has spread with alarming speed across Europe, Africa, and parts of Asia in which the infection was not reported earlier. Establishment of the highly pathogenic avian infl uenza (H5N1) as an endemic virus within duck and poultry populations and its capacity to cross species barriers increase the possibility of adaptation to humans and a pandemic. Human infl uenza infections with subtype H5N1 viruses are often fatal. As of June 4, 2007 , 309 laboratoryconfi rmed cases of human infection have been reported to the World Health Organization (WHO); 61% were fatal, mainly in persons 10-39 years of age (www.who.int/csr/ caculatordisease/avian_infl uenza/en). If a pandemic is triggered by transmissibility of infl uenza (H5N1) from person to person, millions of people could die, and economies would likely be crippled for 6-24 months.