Doctors in Turkey are waiting for the results of tests on four children to find out if they have contracted bird flu. The death of a 14 year old boy has already been confirmed.The children, from the southern city of Van, had all eaten chicken which had been slaughtered while showing signs of the disease. But experts say bird flu is only one possible cause of their illness. One boy and two girls are in hospital. Two other patients, including a child, have had tests. Turkey has had outbreaks of the H5N1 strain in birds, but no human cases so far. Turkey lies on the path of migratory birds, who are believed to spread the virus. There have been two outbreaks of the disease in poultry in the last three months, as well as another in Romania. The six people affected are all from the district of Dogubyazit, a remote, rural area where farming is the main way of life. Poultry transport has been banned and culling will begin shortly, officals say.Millions of birds have been slaughtered across Asia and eastern Europe in an attempt to contain the disease. It is feared the virus could mutate into a form which spreads among humans.