Submitted to: Meeting, Center for Food Safety, University of Georgia
Publication Type: Abstract Only
Publication Acceptance Date: 1/10/2005
Publication Date: 3/2/2005
Citation: Swayne, D.E. 2005. Is avian influenza a food safety issue and how do we manage the risk?. [abstract]. Meeting, Center for Food Safety, University of Georgia. p. 14-15.
Technical Abstract: Avian influenza (AI) is a disease of birds caused by a virus and was first described in Northern Italy in 1878. This original report was of highly pathogenic (HP) AI or fowl plague, which is a severe, systemic disease causing high death losses. In the mid-1950's, low pathogenic (LP) AI was reported which caused localized diseases including respiratory and drops in egg production. Typically, AI viruses have infected only various species of birds, including poultry, and rarely infected mammals. Beginning in 1996, an H5N1 HPAI virus emerged in Asia and since December 2003 over 200 million poultry have been infected or culled because of the virus. In addition, at least 44 human have been infected and hospitalized in Thailand and Vietnam. Of the hospitalized, 32 have died. The method of exposure has been direct contact with infected poultry, primarily to village chickens or fighting cocks. In the USA, LPAI is very rare in poultry and HPAI has only been reported twice in the last 50 years (1983-84 and 2004). The USA does not have the H5N1 HPAI virus that is infecting poultry in Asia. Recent experimental studies have demonstrated some important findings: ' LPAI viruses produce local infection in respiratory and digestive tracts of chickens with virus being present in nasal cavity, trachea, lungs, air sacs, intestines, respiratory secretions and feces. However, the LPA viruses do not spread systemically through the blood nor do they infect meat or bone. ' HPAI viruses produce a systemic infection in chickens, and virus can be found in the blood, meat and bone ' Feeding of meat from LPAI virus infected chickens to naive chickens did not transmit the LPAI virus to naive chickens, but feeding meat from HPAI virus infected chickens did transmit the HPAI virus. ' Pasteurization processes used by the egg industry will inactivate any AI viruses that might be present in yolk or albumin. However, AI virus has only be identified in eggs laid by chickens infected with HPAI viruses and not in chickens infected by LPAI viruses. ' Cooking of meat to 70 C will inactivate AI viruses Epidemiological studies in Hong Kong during 1997-98 indicated that the risk to humans for acquiring the H5N1 HPAI was assocated with direct contact with infected chickens and not handling raw meat, cooking or consuming poultry meat. This suggests that human risk is greatest for people with exposure to infected poultry, i.e. respiratory secretions and feces, and risk through meat is much lower. The greatest at-risk human population for avian influenza infections would be poultry farmers, veterinarians and processing plant workers who have contact with infected flocks. HPAI infected flocks should not be processed for food and LPAI-infected flocks should only be processed after recovery from the infection.