Tuesday Talks with Dr. Patterson

February 3, 2015

Avian Influenza

 Much has been reported over the past couple of weeks about the spreading measles epidemic in California and Arizona, particularly as travelers made plans to attend this year’s Super Bowl in Phoenix.  However, poultry producers, agriculture officials, and public health officials in Canada and the United States have been concerned for the past couple of months about another highly contagious viral infection affecting poultry and wild birds, avian influenza.

 Avian influenza (AI), also called bird flu, is caused by the Type A influenza virus.  This virus can affect poultry, wild bird species, and in some cases mammals.  AI is classified into two broad categories based on the severity of illness caused to poultry: low pathogenic avian influenza (LPAI) and highly pathogenic avian influenza (HPAI).  Poultry infected with LPAI typically show little signs of the illness; poultry infected with HPAI exhibit extreme illness and death occurs at high rates.  Avian influenza is further divided into subtypes based on two proteins found in the virus: hemagglutinin, the “H” protein, and neuraminidase, the “N” protein.  There are 16 H types (H1-H16) and 9 N (N1- N9) types, creating a total of 144 possible combinations.  Wild birds, especially waterfowl are a natural reservoir for the influenza virus.  They are not normally affected by the virus, but can transmit it to more susceptible domesticated birds or poultry.  The H5 and H7 subtypes are of particular concern.  They are common in waterfowl and are typically low pathogenic.  However, they are known to mutate from low pathogenic to high pathogenic after infecting poultry flocks. (CFIA a)

 Concern over avian influenza arose in December when it was discovered in commercial poultry operations in British Columbia.  Agriculture and health officials identified 11 infected premises (farms).  The cases were reported between December 1 and 17 and involved turkeys, broiler breeders, and table egg layers.  The birds were identified to be infected with subtype H5N2 (AP).  To limit the spread of the disease, agriculture officials euthanized the birds and disposed the remains of the infected flocks.  A total of 245,600 birds were affected by this outbreak (CFIA b).  In response to the reported outbreak, eight countries, including the United States, placed restrictions on imports of poultry and poultry products from British Columbia (AP).  U.S. producers and officials were particularly concerned about this outbreak as the infected farms lie in the path of the Pacific flyway used by migratory birds.

 In December and January, avian influenza cases were discovered in Washington, Oregon, and Idaho involving backyard poultry flocks and captive falcons.  These cases, reported between December 4 and January 16, involved HPAI H5N8 and HPAI H5N2 (APHIS).  Following soon after the first reported cases in the United States, China imposed an import ban on all poultry and poultry products from the United States effective January 8 (Enoch).  On January 23, a commercial poultry operation, a turkey ranch in Stanislaus County, California, was affected by HPAI H5N8 (APHIS).  In all of these cases the USDA Animal and Plant Health Inspection Service has worked closely with state agriculture and health officials to quarantine the affected areas, euthanize the birds, and dispose of the remains.  APHIS provides 100 percent compensation to producers for their losses to encourage reporting on outbreaks, so they can be monitored and controlled (APHIS).  Poultry producers are also strongly advised to maintain strict biosecurity protocols to minimize the potential for contact between commercial flocks and infected birds, potentially infected birds (wild birds), or contaminated materials.

 Outbreaks of avian influenza among poultry have been associated with illness and death in humans in Asia, Africa, Europe, the Pacific, and the Near East (CDC).  Transmission to humans occurs when people have had close contact with infected birds or heavily contaminated environments.  Cases of avian influenza illnesses among humans in North America have been rare (CDC).  Furthermore, the number of highly pathogenic avian influenza outbreaks among commercial poultry have been relatively rare in the United States.  Indeed, since 1997, only two cases have been recorded, including the current case in California.  The other case occurred on a chicken farm in Texas in 2004 (CDC).   The greatest risk associated with outbreaks of avian influenza may be the costs associated with the lost economic activity associated with production, processing, and trading poultry and poultry products.  Lost export shipments to China or other markets could be significant.  Through November, the total value of poultry and poultry product shipments to China during 2014 summed to $286 million; in 2013 total calendar year shipments to China summed to $427 million (FAS).

