Epidemiological investigations of human cases of avian influenza show that the virus was acquired by direct contact with infected birds [29] [30] [31] [50] [51] [52] [53] [54] [55] [56] . Influenza A is transmitted through the fecal-oral and respiratory routes among wild birds and poultry [32] . Human interaction with these infected secretions and birds was the major mode of transmission, with contact including consumption of undercooked or raw poultry products, handling of sick or dead birds without protection, or food processing at bird cleaning sites. All birds were domesticated (chicken, duck, goose) and no transmission from birds in the wild (migrating) or contaminated waterways has been documented. In a few cases, limited human to human transmission has been reported among health care workers and family members (Table 4 ) [59] [60] [61] [62] [63] . In each of these cases, no personal protective equipment was used, which is the major factor in transmission between humans [60] .