Highly pathogenic avian influenza virus A(H7N7) infection of humans and human-to-human transmission during avian influenza outbreak in the Netherlands

During the outbreak of highly pathogenic avian influenza (HPAI) A(H7N7) in the Netherlands in 2003, human infection occurred in unexpectedly high numbers. Initially, all those involved in the culling of poultry were advised to wear protective clothing, goggles, and nose–mouth masks, and to wash their hands after work. In a later stage, vaccination and antiviral prophylaxis of all poultry workers and antiviral treatment of all cases was initiated. Case finding was implemented immediately. Conjunctival and nose/throat swabs were collected from 453 persons. Eighty-nine persons were A(H7) positive, 78 with conjunctivitis only, 5 with conjunctivitis and influenza-like illness (ILI), 2 with ILI only and 4 did not fit the case definitions. Nine A(H7) cases had both positive conjunctival and nose/throat swabs. One A(H7) case had an A(H7) positive nose/throat swab only. Of the two A(H7) cases presenting with ILI only, a veterinarian who developed a respiratory distress syndrome died. Three contacts of two A(H7) positive poultry workers developed A(H7) conjunctivitis. One of these, the 12-year-old daughter of a poultry worker, additionally developed ILI. Since they had no direct exposure to infected poultry, these observations strongly suggest human-to-human transmission. No simultaneous infection with A(H7) and human influenza virus in one patient was detected.