Controlling avian influenza infections: The challenge of the backyard poultry

In recent years the economic damage inflicted by several avian influenza (AI) subtypes (primarily H5N1 and H9N2, but also H7N1, H7N3, H7N7) on the commercial poultry industry and backyard poultry is beyond simple calculation. In response to the continued losses suffered by commercial poultry producers large scale vaccination has been introduced in many affected countries for the commercial sector but in many areas of the world no adequate AI control has been implemented for backyard poultry. In the majority of cases, vaccination has resulted in increased resistance to the field virus challenge, prevented illness, reduced the death rate and limited contamination of the environment (Sims, 2007; Peyre et al, 2009). These measures could ultimately reduce transmission within poultry, reduce the incidence of H5N1, and so reduce the risk of virus spread from birds to humans. Unfortunately, on the grounds of cost, the use of vaccine mainly remains restricted to the commercial poultry operations and few efforts have been made to effectively control avian influenza in backyard poultry. Thus backyard poultry have become a constant reservoir for H5N1 transmission and so pose a threat to the commercial poultry industry and indeed to public health.