APPLICATION OF BIOLOGICAL AND MOLECULAR TECHNIQUES TO THE DIAGNOSIS AND CONTROL OF AVIAN INFLUENZA AND OTHER EMERGING POULTRY PATHOGENS
Location: Exotic and Emerging Avian Viral Diseases Research Unit
Title: Trade and food safety aspects for avian influenza viruses
Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: May 25, 2007
Publication Date: March 1, 2008
Citation: Swayne, D.E., Thomas, C. 2008. Trade and food safety aspects for avian influenza viruses. In: Swayne, D.E., editor. Avian Influenza. Ames, Iowa: Blackwell Publishing. p. 499-512.
Poultry are the most frequently raised farm animals and, on a global basis, birds are the major source of animal protein in the human diet. Domestic production and distribution systems as well as imported products are critical to meet the culinary demands of consumers as well as supplying markets with other products, such as live birds, hatching eggs, and feathers. The Terrestrial Animal Health Code provides sanitary standards for international trade, and emphasizes science-based risk assessment for safe importation of animals and animal products. The goal is to prevent unacceptable risks to animal and human health while avoiding unjustified or politically motivated trade barriers.
Human endeavors are the most frequent means of spreading notifiable avian influenza (NAI) viruses. This has occurred through movement of infected birds and their products or avian influenza (AI) virus-contaminated equipment and supplies between premises, compartments, regions, and countries. The level of risk in spreading NAI virus through trade is dependent upon several factors including: 1) the presence or absence of NAI in a country, zone, and compartment (CZC) as demonstrated through adequate surveillance and diagnostics, as well as transparent reporting; 2) the type of NAI virus present, such as low pathogenicity (LP) NAI versus high pathogenicity (HP) NAI; 3) the specific type of products traded; and 4) the use of any type of treatments for NAI virus inactivation. Because HPNAI viruses cause systemic infection in poultry, the risk for transfer through trade is greater than for LPNAI viruses. Cross-border transfer of NAI viruses has occurred from both legal and illegal trade of live poultry, other live birds, and avian-derived products. These incidences emphasizes the need for sanitary standards that prevent accidental importation of HPNAI virus that potentially could lead to HPNAI outbreaks. Various mitigation strategies can be used to reduce risk, such as vaccination of poultry in a NAI-affected CZC or using inactivation processes such as cooking or pasteurization of products obtained from an affected CZC.
To date, the total number of confirmed human AI virus infections has been relatively small, with the majority caused by only two lineages: the H5N1 Asian lineage (1996-2007), and the H7N7 Dutch lineage (2003). Because currently circulating HPNAI strains are not easily transmitted to humans, human infection has required exposure to large quantities of virus to the respiratory tract. Most cases have occurred following direct or indirect exposure to infected poultry. Taken together, current data indicate that HPNAI is primarily an animal health issue rather than a human health or food safety issue.