The latest outbreak of bird flu in Cambodia which has seen the hospitalisation of three more suspected cases is causing concern.
The cases follow the death of a three year old child from the deadly virus in a neighboring village in Kompong Speu province, about 45 kilometers west of the capital.
Officials think the toddler became infected after playing with sick chickens.
The two adults and a child are being treated for fever and respiratory problems at a hospital in the capital Phnom Penh.
The World Health Organization (WHO) is reportedly very concerned as the death is the first this year in Cambodia and the fifth since 2003.
Cambodia's department of infectious diseases says five others who had contact with the three suspected cases are also being treated; it is not known how the infection was contracted.
Tests on poultry in the area have found no trace of H5N1 despite the deaths of hundreds in the area earlier this month.
The WHO is particularly concerned as if the three people are found to have bird flu it would signify an exposure to birds that health authorities are unaware of.
Other villagers thought to have caught bird flu after the girl died have tested negative for the virus.
Cambodia's last outbreak of bird flu in humans occurred in early 2005, but the virus has been found in ducks in eastern Kompong Cham province twice since February, and has prompted the slaughter of hundreds of birds.
The Chinese Ministry of Health has confirmed that a 29-year-old woman in Shanghai died from bird flu, and Indonesian authorities are waiting for confirmation that the death of a one year old girl in Jakarta was from the virus.
If tests confirm the girl died from bird flu it would take Indonesia's human deaths from bird flu to 23.
This first case in Shanghai brings China's death toll from bird flu to 11 according to the World Health Organization.
The death of the migrant worker from the virus was confirmed by China's national Center for Disease Control, but as yet it is unclear how she contracted the virus.
There have been no reported bird flu outbreaks in poultry in Shanghai since 2004.