The third incident in as many weeks of birds succumbing to avian flu has prompted authorities to act fast to prevent a repeat of the 1997 epidemic that killed six people. The incidents occurred in a pond in Kowloon Park, in poultry markets in Kowloon and Lantau Island and in a waterfowl park. The flu is thought to jump from birds to humans because of congested living conditions and poor sanitation at wholesale markets where customers purchase live birds for slaughter. The risk to visitors is low.