Hong Kong authorities say two more dead birds have tested positive for a dangerous strain of bird flu, adding to health worries in the city.
Agriculture officials said Friday that two black-headed gulls found separately about a week ago in rural areas had H5N1 avian influenza. The birds are common visitors in winter.
Last month, a Chinese bus driver who tested positive for H5N1 died in a city bordering Hong Kong. Also, workers in Hong Kong slaughtered nearly 20,000 birds at a market after two dead birds, one a chicken, were found to have the dangerous strain.
H5N1 rarely infects humans and usually only those who come into close contact with diseased poultry. The World Health Organization says globally there have been 336 human deaths from 573 confirmed bird flu cases since 2003.
Explore further: Hong Kong bird tests positive for H5N1