Avian influenza: Effective biosecurity is critical to prevention

By Neogen

Avian influenza (AI) is a very important infectious disease of both poultry and other birds caused by influenza type A viruses. Although multiple viral strains exist, the disease appears in two forms: highly pathogenic avian influenza (HPAI) and low pathogenic avian influenza (LPAI).
white chickens in broiler room

What is avian influenza?

The distinction between pathogenicity of a particular avian influenza virus is based upon its potential to result in severe disease in poultry and the presence of specific genetic attributes that contribute to this virulence. In both poultry and wild birds, LPAI may present either subclinically or as mild respiratory disease. This form of the disease in poultry might be observed as sneezing, coughing, and nasal or ocular discharge with a negative impact on productivity despite mortality remaining low. As a natural reservoir for avian influenza, wild birds in many cases may not exhibit any clinical signs even in the event of HPAI infection. Poultry may experience mortality rates approaching 100 percent during an HPAI outbreak and exhibit clinical signs such as lethargy; severe respiratory distress leading to cyanosis, edema, and hemorrhage in tissues of the head, legs, internal organs, and muscles; neurologic deficits; and diarrhea. Avian influenza viruses have a predilection for the intestinal and respiratory tracts of the bird. Therefore, oropharyngeal and cloacal swabs are common diagnostic samples submitted to detect this pathogen.

How is avian influenza transmitted?

Avian influenza is transmitted through direct contact with infected birds or through direct contact with respiratory secretions or feces from infected birds. As a natural reservoir for avian influenza viruses, wild birds and their migratory patterns pose a significant risk for the transmission of disease to poultry. Contaminated feed, water, litter, equipment, clothing, footwear, and vehicles serve to transmit the virus as well. Birds will contract the virus through inhalation or ingestion upon exposure to a source within their environment.

How is avian influenza treated?

HPAI and specific subtypes of LPAI are on the World Organization for Animal Health (OIE) list of reportable diseases. However, it is the concern for these specific subtypes of LPAI to mutate and development into HPAI that serves as the basis for handling all avian influenza virus detections carefully with appropriate regulatory intervention. There is no effective treatment. Therefore, the confirmation of avian influenza in poultry results in an immediate response involving containment and eradication of the disease. Typical eradication efforts include depopulation, disposal, and decontamination of affected premises. Outbreaks of HPAI in poultry can have a devastating economic impact within the industry as confirmed positive cases impact trade. Furthermore, avian influenza has the potential for zoonosis, therefore, necessary precautions should be considered to protect public health.

How can I prevent my flock from contracting avian influenza?

An effectively implemented, comprehensive biosecurity program is the most important means to prevent transmission of avian influenza and maintain a healthy flock. Recommendations include:

  • Control access to the facility. Access to the production facility should be restricted and a defined secure perimeter established. Limit visitors to essential personnel only that must follow strict protocols for entering and exiting the premise. Maintain a log. Respect appropriate downtimes from previous bird exposure, clean and sanitize hands, disinfect footwear, implement shower in/shower out or Danish entry system with clear lines of separation, and utilize personal protective equipment.
  • Vehicle biosecurity. Implement a program to ensure all vehicles entering and exiting the facility are cleaned and disinfected as well as any equipment. Focus on both internal and external surfaces for the most effective comprehensive approach to preventing exposure to pathogens.
  • Barn biosecurity. Treat each barn on the premise as a separate unit for better control. Clean and sanitize hands, disinfect footwear, and change personal protective equipment between each barn. Clean and disinfect all surfaces between groups of birds. Clean water lines. Implement water treatment.
  • Control wildlife, rodents, and insects. Maintain the site in a manner to limit the activity of wild birds in and around the premise. Implement a pest management control program through the utilization of rodenticides and insecticides to prevent these potential vectors from transmitting disease.
  • Educate and train personnel. It is very important to train personnel on the proper techniques and procedures for implementation of the biosecurity program to ensure consistent high-level execution.

If you suspect avian influenza in a flock:

  • Contact your veterinarian immediately. Your veterinarian will contact the State Veterinarian or a USDA APHIS Veterinary Medical Officer.
  • Do not move any birds from the premise.
  • Prevent any contamination from leaving the facility.
 
Reference: USDA APHIS Veterinary Services

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