Turkey is reporting two more human cases of bird flu, in the same town where three siblings have died. A World Health Organization spokeswoman tells VOA there is no sign of human-to-human transmission of the deadly H5N1 strain of the virus.

An Agriculture Ministery employee throws a sack, full of dead or alive poultry, into a hole at a dump where all poultry was to destroyed in the eastern Turkish town of Dogubayazit, near the Iranian border

A World Health Organization spokeswoman, Maria Cheng, says the spread of bird flu from East Asia to another part of the world is of concern. But, she tells VOA there is no sign of human-to-human transmission, which health experts fear could set off a human pandemic.

"There is nothing to date that shows us that the virus has become more transmissible among humans. We have not seen any changes in the patterns in which it is being transmitted yet. At the same time, we are still at a very preliminary stage, and we do not have a lot of information. So, it is something that we are taking very seriously, and we are investigating to get information as soon as possible," she said.

The WHO says the two teenagers who died were infected with the deadly H5N1 strain of avian flu. The world health body says they had been in close contact with poultry infected with the virus. Samples from a third sibling, an 11 year-old girl who died of suspected bird flu, have been sent to a laboratory in Britain for testing to see if she also carried the H5N1 strain.

The Turkish Ministry of Health reports that two other children aged five and eight have fallen ill in the same region. The ministry says it suspects they too may have bird flu. But, this is yet to be confirmed.

Ms. Cheng says WHO specialists currently in the Turkish capital, Ankara, hope to go to the affected province, where the cases of bird flu were identified. "They will be helping authorities there to conduct a comprehensive epidemiological investigation. So, they will look at how these (human) cases might have been infected, to identify risk behaviors, and also to strengthen infection control, and improve treatment of people who are suspected of being infected with H5," she said.

Until now, 142 human cases of H5N1 infections, including 74 deaths, have been reported in Vietnam, Thailand, Cambodia, Indonesia and China. It is believed that poultry in Turkey was infected by wild birds that migrated to the region last year.