Geneticists monitoring Turkey's bird flu outbreak say the virus has mutated, but the change poses no added threat.
So far the virus has infected 18 people and killed 3 children in the country.
Samples from two Turkish flu victims show that the virus has mutated, but not in a way that would enable human-to-human transmission.
The deadly H5N1 strain of avian influenza has appeared in poultry flocks throughout Turkey.
A 12-year-old girl and her two teenage brothers were the first bird-flu fatalities confirmed outside Southeast Asia. The siblings lived in a rural area in eastern Turkey near the Iranian border.
Turkish authorities have announced aggressive plans to cull some five million birds in an attempt to curb the spread of the disease.
The World Health Organization estimates that the H5N1 virus has infected fewer than 150 people worldwide to date, killing 78.
Experts caution that a bird flu pandemic could kill millions if the virus genetically mutates into a more contagious form.
Sick Birds
Samples from two teenage flu victims in Turkey are being analyzed at the National Institute of Medical Research (NIMR) in London at the request of the World Health Organization.
Two different strains of the virus have been discovered in the teenagers. One carried a viral mutation in a protein called hemagglutinin. Influenza viruses use hemagglutinin to attach to healthy cells.
The mutation has been previously shown to enable the avian flu virus to adhere to and infect cells, including human cells, more easily.
