Occupational and consumer risks from avian influenza viruses

Sporadic human infections have been reported with a few select avian influenza (AI) viruses over the past 50 years. Most of the infections resulted from the H7N7 high pathogenicity AI (HPAI) virus from The Netherlands (2003) and H5N1 HPAI viruses from several Asian countries (1997-2005). Epidemiological studies have identified direct exposure to infected poultry as the primary risk factor for human infection. In The Netherlands, veterinarians, cullers and poultry farmers had an occupational risk of infection through exposure to infected commercial poultry, and presented with conjunctivitis and/or influenza-like illnesses. In Asia, most of the clinical infections involved direct exposure to poultry in the smallholder sector or live poultry markets, and not commercial poultry. However, serological data from Hong Kong during 1997 indicated H5N1 infections without clinical disease were associated with occupational exposure. No cases of human AI infection have been linked to consumption of infected or contaminated poultry products. However, HPAI virus can be present in blood, bone and meat of infected poultry, which, if consumed raw, are a potential source of virus for human infections. Cooking and pasteurisation are effective methods of killing AI viruses. Proper vaccination of poultry has been shown to prevent HPAI virus from localising in the meat.