontamination showers, water pump, and water tanks.
There are four levels of PPE (A through D with A being the highest protection level). It is recommended that rescue personnel use at least Level C. All staff members working in PPE should be required to attend training courses including setting up decontamination showers and proper use (don and doff) of PPE. The main focus is to train the staff to protect themselves from different routes of contamination, including skin, respiratory tract and eyes.
More about PPE can be found on the US Environmental Protection Agency, Emergency Response Program - Personal Protective Equipment website.
If PPE is not required for a response, protective clothing may still be needed to prevent personal contamination or injury. The type of protective clothing needed will depend upon the type of agent, concentration, and route of exposure. Disposable coveralls, plastic booties, gloves, and masks are examples of protective clothing. This type of gear will not protect the individual from adverse health effects, but on-site disposal of protective clothing can limit the spread of the agent outside the exposed zone.