 The United States is fortunate to have suffered such few outbreaks of this virulent disease affecting poultry.  Producers and consumers in the United States are also fortunate to have the best disease monitoring and control systems in the world.  While threats to human health are generally low, the economic losses can be significant.  Continued vigilance in protecting U.S. producers and consumers from this and other possible diseases affecting poultry and livestock is essential.

 References

 Animal and Plant Health Inspection Service.  Update on Avian Influenza Findings in the Pacific Flyway.  U.S. Department of Agriculture.  (Accessed February 3, 2015): http://www.aphis.usda.gov/wps/portal/aphis/ourfocus/animalhealth/sa_animal_disease_information/sa_avian_health/ct_avian_influenza_disease/!ut/p/a1/lVFNc4IwEP0tHnrMJCbIx9GPVlDRTp1W4cKsASRTCAxEp-2vb1DbsQdpm9vuvpfd9x4O8RaHEo5iD0qUEvK2Ds1otnJpf0SoN10798Rbvjz49sJiK9fQgEADyI03JD_5q7lntvwnMnInfbJmeINDHHKpKpXhAKpMNBEvpUqkinKxq6F-vyMNROWhjtKSH5pTBVIUkEdZArnKrjuxaBJokkjItKyLk4jz-ChAfuO5ujQ0LD8k8gO-iO0xFRcxDnbUSYlJE8TsPiCD7xiCAQwQHcRpHHNuMWZdxHeo-8W8k3gNGU-HrmEttGGGTYk30XTL8QnxzAugw99A32DdXOIYeP1PUbM_RE5rf-zv9begMtSajbedIZzHVyHgbUcImxEOzbejM9_jqngubPaOXtPlEoXBozfs9T4B8LuWTg!!/?1dmy&urile=wcm%3apath%3a%2Faphis_content_library%2Fsa_our_focus%2Fsa_animal_health%2Fsa_animal_disease_information%2Fsa_avian_health%2Fct_ai_pacific_flyway

 Associated Press.  “Avian Flu Spreading in Southwest British Columbia.”  The New York Times, December 11, 2014.  (Accessed February 3, 2015): http://www.nytimes.com/aponline/2014/12/11/world/asia/ap-cn-avian-flu.html?_r=0

 Canadian Food Inspection Agency (a).  Fact Sheet – Avian Influenza.  (Accessed February 3, 2015): http://www.inspection.gc.ca/animals/terrestrial-animals/diseases/reportable/ai/fact-sheet/eng/1356193731667/1356193918453

 Canadian Food Inspection Agency (b).  Avian Influenza – British Columbia 2014 Infected Premises.  (Accessed February 3, 2015): http://www.inspection.gc.ca/animals/terrestrial-animals/diseases/reportable/ai/2014-ai-investigation-in-bc/infected-premises/eng/1418340527324/1418340584180

Centers for Disease Control and Prevention.  Outbreaks of Avian Influenza in North America.  (Accessed February 3, 2015): http://www.cdc.gov/flu/avianflu/outbreaks.htm

 Enoch, Daniel.  “AFBF Says China’s Ban on U.S. Poultry Violates Global Trade Rules.”  AgriPulse, January 13, 2015.  (Accessed February 3, 2015): http://www.agri-pulse.com/AFBF-says-China-ban-on-US-poultry-violates-global-trade-rules-01132014.asp

 Foreign Agricultural Service.  Global Agricultural Trade System Online.  U.S. Department of Agriculture.  (Accessed February 3, 2015): http://apps.fas.usda.gov/gats/ExpressQuery1.aspx

 

Dr. Paul Patterson is Associate Dean for Instruction for the College of Agriculture and Professor of Agricultural Economics.