Influenza
The main historical features of avian influenza (AI) include: initial high pathogenicity avian influenza (HPAI) cases reported in Northern Italy and clinical differentiation of HPAI from fowl cholera in 1880 and etiology demonstrated as a filterable agent in 1901. Economic losses from AI have varied depending on the strain of virus, species of bird infected, number of farms involved, control methods used, and the speed of implementation of control or eradication strategies. HPAI and H5/H7 low pathogenicity AI are of interest to the World Organization for Animal Health. Based on morphologic and biochemical evidence, AI viruses exert pathological effect on avian cells by two mechanisms: necrosis or apoptosis. Because of the broad spectrum of signs and lesions reported with infections by AI viruses in several species, a definitive diagnosis must be made by virologic and serologic methods. Interventions for AI include measures designed to: prevent introduction of virus and eliminate/eradicate the virus.